Ciprofloxacin

What it is

Ciprofloxacin is a synthetic fluoroquinolone antibacterial, given as film-coated tablets, by vein, and as eye and ear drops. The oral tablets contain the monohydrochloride monohydrate salt and come in 250 mg, 500 mg and 750 mg strengths. It was first approved in the United States in 1987 and carries a boxed warning covering tendon rupture, nerve damage, central nervous system effects and myasthenia gravis.

What the research says

Ciprofloxacin kills bacteria by blocking the enzymes they need to copy their DNA. For simple bladder infection it works: a randomised trial in 688 evaluable women found a 3-day course eradicated the pathogen in 94% of those given ciprofloxacin, much the same as trimethoprim/sulfamethoxazole. The reason it is nonetheless a reserve drug for that infection is harm. The boxed warning names tendinitis and tendon rupture, peripheral neuropathy and central nervous system effects as disabling and potentially irreversible. A Swedish cohort of 360,088 treatment episodes, 78% of them ciprofloxacin, found 1.2 aortic aneurysm or dissection cases per 1,000 person-years versus 0.7 on amoxicillin. For a long-standing pelvic pain syndrome it is commonly prescribed for, a randomised trial found it no better than placebo.

Evidence grade: Well established.

How it works

Drug class: Fluoroquinolone antibacterial

Ciprofloxacin blocks two bacterial enzymes, DNA gyrase (topoisomerase II) and topoisomerase IV, that bacteria need to unwind and copy their DNA. Without them the bacterium cannot replicate, transcribe or repair its DNA, and it dies. Human cells do not use these bacterial enzymes, which is why the drug is selective for bacteria. Resistance arises mainly through mutations in the gyrases, reduced permeability of the bacterial outer membrane, or pumps that push the drug back out. (Source 1)

Boxed warning

WARNING: SERIOUS ADVERSE REACTIONS INCLUDING TENDINITIS, TENDON RUPTURE, PERIPHERAL NEUROPATHY, CENTRAL NERVOUS SYSTEM EFFECTS AND EXACERBATION OF MYASTHENIA GRAVIS

(Source 2)

What it is used for

• A 3-day course eradicated the pathogen in 94% of 229 ciprofloxacin-treated women in a randomised double-blind trial, with 93% clinical success - essentially the same as trimethoprim/sulfamethoxazole. Because of the class harms, and because the condition is often self-limiting, the label now reserves ciprofloxacin for patients with no alternative treatment option. Evidence: established. (Source 3)
• Licensed, but the label itself states ciprofloxacin is not a first-choice drug in children because of a higher rate of adverse reactions than controls, including joint-related ones. A 2021 meta-analysis of 5 randomised studies in 2,877 patients found no significant efficacy difference between levofloxacin and ciprofloxacin. Evidence: established. (Source 4)
• These are licensed uses recorded on the FDA label as of its 2026-05-11 version. For most of them we did not find a current systematic review giving absolute cure rates against comparators, so the label should be read as a regulatory position rather than as a summary of outcome-trial evidence. Evidence: limited. (Source 5)
• A randomised, double-blind, 2x2 factorial trial in 196 men with a mean 6.2 years of symptoms found six weeks of ciprofloxacin no better than no ciprofloxacin on the primary symptom score (P = 0.15) or on any secondary outcome. Evidence: not-supported. (Source 6)
• A randomised double-blind pilot trial in 79 otherwise healthy women found 58.3% symptom-free on day 4 with ibuprofen versus 51.5% with ciprofloxacin, but a third of the ibuprofen group needed a rescue antibiotic versus 18% of the ciprofloxacin group. The authors call it a pilot needing confirmation. Evidence: disputed. (Source 7)

