Cefdinir

What it is

Cefdinir is a semisynthetic cephalosporin antibiotic taken by mouth, as 300 mg capsules or as a powder made up into a suspension for children. Chemically it is a beta-lactam; it is a white to slightly brownish-yellow solid. Only about a fifth of an oral dose is absorbed - the label gives 21% bioavailability for a 300 mg capsule and 16% for 600 mg. It is active against common respiratory bacteria such as Streptococcus pyogenes, penicillin-susceptible pneumococcus, Haemophilus influenzae and Moraxella catarrhalis, and inactive against Pseudomonas, Enterobacter, enterococci and MRSA.

What the research says

Cefdinir kills bacteria by blocking cell wall construction. The more interesting question is how much that helps, and the answer depends heavily on which infection. For the conditions cefdinir is approved for, the placebo-controlled evidence for antibiotics as a class is modest: in children with acute ear infection antibiotics do not reduce pain at 24 hours and cause an extra adverse event for every 14 children treated; in acute sinusitis about 80% of people improve within two weeks without them; in sore throat 82% of untreated people are symptom-free within a week. Cefdinir's own trials were mostly non-inferiority comparisons against other antibiotics rather than against placebo, and in acute otitis media it came out somewhat behind high-dose amoxicillin-clavulanate.

Evidence grade: Limited evidence.

How it works

Drug class: Third-generation (extended-spectrum) semisynthetic oral cephalosporin antibacterial

Cefdinir is a beta-lactam. It kills bacteria by stopping them building their cell wall, so the wall fails and the cell dies. It resists destruction by some, but not all, bacterial beta-lactamase enzymes, which is why it still works against some organisms that have become resistant to penicillins. (Source 1)

What it is used for

• The Cochrane review of antibiotics versus placebo in 13 trials and 3,401 children found no reduction in pain at 24 hours (RR 0.89) and about a third fewer children in pain at two to three days (NNTB 20), at the cost of one extra adverse event for every 14 treated. Against high-dose amoxicillin-clavulanate, cefdinir matched on intention-to-treat cure (82% vs 85%) but was behind per-protocol (82% vs 90%, p = 0.045). Evidence: limited. (Source 2)
• The Cochrane review of 29 trials and 15,337 cases found antibiotics reduce sore throat at day three (RR 0.70, NNTB under six) but that 82% of untreated people were symptom-free by one week, and harms were too poorly reported to quantify. Cefdinir's own trials were against penicillin, where it eradicated Streptococcus pyogenes more often; an umbrella review found sufficient evidence for short-course cephalosporin in pharyngotonsillitis. Evidence: limited. (Source 3)
• The Cochrane review of nine placebo-controlled studies in 1,915 participants found antibiotics reduced clinical failure (RR 0.66, 95% CI 0.47 to 0.94) but that cure or improvement was 86% on placebo versus 91% on antibiotic, and about 80% of those treated without antibiotics improved within two weeks. Adverse effects were more common on antibiotics by a median of 10.5%. Evidence: limited. (Source 4)
• The label's own pivotal trials were active comparisons: cefdinir was equivalent to cefaclor in a US pneumonia study and not equivalent to amoxicillin-clavulanate on overall clinical cure in a European one. An umbrella review of 30 systematic reviews, generally of low to critically low quality, supports a five-day duration for non-ICU community-acquired pneumonia and COPD exacerbation in people who have improved clinically. Evidence: limited. (Source 5)
• We did not reach any systematic review or placebo-controlled trial of cefdinir for skin infections. The label indicates it for mild to moderate infections caused by susceptible strains and notes cefdinir is inactive against methicillin-resistant staphylococci, which matters because those are a common cause of skin infection. Evidence: unknown. (Source 5)

Interactions

• Iron supplements, iron-containing multivitamins and iron-fortified infant formula (pharmacokinetic study): Iron binds cefdinir in the gut so much less of the antibiotic is absorbed - absorption fell by 80% with a 60 mg elemental iron supplement and by 31% with a vitamin containing 10 mg. The complex also turns the stool red. (Source 6)
• Iron-fortified breakfast cereals and other heavily iron-fortified foods (theoretical): The same binding is plausible with iron-fortified food, but it has not actually been measured, so the size of the effect is unknown. (Source 6)
• Antacids containing magnesium or aluminium (for example Maalox) (pharmacokinetic study): Taken together, the antacid cuts both the speed and the amount of cefdinir absorbed by roughly 40% and delays the peak by an hour. Separating the two by two hours removed the effect in the study. (Source 7)
• Probenecid (pharmacokinetic study): Probenecid blocks the kidney's excretion of cefdinir, roughly doubling total drug exposure and raising peak levels by 54%. (Source 8)
• Urine glucose tests and the direct Coombs test (label): Not a drug interaction but a laboratory one: cefdinir can make copper-reduction urine glucose tests read falsely positive, and cephalosporins can occasionally turn a direct Coombs test positive. (Source 9)
• A high-fat meal (pharmacokinetic study): Food lowers the peak level by 16% and total exposure by 10%, which the label judges unlikely to matter clinically; cefdinir can be taken with or without food. (Source 10)

Stopping it

• There is no dependence or withdrawal syndrome with cefdinir. The question with antibiotics is course length. The label's position is that stopping early can reduce the treatment's effect and promote resistance. (Source 11)
• The literature on duration is thinner than the practice suggests: an umbrella review of 30 systematic reviews rated them generally of low to critically low quality, while still finding sufficient evidence for a five-day course in non-ICU community-acquired pneumonia and COPD exacerbation in people who have improved clinically. (Source 12)
• For throat infection specifically, the same umbrella review found sufficient evidence to support a short course of a cephalosporin, which is the class cefdinir belongs to. (Source 12)
• Diarrhoea that begins after an antibiotic course may not be a simple side effect: the label notes Clostridium difficile associated diarrhoea has been reported more than two months after the last dose. (Source 13)

What goes wrong

Antibiotics for ear infection in children caused one extra case of vomiting, diarrhoea or rash for every 14 children treated. (Source 2)

• Systematic review, High certainty.
• Size: 8 trials, 2,107 children.
• Who: Children with acute otitis media.
• How long: duration of treatment and immediate follow-up.
• Result: RR 1.38, 95% CI 1.16 to 1.63, NNTH 14 against placebo.
• Funding: Cochrane review; funding not stated in abstract.

Antibiotics increase the risk of adverse events such as vomiting, diarrhoea or rash (RR 1.38, 95% CI 1.16 to 1.63; number needed to treat for an additional harmful outcome (NNTH) 14; 8 trials, 2107 children; high-certainty evidence).

Diarrhoea on cefdinir was about twice as common as on placebo in children treated for acute otitis media. (Source 14)

• Meta-analysis, Low certainty.
• Size: 82 studies pooled.
• Who: Children treated for acute otitis media.
• How long: duration of antibiotic courses.
• Result: Incidence of diarrhoea: azithromycin 2.2%, placebo 6.9%, low-dose amoxicillin 8.7%, cefdinir 13.0%, high-dose amoxicillin 13.8%, high-dose amoxicillin/clavulanate 18.9%.
• Funding: not stated.

Limit of this finding: The review's own conclusion is that the rate of adverse events varies widely depending on which antibiotic is used and on how the information was collected or reported. The percentages for different drugs come from studies that recorded side effects in different ways, so they are not strictly comparable with one another.

The incidence of diarrhea, listed from lowest to highest, was azithromycin (2.2%), placebo (6.9%), low-dose amoxicillin (8.7%), cefdinir (13.0%), high-dose amoxicillin (13.8%), and high-dose amoxicillin/clavulanate (18.9%).

Third- and fourth-generation cephalosporins are among the antibiotic classes most strongly associated with healthcare facility-associated Clostridioides difficile infection. (Source 15)

• Systematic review, Low certainty.
• Size: Studies published from 1 January 2013 to 31 December 2020, pooled by random-effects meta-analysis (number of studies not stated in the abstract)
• Who: Adult hospital inpatients, predominantly in North America or Europe.
• How long: exposure windows before C. difficile onset.
• Result: Cases more than twice as likely to have had recent exposure to these antibiotics; effect sizes variable with heterogeneity across most classes.
• Funding: not stated.

Carbapenems and third- and fourth-generation cephalosporin antibiotics remain the most strongly associated with HCFA-CDI, with cases more than twice as likely to have recent exposure to these antibiotics prior to developing HCFA-CDI.

In people with a proven penicillin allergy, the risk of cross-reaction to a cephalosporin depends on side-chain similarity rather than on generation, and is low for cephalosporins unlike penicillins. (Source 16)

• Meta-analysis, Low certainty.
• Size: 21 observational studies, 1,269 penicillin-allergic patients.
• Who: Patients with IgE- or T-cell-mediated penicillin allergy confirmed by skin test or drug provocation test.
• How long: not applicable.
• Result: 16.45% (95% CI 11.07-23.75) for aminocephalosporins sharing an identical side chain; 5.60% (95% CI 3.46-8.95) for intermediate similarity; 2.11% (95% CI 0.98-4.46) for low similarity scores.
• Funding: not stated.

Limit of this finding: The authors state in their conclusions that it remains possible these meta-analyses overestimated the risk of cross-reactivity, so 16.45% for aminocephalosporins is an upper-end figure. The review also reports a much lower risk for carbapenems, 0.87%, which is reported separately in this write-up.

Twenty-one observational studies on cephalosporin cross-reactivity involving 1269 penicillin-allergic patients showed that the risk of cross-reactivity varied with the degree of similarity between R1 side chains: 16.45% (95% CI, 11.07-23.75) for aminocephalosporins, which share an identical side chain with a penicillin (similarity score = 1), 5.60% (95% CI, 3.46-8.95) for a few cephalosporins with an intermediate similarity score (range, 0.563-0.714), and 2.11% (95% CI, 0.98-4.46) for all those with low similarity scores (below 0.4), irrespective of cephalosporin generation.