Interactions

• Milk, yogurt and calcium-fortified juices (pharmacokinetic study): Dairy taken at the same time as ciprofloxacin binds the drug in the gut so less of it is absorbed. A crossover study in healthy volunteers found peak blood levels fell 36% with milk and 47% with yogurt and total absorption fell by about a third. The label says dairy alone should be avoided with the tablet, though taking it with a meal containing dairy is acceptable. (Source 8)
• Milk and yogurt - what the label directs (label): The label's own instruction is to avoid taking the tablet with dairy products or calcium-fortified juices alone, while allowing it with a meal that contains them. (Source 9)
• Calcium, iron and zinc supplements, multivitamins with minerals, and magnesium/aluminium antacids (label): Multivalent metal ions bind ciprofloxacin in the gut and cut its absorption. The label directs that the tablet be taken at least 2 hours before or 6 hours after any of these. (Source 9)
• Caffeine (coffee, tea, cola, caffeine supplements) and other xanthines (pharmacokinetic study): Ciprofloxacin slows the enzyme that clears caffeine, so caffeine lingers. In ten healthy men, ciprofloxacin lengthened caffeine's half-life from 5.2 to 8.2 hours and nearly halved its clearance. The label advises caution and monitoring for xanthine toxicity. (Source 10)
• Caffeine - what the label directs (label): The label lists caffeine and xanthine derivatives under use with caution, noting reduced clearance, raised levels and a longer half-life. (Source 11)
• Tizanidine (label): Combining the two is contraindicated: ciprofloxacin raises tizanidine levels and potentiates its blood-pressure-lowering and sedating effects. (Source 12)
• Theophylline (label): Ciprofloxacin raises and prolongs theophylline levels, increasing the risk of central nervous system and other adverse reactions. The label says to avoid the combination. (Source 12)
• Warfarin and other oral anticoagulants (label): The anticoagulant effect can increase. The label notes the contribution of ciprofloxacin itself is hard to separate from the effect of the underlying infection, and directs frequent INR monitoring. (Source 13)
• Sulfonylureas and other oral diabetes drugs (case reports): Hypoglycaemia, sometimes severe and sometimes fatal, has been reported when ciprofloxacin is combined with oral antidiabetic agents, mainly sulfonylureas such as glyburide and glimepiride. (Source 14)
• Drugs that prolong the QT interval (label): Ciprofloxacin may add to QT prolongation from class IA or III antiarrhythmics, tricyclic antidepressants, macrolides and antipsychotics; the label says to avoid the combination. (Source 14)
• Non-steroidal anti-inflammatory drugs (label): Very high quinolone doses with NSAIDs (but not aspirin) have provoked convulsions in preclinical studies and in postmarketing reports. (Source 11)
• Alcohol (label): No alcohol interaction is documented in either the drug interactions section or the administration instructions of the label we read. The administration guidance that is given concerns multivalent cations and dairy, and hydration. We found no pharmacokinetic study of ciprofloxacin with ethanol in our searches, so we record this as an absence of evidence rather than evidence of safety. (Source 9)

Stopping it

• Ciprofloxacin is a short antibacterial course and no dependence or withdrawal syndrome is described in the literature we searched. The stopping instruction in the boxed warning runs the other way: it directs that the drug be stopped at once, and fluoroquinolones avoided afterwards, in anyone who develops tendinitis, tendon rupture, peripheral neuropathy or central nervous system effects. (Source 2)
• For tendon problems specifically the label gives a time course that extends well past the last dose: tendinitis or rupture can occur within hours or days of starting, or as long as several months after the course has finished, and can affect both sides. (Source 15)
• For nerve symptoms the label directs immediate discontinuation to limit permanent damage, and states that symptoms may be irreversible in some patients. (Source 16)
• Stopping early has its own cost. The label states a course should generally continue for at least two days after the signs and symptoms of infection have gone, except for inhalational anthrax, and that under-treatment lets resistant bacteria emerge. (Source 5)

What goes wrong

Fluoroquinolone use was associated with an increased rate of aortic aneurysm or dissection within 60 days in a nationwide cohort of 360,088 treatment episodes. (Source 17)

• Cohort study, Moderate certainty.
• Size: 360,088 fluoroquinolone treatment episodes (78% ciprofloxacin) and 360,088 propensity-score-matched amoxicillin episodes.
• Who: Swedish population, July 2006 to December 2013.
• How long: 60-day risk window from start of treatment.
• Result: 1.2 cases per 1,000 person-years on fluoroquinolones versus 0.7 on amoxicillin; hazard ratio 1.66 (95% CI 1.12 to 2.46); estimated absolute difference 82 cases (95% CI 15 to 181) per 1 million treatment episodes by 60 days. Driven mainly by aneurysm (HR 1.90) rather than dissection (HR 0.93). This is an observational association, not a demonstrated cause.
• Funding: not stated in the abstract.

Within the 60 day risk period, the rate of aortic aneurysm or dissection was 1.2 cases per 1000 person years among fluoroquinolone users and 0.7 cases per 1000 person years among amoxicillin users. Fluoroquinolone use was associated with an increased risk of aortic aneurysm or dissection (hazard ratio 1.66 (95% confidence interval 1.12 to 2.46)), with an estimated absolute difference of 82 (95% confidence interval 15 to 181) cases of aortic aneurysm or dissection by 60 days per 1 million treatment episodes.

Current oral fluoroquinolone use was associated with peripheral neuropathy, but the absolute risk was very small. (Source 18)

• Case-control study, Moderate certainty.
• Size: 5,357 patients with incident peripheral neuropathy matched to 17,285 controls, from a cohort of 1,338,900 adults.
• Who: UK primary care patients without diabetes prescribed a fluoroquinolone (34.3%) or amoxicillin-clavulanate (65.7%), 1999 to 2015.
• How long: Current and cumulative exposure, with risk persisting up to 180 days after exposure.
• Result: Adjusted incident rate ratio 1.47 (95% CI 1.13-1.92) for current fluoroquinolone exposure versus none; absolute risk 2.4 (95% CI 1.8-3.1) per 10,000 patients per year of current use; number needed to harm for a 10-day course 152,083 patients (95% CI 117,742-202,778). No significant increase with amoxicillin-clavulanate.
• Funding: not stated in the abstract.

The absolute risk with current oral fluoroquinolone exposure was 2.4 (95% CI, 1.8-3.1) per 10 000 patients per year of current use. The number needed to harm for a 10-day course was 152 083 patients (95% CI, 117 742-202 778) and was greatest among men and among patients older than 60 years.

Across 12 studies of 439,299 patients, the Achilles tendon complication rate with ciprofloxacin was 0.17%, lower than with ofloxacin. (Source 19)

• Meta-analysis, Low certainty.
• Size: 12 studies, 439,299 patients (59.7% women, 40.3% men, mean age 53.0 +/- 15.6 years)
• Who: Adults exposed to fluoroquinolones, stratified by molecule.
• How long: Not stated; studies of any level of evidence were included.
• Result: Expected risk of Achilles tendinopathy or rupture 0.17% (95% CI 0.15-0.19) for levofloxacin and 0.17% (95% CI 0.16-0.19) for ciprofloxacin, versus 1.40% (95% CI 0.88-2.03) for ofloxacin and 0.31% (95% CI 0.23-0.40) for other molecules. Levofloxacin and ciprofloxacin did not differ.
• Funding: not stated in the abstract.

The expected risk of AT/ATR was 0.17% (95% CI: 0.15-0.19, standard error (s.e.): 0.24) for levofloxacin, 0.17% (95% CI: 0.16-0.19, s.e.: 0.20) for ciprofloxacin, 1.40% (95% CI: 0.88-2.03, s.e.: 2.51) for ofloxacin, and 0.31% (95% CI: 0.23-0.40, s.e.: 0.77) for the other molecules.