Cefdinir taken with iron forms a complex that turns the stool red, which has repeatedly been mistaken for gastrointestinal bleeding. (Source 17)

• Case report, Very low certainty.
• Size: One 9-month-old infant, with a positive rechallenge.
• Who: Breastfed infant also receiving iron-containing infant formula during a 10-day cefdinir course.
• How long: two separate courses.
• Result: Red stools appeared on day 5 of the first course and 48 hours into the second, were guaiac negative, and resolved within 48 hours and within hours of stopping respectively; causality judged highly probable on the Naranjo scale.
• Funding: not stated.

Three weeks later, he again received cefdinir for recurrent otitis media. Red stools reappeared 48 hours later, were determined to be guaiac negative, and resolved within hours of drug discontinuation.

The label records that 3% of 5,093 adults and adolescents in the cefdinir trials stopped the drug for adverse events, mostly gastrointestinal - a manufacturer's position dated 2025. (Source 18)

• Official position, Certainty not rated.
• Size: 5,093 adult and adolescent patients (3,841 US, 1,252 non-US)
• Who: Patients given 600 mg/day cefdinir capsules in the registration programme.
• How long: course lengths of 5 to 10 days.
• Result: 147/5,093 (3%) discontinued for adverse events; 19/5,093 (0.4%) discontinued for rash; label table gives diarrhoea 15% and nausea 3% in US trials.
• Funding: manufacturer label.

One hundred forty-seven of 5093 (3%) patients discontinued medication due to adverse events thought by the investigators to be possibly, probably, or definitely associated with cefdinir therapy. The discontinuations were primarily for gastrointestinal disturbances, usually diarrhea or nausea.

Cefdinir can cause Clostridium difficile associated diarrhoea ranging from mild to fatal colitis, and it can begin more than two months after the course - a label position dated 2025. (Source 13)

• Official position, Certainty not rated.
• Size: not stated.
• Who: Patients given cefdinir or nearly any antibacterial agent.
• How long: up to two months or more after administration.
• Result: No rate given on the label; the mechanism stated is that antibacterials alter normal colonic flora, letting C. difficile overgrow.
• Funding: manufacturer label.

Clostridium difficile associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including cefdinir, and may range in severity from mild diarrhea to fatal colitis.

Serious reactions including anaphylaxis with rare fatalities, Stevens-Johnson syndrome, toxic epidermal necrolysis, fulminant hepatitis and hepatic failure have been reported since 1991 - a label position dated 2025, without rates. (Source 19)

• Official position, Certainty not rated.
• Size: not stated (spontaneous postmarketing reports since approval in Japan in 1991)
• Who: Patients given cefdinir worldwide.
• How long: not applicable.
• Result: No rates are given; the label lists the events regardless of their relationship to cefdinir.
• Funding: manufacturer label.

beginning with approval in Japan in 1991: shock, anaphylaxis with rare cases of fatality, facial and laryngeal edema, feeling of suffocation, serum sickness-like reactions, conjunctivitis, stomatitis, Stevens-Johnson syndrome, toxic epidermal necrolysis, exfoliative dermatitis, erythema multiforme, erythema nodosum, acute hepatitis, cholestasis, fulminant hepatitis, hepatic failure, jaundice

Giving antibiotics immediately rather than watching and waiting increased vomiting, diarrhoea or rash, with one extra child affected for every ten treated. (Source 20)

• Systematic review, High certainty.
• Size: 3 trials, 946 children, within six trials of 1,556 children.
• Who: Children with acute otitis media in high-income countries.
• How long: Course of treatment.
• Result: RR 1.87, 95% CI 1.39 to 2.51; number needed to treat for an additional harmful outcome 10; high-certainty evidence.
• Funding: independent.

Immediate antibiotics increase the risk of vomiting, diarrhoea or rash (RR 1.87, 95% CI 1.39 to 2.51; NNTH 10; 3 trials, 946 children; high-certainty evidence).

What the evidence supports

In children with acute otitis media, antibiotics reduced the number still in pain at two to three days and slightly reduced tympanic membrane perforations. (Source 2)

• Systematic review, High certainty.
• Size: 13 trials, 3,401 children and 3,938 acute otitis media episodes.
• Who: Children with acute otitis media in high-income countries.
• How long: outcomes to 24 hours, 2-3 days, 4-7 days, 10-14 days and up to 3 months.
• Result: Pain at 2-3 days RR 0.71, 95% CI 0.58 to 0.88, NNTB 20; tympanic membrane perforation RR 0.43, 95% CI 0.21 to 0.89, NNTB 33.
• Funding: Cochrane review; funding not stated in abstract.

but result in almost a third fewer children having pain at two to three days (RR 0.71, 95% CI 0.58 to 0.88; number needed to treat for an additional beneficial outcome (NNTB) 20; 7 trials, 2320 children; high-certainty evidence)

Antibiotics reduced sore throat symptoms at day three, though most people in the placebo groups were better within a week anyway. (Source 3)

• Systematic review, Moderate certainty.
• Size: 29 trials, 15,337 cases of sore throat.
• Who: Children and adults presenting to medical care with sore throat; most participants were adults.
• How long: outcomes at day three, one week, 14 days and two months.
• Result: Sore throat at day three RR 0.70, 95% CI 0.60 to 0.80; NNTB under six at day three and 18 at one week.
• Funding: Cochrane review; funding not stated in abstract.