In children treated for complicated urinary tract infection, musculoskeletal adverse reactions were more frequent on ciprofloxacin than on a cephalosporin. (Source 20)

• Randomized trial, Moderate certainty.
• Size: 335 ciprofloxacin-treated and 349 comparator-treated patients.
• Who: Children aged 1 to 17 years (mean 6 +/- 4 years) with complicated UTI or pyelonephritis, international multicentre trial.
• How long: 10 to 21 days of therapy (mean 11 days); follow-up to 1 year.
• Result: Within 6 weeks of starting treatment, musculoskeletal adverse reactions in 9.3% (31/335) on ciprofloxacin versus 6% (21/349) on comparator. At 1 year, 13.7% (46/335) versus 9.5% (33/349). All reactions occurring by 6 weeks resolved, usually within 30 days of ending treatment; radiological confirmation of resolution was not routinely used.
• Funding: Reported in FDA-approved labelling; trial sponsor not stated in the section.

Within 6 weeks of treatment initiation, the rates of musculoskeletal adverse reactions were 9.3% (31/335) in the ciprofloxacin-treated group versus 6% (21/349) in comparator-treated patients.

The most frequent adverse reactions across the whole ciprofloxacin clinical trial programme were gastrointestinal and occurred in a few percent of patients. (Source 21)

• Official position, Low certainty.
• Size: 49,038 patients received courses of oral or parenteral ciprofloxacin during clinical investigations.
• Who: All formulations, all dosages, all durations, all indications.
• How long: Not stated.
• Result: Nausea 2.5%, diarrhoea 1.6%, abnormal liver function tests 1.3%, vomiting 1%, rash 1%. No placebo arm is given for these figures, so they are not placebo-adjusted. A long list of medically important reactions each occurred in less than 1%.
• Funding: FDA-approved labelling.

The most frequently reported adverse reactions, from clinical trials of all formulations, all dosages, all drug-therapy durations, and for all indications of ciprofloxacin therapy were nausea (2.5%), diarrhea (1.6%), liver function tests abnormal (1.3%), vomiting (1%), and rash (1%).

Severe hypoglycaemia leading to coma or death has been reported with ciprofloxacin, mostly in people also taking diabetes medicines. (Source 22)

• Official position, Certainty not rated.
• Size: Not stated.
• Who: Usually diabetic patients receiving an oral hypoglycaemic agent such as glyburide, or insulin.
• How long: Not stated.
• Result: No rate is given. The label states severe cases of hypoglycaemia resulting in coma or death have been reported, and the drug interaction table records fatalities with oral antidiabetic agents, mainly sulfonylureas.
• Funding: FDA-approved labelling.

Severe cases of hypoglycemia resulting in coma or death have been reported.

The label records that epidemiologic studies find an increased rate of aortic aneurysm and dissection within two months of fluoroquinolone use, without an identified cause. (Source 23)

• Official position, Certainty not rated.
• Size: Not stated in the section.
• Who: Fluoroquinolone users, particularly elderly patients.
• How long: Within two months following use.
• Result: No rate is given in this section. The label directs that in people with a known aortic aneurysm or at greater risk of one, ciprofloxacin be reserved for when no alternative is available.
• Funding: FDA-approved labelling.

Epidemiologic studies report an increased rate of aortic aneurysm and dissection within two months following use of fluoroquinolones, particularly in elderly patients.

Milk and yogurt substantially reduced how much ciprofloxacin reached the bloodstream in a crossover study of healthy volunteers. (Source 8)

• Blood level study, Low certainty.
• Size: 7 healthy volunteers, randomised crossover.
• Who: Healthy volunteers given 500 mg ciprofloxacin after an overnight fast with 300 ml of water, milk or yogurt.
• How long: Single dose, plasma sampled to 10 hours and urine to 24 hours.
• Result: At half an hour the plasma concentration was reduced by 70% by milk and 92% by yogurt; peak concentration fell 36% with milk and 47% with yogurt; total bioavailability by area under the curve and 24-hour urinary excretion fell by 30% to 36% (all p less than 0.05).
• Funding: not stated in the abstract.

at 1/2 hour the concentration was reduced by 70% by milk and by 92% by yogurt. Milk reduced the peak plasma concentration by 36% (p less than 0.05) and yogurt by 47% (p less than 0.05). The extent of bioavailability, measured as the total area under the plasma concentration-time curve and 24-hour urinary excretion of ciprofloxacin, was reduced by 30% to 36% by milk and yogurt (p less than 0.05).

What the evidence supports

A three-day course of ciprofloxacin eradicated the causative bacteria in 94% of women with uncomplicated urinary tract infection, no better and no worse than the comparators. (Source 3)

• Randomized trial, Moderate certainty.
• Size: 866 enrolled, 688 (79%) evaluable for efficacy: 229 ciprofloxacin, 228 trimethoprim/sulfamethoxazole, 231 ofloxacin.
• Who: Women with acute, uncomplicated, symptomatic lower urinary tract infection; E. coli in 81%.
• How long: 3 days of treatment; follow-up at 4 to 6 weeks.
• Result: Eradication at end of therapy 94% ciprofloxacin, 93% trimethoprim/sulfamethoxazole, 97% ofloxacin. Clinical success 93%, 95% and 96%. Recurrence at 4 to 6 weeks 11%, 16% and 13%. All adverse events 31% ciprofloxacin versus 41% trimethoprim/sulfamethoxazole and 39% ofloxacin (P = 0.03).
• Funding: Not stated in the abstract; the author group is named the Ciprofloxacin Urinary Tract Infection Group, which a reader should weigh.

Eradication of the pretreatment pathogen at the end of therapy occurred in 94% of ciprofloxacin, 93% of trimethoprim/sulfamethoxazole, and 97% of ofloxacin-treated patients.

What the evidence does not support

Ciprofloxacin was no better than placebo for chronic prostatitis / chronic pelvic pain syndrome. (Source 6)

• Randomized trial, Moderate certainty.
• Size: 196 men.
• Who: Men at 10 North American tertiary urology centres with NIH Chronic Prostatitis Symptom Index score of at least 15 and a mean of 6.2 years of symptoms, substantially pretreated.
• How long: 6 weeks of therapy.
• Result: No statistically significant difference for ciprofloxacin versus no ciprofloxacin on the primary NIH-CPSI total score (P = 0.15); treatments also did not differ significantly on any secondary outcome. Scores fell modestly in all four groups.
• Funding: not stated in the abstract.

No statistically significant difference in the primary outcome was seen for ciprofloxacin versus no ciprofloxacin (P = 0.15) or tamsulosin versus no tamsulosin (P > 0.2). Treatments also did not differ significantly for any of the secondary outcomes.

Where the evidence is mixed

Levofloxacin and ciprofloxacin did not differ significantly in efficacy or adverse reactions for urinary tract infection. (Source 24)

• Meta-analysis, Low certainty.
• Size: 5 studies, 2,877 patients.
• Who: Patients with urinary tract infection in randomised comparative studies.
• How long: Not stated.
• Result: Odds ratio for efficacy 1.18 (95% CI 0.94 to 1.46, P = 0.15) favouring levofloxacin but not significant; adverse reaction rate OR 0.91 (95% CI 0.78 to 1.07, P = 0.27).
• Funding: not stated in the abstract.

The results showed that levofloxacin was more effective than ciprofloxacin, but the difference between the 2 drugs was not statistically significant [odds ratio (OR) =1.18, 95% confidence interval (CI): 0.94 to 1.46, P=0.15].