The reduction in sore throat symptoms at day three (risk ratio (RR) 0.70, 95% confidence interval (CI) 0.60 to 0.80; 16 studies, 3730 participants; moderate-certainty evidence) was greater than at one week in absolute numbers (RR 0.50, 95% CI 0.34 to 0.75; 14 studies, 3083 participants; moderate-certainty evidence) due to many cases in both treatment groups having resolved by this time.

Antibiotics reduced clinical failure in acute maxillary sinusitis, but the absolute gain was small. (Source 4)

• Systematic review, Moderate certainty.
• Size: Nine placebo-controlled studies, 1,915 participants; five low-risk-of-bias studies with 1,084 randomised in the main analysis.
• Who: Immunocompetent adults in primary care with acute maxillary sinusitis and symptoms lasting at least seven days.
• How long: 7 to 15 days and 16 to 60 days follow-up.
• Result: Clinical failure pooled RR 0.66, 95% CI 0.47 to 0.94; cure or improvement 86% placebo versus 91% antibiotic.
• Funding: Cochrane review; funding not stated in abstract.

In these studies antibiotics decreased the risk of clinical failure (pooled RR of 0.66, 95% CI 0.47 to 0.94, 1084 participants randomised, 1058 evaluated, moderate quality evidence).

Cefdinir matched high-dose amoxicillin-clavulanate on intention-to-treat cure in young children with acute otitis media. (Source 21)

• Randomized trial, Low certainty.
• Size: 318 children aged 6 months through 6 years.
• Who: Young children with non-refractory acute otitis media.
• How long: 10 days of treatment, assessment on day 12-15.
• Result: Intention-to-treat clinical cure 82% (129/158) cefdinir versus 85% (134/158) amoxicillin-clavulanate, p = 0.547, 95% CI -11.7 to 5.4.
• Funding: not stated; investigator-blinded multicentre comparison of a branded product.

Limit of this finding: Two things to know about this trial. Its per-protocol comparison prints p = 0.045, below the usual 0.05 threshold, alongside a 95% confidence interval of -16.4 to 0.0 whose upper limit is exactly no difference; one of the two has been rounded, so treat it as borderline rather than clear-cut. And the trial was investigator-blinded rather than double-blind, so the parent-reported figures for taste, ease of use and adherence came from parents who knew which suspension their child had been given.

At the EOT visit, for cefdinir and amoxicillin/clavulanate, respectively, intent-to-treat (ITT) clinical cure rates were 82% (129/158) and 85% (134/158) (p = 0.547; 95% confidence interval [CI] -11.7 to 5.4) and per-protocol cure rates were 82% (123/150) and 90% (129/143) (p = 0.045; 95% CI -16.4 to 0.0).

Antibiotics reduced two suppurative complications of sore throat, acute otitis media within 14 days and quinsy within two months. (Source 22)

• Systematic review, High certainty.
• Size: 10 studies, 3,646 participants for otitis media; 8 studies, 2,433 participants for quinsy.
• Who: Children and adults presenting with sore throat; most trials conducted in the 1950s.
• How long: 14 days and two months.
• Result: Acute otitis media within 14 days Peto OR 0.21, 95% CI 0.11 to 0.40; quinsy within two months Peto OR 0.16, 95% CI 0.07 to 0.35; both high-certainty evidence.
• Funding: independent.

Limit of this finding: These complication figures come mostly from trials run in the 1950s, when the complications in question were far commoner than they are today, so the absolute benefit in current practice is smaller than these ratios suggest.

antibiotics reduced the incidence of acute otitis media within 14 days (Peto odds ratio (OR) 0.21, 95% CI 0.11 to 0.40; 10 studies, 3646 participants; high-certainty evidence) and quinsy within two months (Peto OR 0.16, 95% CI 0.07 to 0.35; 8 studies, 2433 participants; high-certainty evidence)

What the evidence does not support

Antibiotics did not reduce ear pain at 24 hours in children with acute otitis media. (Source 2)

• Systematic review, High certainty.
• Size: 5 trials, 1,394 children for the 24-hour outcome.
• Who: Children with acute otitis media in high-income countries.
• How long: 24 hours.
• Result: RR 0.89, 95% CI 0.78 to 1.01 (high-certainty evidence); no reduction at four to seven days either (RR 0.76, 95% CI 0.50 to 1.14)
• Funding: Cochrane review; funding not stated in abstract.

Antibiotics do not reduce pain at 24 hours (risk ratio (RR) 0.89, 95% confidence interval (CI) 0.78 to 1.01; 5 trials, 1394 children; high-certainty evidence)

On per-protocol analysis cefdinir cured fewer children with acute otitis media than high-dose amoxicillin-clavulanate, with the shortfall concentrated in recurrent cases and children under two. (Source 21)

• Randomized trial, Low certainty.
• Size: 318 randomised; 150 and 143 in the per-protocol groups.
• Who: Children 6 months through 6 years with non-refractory acute otitis media.
• How long: 10 days.
• Result: Per-protocol cure 82% (123/150) cefdinir versus 90% (129/143) amoxicillin-clavulanate, p = 0.045, 95% CI -16.4 to 0.0; reduced cefdinir response in recurrent acute otitis media (p = 0.010) and under 24 months (p = 0.039)
• Funding: not stated.

Limit of this finding: Two things to know about this trial. Its per-protocol comparison prints p = 0.045, below the usual 0.05 threshold, alongside a 95% confidence interval of -16.4 to 0.0 whose upper limit is exactly no difference; one of the two has been rounded, so treat it as borderline rather than clear-cut. And the trial was investigator-blinded rather than double-blind, so the parent-reported figures for taste, ease of use and adherence came from parents who knew which suspension their child had been given.

This difference was driven primarily by reduced cefdinir response in patients with recurrent AOM (p = 0.010) and those younger than 24 months (p = 0.039).

A systematic review of 12 randomised trials found amoxicillin-clavulanate better than cefdinir at clearing Streptococcus pneumoniae from culture. (Source 23)

• Systematic review, Very low certainty.
• Size: 12 randomised controlled trials, two of them of cefdinir.
• Who: Children 6 months to 12 years with acute otitis media.
• How long: not stated in the abstract.
• Result: No pooled estimate: the reviewers did not evaluate the meta-analysis because of substantial heterogeneity between studies.
• Funding: not stated.

Limit of this finding: The review's recommendation runs ahead of its own results. It says amoxicillin-clavulanate should be the treatment of choice, while reporting that in seven of its twelve trials (58.3%) the drug was only comparable with other antibiotics or with placebo, that relapse rates were comparable, and that no pooled analysis could be done at all because the trials differed too much. Read it as one review's opinion rather than as a pooled result.

However, amoxicillin-clavulanate was more effective in eradicating Streptococcus pneumoniae from the culture, when compared to cefdinir.

Most people with acute sinusitis get better within two weeks without any antibiotic. (Source 24)

• Systematic review, Moderate certainty.
• Size: Nine placebo-controlled studies, 1,915 participants.
• Who: Immunocompetent primary care patients with uncomplicated acute sinusitis.
• How long: two weeks.
• Result: About 80% of participants treated without antibiotics improved within two weeks.
• Funding: Cochrane review; funding not stated in abstract.

Limit of this finding: This review prints two different figures for how many people recover without antibiotics: about 80% within two weeks in its conclusions, and 86% cured or improved at 7 to 15 days in its results. They come from different outcome definitions in the same paper, so they are not a correction of one another; either way, the large majority recover untreated.

However, about 80% of participants treated without antibiotics improved within two weeks.

Most sore throats settle without antibiotics, and antibiotics did not reduce fever at day three. (Source 3)

• Systematic review, Moderate certainty.
• Size: 29 trials, 15,337 cases.
• Who: Children and adults seeking care for sore throat.
• How long: to two months for complications.
• Result: 82% of the placebo or no-treatment group were symptom-free by one week; fever at day three not reduced (RR 0.75, 95% CI 0.53 to 1.07)
• Funding: Cochrane review; funding not stated in abstract.

Compared with placebo or no treatment, antibiotics did not significantly reduce fever at day three (RR 0.75, 95% CI 0.53 to 1.07; 8 studies, 1443 participants; high-certainty evidence)

The tympanometry benefit of antibiotics in children's ear infection had gone by six to eight weeks, and antibiotics did not reduce later ear-infection recurrences or serious complications. (Source 20)

• Systematic review, Certainty not rated.
• Size: Up to 6 trials and 2,200 children per outcome, within 13 placebo-controlled trials of 3,401 children.
• Who: Children with acute otitis media in high-income countries.
• How long: Six to eight weeks, three months, and late recurrence.
• Result: Abnormal tympanometry at six to eight weeks RR 0.89, 95% CI 0.70 to 1.13; at three months RR 0.94, 95% CI 0.66 to 1.34; late AOM recurrences RR 0.94, 95% CI 0.79 to 1.11.
• Funding: independent.

However, antibiotics do not reduce the risk of abnormal tympanometry findings at six to eight weeks (RR 0.89, 95% CI 0.70 to 1.13; 3 trials, 953 children) and at three months (RR 0.94, 95% CI 0.66 to 1.34; 3 trials, 809 children) or late AOM recurrences (RR 0.94, 95% CI 0.79 to 1.11; 6 trials, 2200 children).

The same review found cross-reactivity to carbapenems in penicillin-allergic patients to be very low, under one per cent. (Source 16)

• Meta-analysis, Low certainty.
• Size: 11 observational studies, 1,127 penicillin-allergic patients.
• Who: Patients with penicillin allergy confirmed by skin test or drug provocation test.
• How long: Not applicable.
• Result: Risk of cross-reactivity to any carbapenem 0.87% (95% CI, 0.32-2.32)
• Funding: not stated.

Limit of this finding: The authors say in their own conclusions that these meta-analyses may have overestimated the risk of cross-reactivity, so all the percentages in this review, including the 16.45% for aminocephalosporins, are best read as upper-end estimates.

Eleven observational studies on carbapenem cross-reactivity involving 1127 penicillin-allergic patients showed that the risk of cross-reactivity to any carbapenem was 0.87% (95% CI, 0.32-2.32).