Ibuprofen was not clearly worse than ciprofloxacin for symptom resolution in simple urinary tract infection in a small pilot trial, but more ibuprofen patients needed a rescue antibiotic. (Source 7)

• Randomized trial, Very low certainty.
• Size: 79 analysed (ibuprofen n = 40, ciprofloxacin n = 39) in 29 German general practices.
• Who: Otherwise healthy women aged 18 to 85 with dysuria or frequency and no complicating factors.
• How long: 3 days of treatment; symptoms scored on days 4, 7 and 28.
• Result: Symptom-free on day 4: 21/36 (58.3%) ibuprofen versus 17/33 (51.5%) ciprofloxacin. Secondary antibiotic treatment during days 0 to 9: 12/36 (33%) ibuprofen versus 6/33 (18%) ciprofloxacin (non significant). 58 non-serious adverse events, 32 ibuprofen versus 26 ciprofloxacin. The authors describe it as a pilot needing confirmation.
• Funding: not stated in the abstract.

Limit of this finding: The numbers in this abstract do not share one denominator. It says 79 patients were analysed, 40 on ibuprofen and 39 on ciprofloxacin, but every result is then given out of 36 and 33, the smaller per-protocol groups. The trial also set an equivalence margin of plus or minus 0.5 symptom-score points in advance, and the confidence interval it reports, -1,13 to +0,47, is wider than that, so the data do not actually fall inside the margin the authors set. The commas in the numbers are the authors' own decimal separators.

During Days 0 and 9, 12/36 (33%) of patients in the ibuprofen-group received secondary antibiotic treatment due to ongoing or worsening symptoms, compared to 6/33 (18%) in the ciprofloxacin-group (non significant).

Where the research disagrees

How much the tendon risk differs between fluoroquinolones, and how big it is in absolute terms

• The FDA-approved US label for ciprofloxacin tablets, version dated 2026-05-11, Regulatory position; no incidence figure is given in the section: Fluoroquinolones, including ciprofloxacin, have been associated with an increased risk of tendinitis and tendon rupture in all ages (Source 15)
• A 2024 molecule-stratified systematic review and meta-analysis in EFORT Open Reviews, Meta-analysis of 12 studies in 439,299 patients, stratified by molecule, rated overall good quality by the authors: Ofloxacin demonstrated a significantly higher rate of AT/ATR complications in the adult population, while levofloxacin and ciprofloxacin showed a safer profile (Source 19)

How much

• Reference intake: Dosing is set by the prescriber. The FDA label records, as a position in its 2026-05-11 version, adult regimens of 250 to 500 mg every 12 hours for 7 to 14 days for urinary tract infections, 250 mg every 12 hours for 3 days for acute uncomplicated cystitis, 500 mg every 12 hours for 28 days for chronic bacterial prostatitis, and 500 mg every 12 hours for 60 days for inhalational anthrax post-exposure. (Source 5)
• Upper limit: The highest adult dose in the label's table is 750 mg every 12 hours, used for skin and skin structure, bone and joint, plague and lower respiratory tract infections. This is a label position, not a tolerable upper intake level, and the label separately directs dose reduction in renal impairment. (Source 5)
• Studied: The 1999 randomised uncomplicated-UTI trial gave ciprofloxacin 100 mg twice daily for 3 days. (Source 25)
• Studied: The chronic pelvic pain syndrome trial gave ciprofloxacin 500 mg twice daily for 6 weeks. (Source 6)
• Studied: The dairy interaction study gave a single 500 mg dose with 300 ml of water, milk or yogurt. (Source 8)

A common belief, and what the research shows

The belief: Ciprofloxacin is a routine first-line antibiotic for a simple bladder infection.

What the research shows: It works for that infection - a randomised trial found "Eradication of the pretreatment pathogen at the end of therapy occurred in 94% of ciprofloxacin" patients - but the label has since reclassified it as a reserve drug for that use, saying "for some patients acute uncomplicated cystitis is self-limiting, reserve ciprofloxacin tablets for treatment of acute uncomplicated cystitis in patients who have no alternative treatment options." The boxed warning gives the reason: fluoroquinolones "have been associated with disabling and potentially irreversible serious adverse reactions that have occurred together". The absolute risks are small - 2.4 peripheral neuropathy cases per 10,000 patients per year of current use, and 82 extra aortic events per million treatment episodes - but they are set against a condition that often resolves without an antibiotic at all.

Questions and answers

What is it?

Ciprofloxacin is a synthetic fluoroquinolone antibacterial made for swallowing as a film-coated tablet, and also available as an injection and as eye and ear drops. The oral form is the hydrochloride salt of a quinolinecarboxylic acid, a faintly yellow crystalline substance. It was first approved in the United States in 1987. (Source 26)

What does it do in the body?

Ciprofloxacin kills bacteria by blocking two enzymes, DNA gyrase and topoisomerase IV, that bacteria need in order to copy, read and repair their DNA. With those enzymes blocked the bacterium cannot divide and dies. Human cells do not rely on those bacterial enzymes, which is what makes the drug selective. Bacteria become resistant mainly by mutating the gyrases, by letting less drug in, or by pumping it back out. (Source 1)

Is it good or bad for you?

It is effective and it is risky, and the balance depends on the infection. For a simple bladder infection a 3-day course cleared the bacteria in 94% of women in a randomised trial - but the label now reserves it for that use because of the harms. The boxed warning names tendinitis and tendon rupture, nerve damage and central nervous system effects as potentially irreversible. The absolute risks are low (2.4 peripheral neuropathy cases per 10,000 patients per year of current use), but for a self-limiting infection they are not worth running. (Source 4)

How do you get more of it?

Ciprofloxacin is a prescription-only antibacterial, not a nutrient, so there is no food source and no reason to seek more of it. The amount is set by a prescriber; the label records, as a position, 250 to 500 mg every 12 hours for 7 to 14 days for urinary tract infections. It also states the drug should be used only for infections proven or strongly suspected to be caused by susceptible bacteria. (Source 4)

If it is harmful, what reduces it?

The drug clears from the body within a day or so of the last dose, and the label directs that it be stopped immediately if tendon pain, swelling or nerve symptoms appear. Stopping is what limits the damage: for nerve symptoms the label says to discontinue immediately in order to minimise the development of an irreversible condition. Nothing accelerates clearance; adequate hydration is advised to avoid crystals forming in concentrated urine. (Source 16)

Why might someone be low in it or missing it?

This does not apply in the nutrient sense. Blood levels can be lower than intended for a specific and common reason: taking the tablet with dairy or with calcium, iron or zinc. In a crossover study, half an hour after dosing the blood level was 70% lower with milk and 92% lower with yogurt, and total absorption fell by about a third. The label therefore spaces the tablet at least 2 hours before or 6 hours after mineral-containing products. (Source 8)

Which whole foods contain it or feed it?

No whole food contains ciprofloxacin. The food question that matters is which foods block it: milk, yogurt and calcium-fortified juices reduce its absorption and the label says to avoid taking the tablet with them alone, though a meal containing them is acceptable. Caffeine runs the other way - ciprofloxacin slows caffeine clearance, lengthening its half-life from 5.2 to 8.2 hours in a volunteer study. (Source 9)

What happens if you do not have it?

Nothing happens from not having ciprofloxacin unless a susceptible infection is present and needs treating. For a simple bladder infection the alternative is often another antibiotic of similar efficacy: in a randomised trial, trimethoprim/sulfamethoxazole eradicated the pathogen in 93% versus 94% for ciprofloxacin. For anthrax exposure or plague, where the label gives 60-day and 14-day regimens, the stakes of having no effective antibacterial are obviously different. (Source 3)

How can you test for it?

There is no routine blood test for ciprofloxacin levels in ordinary care. What is tested is the bacterium: the label directs that appropriate culture and susceptibility tests be performed before treatment to identify the organism and determine whether it is susceptible, and that therapy may be started before the results are back and then adjusted. Repeat testing during therapy can also show resistance emerging, which the label notes happens fairly rapidly with some Pseudomonas aeruginosa isolates. (Source 4)

References

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