Antibiotics did not reduce acute sinusitis after sore throat, and there were too few cases of acute glomerulonephritis to tell whether they protect against it. (Source 22)

• Systematic review, Low certainty.
• Size: 8 studies, 2,387 participants for sinusitis; 10 studies, 5,147 participants for glomerulonephritis.
• Who: Children and adults presenting with sore throat.
• How long: 14 days.
• Result: Acute sinusitis within 14 days Peto OR 0.46, 95% CI 0.10 to 2.05 (high-certainty evidence); acute glomerulonephritis Peto OR 0.07, 95% CI 0.00 to 1.32 (low-certainty evidence)
• Funding: independent.

but not acute sinusitis within 14 days (Peto OR 0.46, 95% CI 0.10 to 2.05; 8 studies, 2387 participants; high-certainty evidence).

The sore throat review could not quantify the harms of antibiotics at all, because the trials reported them poorly, and most of those trials date from the 1950s. (Source 25)

• Systematic review, Certainty not rated.
• Size: 29 trials, 15,337 cases of sore throat.
• Who: Children and adults presenting with sore throat, ranging from under one year to over 50.
• How long: Varied.
• Result: Harms not quantified; the review reports that harms were poorly or inconsistently reported across the included trials.
• Funding: independent.

Harms from antibiotics were poorly or inconsistently reported, and were thus not quantified for this review.

Where the research disagrees

Whether cefdinir is an acceptable first choice for acute otitis media in children

• Authors of the 2023 systematic review of antimicrobials versus amoxicillin-clavulanate, systematic review of 12 randomised trials; meta-analysis not evaluated because of heterogeneity: In five (41.7%) RCTs, amoxicillin-clavulanate proved to be superior to azithromycin, cefdinir, placebo, cefaclor and penicillin V, while in seven (58.3%) RCTs its efficacy was comparable with other antimicrobials or placebo. (Source 23)
• Investigators of the 2000 randomised comparison in suppurative acute otitis media, investigator-blinded randomised multicentre trial, 752 patients entered, 595 evaluable: Response rates in the three treatment groups were similar. (Source 26)

Whether 'up to 10%' is the right figure for cephalosporin cross-reactivity in penicillin allergy

• FDA-approved cefdinir label (position, 2025), regulatory label text, no study cited: IF CEFDINIR IS TO BE GIVEN TO PENICILLIN-SENSITIVE PATIENTS, CAUTION SHOULD BE EXERCISED BECAUSE CROSS-HYPERSENSITIVITY AMONG β-LACTAM ANTIBIOTICS HAS BEEN CLEARLY DOCUMENTED AND MAY OCCUR IN UP TO 10% OF PATIENTS WITH A HISTORY OF PENICILLIN ALLERGY. (Source 27)
• Picard and colleagues, two systematic reviews and meta-analyses (2019), meta-analysis of 21 observational studies in 1,269 patients with confirmed penicillin allergy: Twenty-one observational studies on cephalosporin cross-reactivity involving 1269 penicillin-allergic patients showed that the risk of cross-reactivity varied with the degree of similarity between R1 side chains: 16.45% (95% CI, 11.07-23.75) for aminocephalosporins, which share an identical side chain with a penicillin (similarity score = 1), 5.60% (95% CI, 3.46-8.95) for a few cephalosporins with an intermediate similarity score (range, 0.563-0.714), and 2.11% (95% CI, 0.98-4.46) for all those with low similarity scores (below 0.4), irrespective of cephalosporin generation. (Source 16)

How much

• Reference intake: Dosing is set by the prescriber, not by the reader. As a position, the 2025 label states the total daily dose for all infections in adults and adolescents is 600 mg, and that once-daily dosing for 10 days is as effective as twice-daily dosing except in pneumonia and skin infections, where it has not been studied. (Source 28)
• Upper limit: As a position, the 2025 label's maximum is 600 mg per day for adults and adolescents; there is no higher approved dose, and the label states plasma increases are less than dose-proportional from 300 mg to 600 mg so bioavailability falls from 21% to 16% as the dose doubles. (Source 10)
• Studied: The paediatric otitis media trial gave cefdinir 14 mg/kg once daily, cefdinir 7 mg/kg twice daily, or amoxicillin/clavulanate 13.3 mg/kg three times daily. (Source 26)
• Studied: The 2006 comparison gave 10 days of cefdinir 14 mg/kg divided twice daily against high-dose amoxicillin/clavulanate 90/6.4 mg/kg divided twice daily. (Source 29)
• Studied: The interaction studies used a single 300 mg cefdinir capsule with 30 mL of a magnesium- and aluminium-containing antacid, and with iron supplements containing 60 mg or 10 mg of elemental iron. (Source 7)

A common belief, and what the research shows

The belief: A red or bloody-looking stool in a child on cefdinir means gastrointestinal bleeding.

What the research shows: It is usually iron. The label states: There have been reports of reddish stools in patients receiving cefdinir. In many cases, patients were also receiving iron-containing products. The reddish color is due to the formation of a nonabsorbable complex between cefdinir or its breakdown products and iron in the gastrointestinal tract. In a published case the stools were guaiac negative, recurred on rechallenge, and resolved within hours of stopping the drug. Genuine bloody diarrhoea after an antibiotic is a different matter and can mean C. difficile colitis, which the label says can start more than two months after the last dose.

Questions and answers

What is it?

Cefdinir is an antibiotic - a semisynthetic, extended-spectrum cephalosporin taken by mouth. It comes as 300 mg capsules and as a powder for oral suspension for children. It is a beta-lactam, chemically related to penicillin, and physically a white to slightly brownish-yellow solid. (Source 30)

What does it do in the body?

It kills bacteria by stopping them building their cell wall, the way other cephalosporins do. It survives attack by some bacterial beta-lactamase enzymes but not all, which is why some bacteria that resist penicillins are still killed by it, while Pseudomonas, Enterobacter, enterococci, penicillin-resistant streptococci and MRSA are not. (Source 1)

Is it good or bad for you?

Good when there is a bacterial infection that needs treating, and a net harm when there is not. The Cochrane review of ear infection in children puts the trade-off plainly: a modest effect on pain and perforation, against one extra child in fourteen getting vomiting, diarrhoea or rash. Most ear infections, sinus infections and sore throats in high-income countries resolve on their own, and the reviewers judged an expectant approach justified for most children with mild disease. (Source 31)

How do you get more of it?

Does not apply in the way it would for a nutrient: cefdinir is a prescription antibiotic, not something found in food. What does change how much reaches the bloodstream is timing with other things taken by mouth - iron and magnesium- or aluminium-containing antacids cut absorption sharply, and the label advises separating them from cefdinir by at least two hours. Only about a fifth of a dose is absorbed even without interference. (Source 10)

If it is harmful, what reduces it?

Cefdinir is cleared by the kidneys and leaves the body within a day or so of the last dose; it does not accumulate with once- or twice-daily dosing in people with normal kidney function. The label says to discontinue it if an allergic reaction occurs, and that ongoing antibacterial use not directed against C. difficile may need to be stopped if C. difficile diarrhoea is suspected or confirmed. (Source 13)

Why might someone be low in it or missing it?

Not a nutrient, so 'low' means less drug absorbed than intended. The documented causes are co-administration: a magnesium- or aluminium-containing antacid cuts absorption by about 40%, a 60 mg elemental iron supplement by 80%, and an iron-containing multivitamin by 31%. Absorption is also incomplete to begin with, and falls further as the dose rises. (Source 7)

Which whole foods contain it or feed it?

No whole food contains cefdinir. Food matters only through absorption: a high-fat meal lowers the peak level by 16% and total exposure by 10%, which the label calls unlikely to be clinically significant, so cefdinir may be taken with or without food. Iron-fortified foods such as breakfast cereals are a theoretical concern that has not been studied. (Source 10)

What happens if you do not have it?

Not having cefdinir is not a deficiency; what matters is whether the infection needed an antibiotic. In high-income countries most acute otitis media remits on its own without complications, about 80% of adults with acute sinusitis improve within two weeks untreated, and 82% of people with sore throat are symptom-free within a week on placebo. Where an antibiotic is genuinely needed, the untreated risks are the suppurative and non-suppurative complications the sore-throat review measured. (Source 31)

How can you test for it?

There is no routine blood level test for cefdinir. The relevant testing is of the bacteria, not the drug: the label says culture and susceptibility information should be considered when available in choosing or changing therapy, and that cefdinir should be used only for infections proven or strongly suspected to be bacterial. Note that cefdinir itself can make a urine glucose dipstick read falsely positive and can occasionally turn a direct Coombs test positive. (Source 5)

References

1. DailyMed Structured Product Label (Lupin Pharmaceuticals, Inc.). Cefdinir Capsules USP - CLINICAL PHARMACOLOGY, Microbiology (Mechanism of Action and Resistance). 2025. Read the source
2. The Cochrane database of systematic reviews. Antibiotics for acute otitis media in children.. 2023. PMID 37965923, DOI 10.1002/14651858.CD000219.pub5. Read the source
3. The Cochrane database of systematic reviews. Antibiotics for treatment of sore throat in children and adults.. 2021. PMID 34881426, DOI 10.1002/14651858.CD000023.pub5. Read the source
4. The Cochrane database of systematic reviews. Antibiotics for acute maxillary sinusitis in adults.. 2014. PMID 24515610, DOI 10.1002/14651858.CD000243.pub3. Read the source
5. DailyMed Structured Product Label (Lupin Pharmaceuticals, Inc.). Cefdinir Capsules USP - INDICATIONS AND USAGE. 2025. Read the source
6. DailyMed Structured Product Label (Lupin Pharmaceuticals, Inc.). Cefdinir Capsules USP - PRECAUTIONS, Drug Interactions: Iron Supplements and Foods Fortified With Iron. 2025. Read the source
7. DailyMed Structured Product Label (Lupin Pharmaceuticals, Inc.). Cefdinir Capsules USP - PRECAUTIONS, Drug Interactions: Antacids (Aluminum- or Magnesium-Containing). 2025. Read the source
8. DailyMed Structured Product Label (Lupin Pharmaceuticals, Inc.). Cefdinir Capsules USP - PRECAUTIONS, Drug Interactions: Probenecid. 2025. Read the source
9. DailyMed Structured Product Label (Lupin Pharmaceuticals, Inc.). Cefdinir Capsules USP - PRECAUTIONS, Drug/Laboratory Test Interactions. 2025. Read the source
10. DailyMed Structured Product Label (Lupin Pharmaceuticals, Inc.). Cefdinir Capsules USP - CLINICAL PHARMACOLOGY, Absorption. 2025. Read the source
11. DailyMed Structured Product Label (Lupin Pharmaceuticals, Inc.). Cefdinir Capsules USP - PRECAUTIONS, Information for Patients. 2025. Read the source
12. The Lancet. Infectious diseases. The evidence base for the optimal antibiotic treatment duration of upper and lower respiratory tract infections: an umbrella review.. 2025. PMID 39243792, DOI 10.1016/S1473-3099(24)00456-0. Read the source
13. DailyMed Structured Product Label (Lupin Pharmaceuticals, Inc.). Cefdinir Capsules USP - WARNINGS, Clostridium difficile associated diarrhea. 2025. Read the source
14. The Journal of pediatrics. Adverse Events of Antibiotics Used to Treat Acute Otitis Media in Children: A Systematic Meta-Analysis.. 2019. PMID 31561959, DOI 10.1016/j.jpeds.2019.08.043. Read the source
15. The Journal of antimicrobial chemotherapy. Antibiotics and healthcare facility-associated Clostridioides difficile infection: systematic review and meta-analysis 2020 update.. 2021. PMID 33787887, DOI 10.1093/jac/dkab091. Read the source
16. The journal of allergy and clinical immunology. In practice. Cross-Reactivity to Cephalosporins and Carbapenems in Penicillin-Allergic Patients: Two Systematic Reviews and Meta-Analyses.. 2019. PMID 31170539, DOI 10.1016/j.jaip.2019.05.038. Read the source
17. Pharmacotherapy. Nonbloody, red stools from coadministration of cefdinir and iron-supplemented infant formulas.. 2008. PMID 18447664, DOI 10.1592/phco.28.5.678. Read the source
18. DailyMed Structured Product Label (Lupin Pharmaceuticals, Inc.). Cefdinir Capsules USP - ADVERSE EVENTS, Clinical Trials (Adult and Adolescent Patients). 2025. Read the source
19. DailyMed Structured Product Label (Lupin Pharmaceuticals, Inc.). Cefdinir Capsules USP - ADVERSE EVENTS, Postmarketing Experience. 2025. Read the source
20. The Cochrane database of systematic reviews. Antibiotics for acute otitis media in children (null outcomes and immediate antibiotics versus expectant observation). 2023. PMID 37965923, DOI 10.1002/14651858.CD000219.pub5. Read the source
21. Current medical research and opinion. Efficacy, tolerability, and parent reported outcomes for cefdinir vs. high-dose amoxicillin/clavulanate oral suspension for acute otitis media in young children.. 2006. PMID 16968587, DOI 10.1185/030079906X132406. Read the source
22. The Cochrane database of systematic reviews. Antibiotics for treatment of sore throat in children and adults (suppurative and non-suppurative complications). 2021. PMID 34881426, DOI 10.1002/14651858.CD000023.pub5. Read the source
23. The Turkish journal of pediatrics. Efficacy of antimicrobials or placebo compared to amoxicillin-clavulanate in children with acute otitis media: a systematic review.. 2023. PMID 37395955, DOI 10.24953/turkjped.2022.893. Read the source
24. The Cochrane database of systematic reviews. Antibiotics for acute maxillary sinusitis in adults (authors' conclusions). 2014. PMID 24515610, DOI 10.1002/14651858.CD000243.pub3. Read the source
25. The Cochrane database of systematic reviews. Antibiotics for treatment of sore throat in children and adults.. 2021. PMID 34881426, DOI 10.1002/14651858.CD000023.pub5. Read the source
26. The Pediatric infectious disease journal. Cefdinir vs. amoxicillin/clavulanic acid in the treatment of suppurative acute otitis media in children.. 2000. PMID 11144399, DOI 10.1097/00006454-200012001-00006. Read the source
27. DailyMed Structured Product Label (Lupin Pharmaceuticals, Inc.). Cefdinir Capsules USP - WARNINGS, hypersensitivity. 2025. Read the source
28. DailyMed Structured Product Label (Lupin Pharmaceuticals, Inc.). Cefdinir Capsules USP - DOSAGE AND ADMINISTRATION. 2025. Read the source
29. Current medical research and opinion. Efficacy, tolerability, and parent reported outcomes for cefdinir vs. high-dose amoxicillin/clavulanate oral suspension for acute otitis media in young children (design). 2006. PMID 16968587, DOI 10.1185/030079906X132406. Read the source
30. DailyMed Structured Product Label (Lupin Pharmaceuticals, Inc.). Cefdinir Capsules USP - DESCRIPTION. 2025. Read the source
31. The Cochrane database of systematic reviews. Antibiotics for acute otitis media in children (authors' conclusions). 2023. PMID 37965923, DOI 10.1002/14651858.CD000219.pub5. Read the source