Sulfacetamide; Sulfur

What it is

This is a prescription cream, lotion, cleanser or foam applied to the skin, not a tablet. Each gram of the 10%/5% cream contains 100 mg of sodium sulfacetamide and 50 mg of sulfur. Sodium sulfacetamide is a sulfonamide, chemically N-[(4-aminophenyl) sulfonyl]-acetamide, monosodium salt, monohydrate; sulfur is the elemental keratolytic. The combination has been in use since the mid-1950s.

What the research says

It is labelled for the topical control of acne vulgaris, acne rosacea and seborrheic dermatitis. The evidence behind those three uses is much weaker than the length of its history suggests. One investigator-blinded randomised trial in rosacea compared it with topical metronidazole and favoured it on several measures. Beyond that, the modern systematic reviews of rosacea treatments found the sodium sulfacetamide with sulfur studies were at unclear-to-high risk of bias, inadequately reported or provided very limited data, and the acne and seborrhoeic dermatitis figures that get quoted come from uncontrolled studies and case series, several of them from the 1950s. We found no placebo-controlled randomised trial of this combination in any of its three labelled uses.

Evidence grade: Limited evidence.

How it works

Drug class: Topical combination of a sulfonamide antibacterial (sodium sulfacetamide) with a keratolytic (sulfur)

Sodium sulfacetamide blocks bacterial growth by competing with para-aminobenzoic acid, which bacteria need to make folate; the label says this is believed to be the mechanism. Sulfur is a keratolytic, thought to work by reacting with the cysteine in skin cells, and in combination with sulfacetamide has been reported to inhibit the acne bacterium. About 1% of topically applied sulfur is estimated to be absorbed; absorption of sodium sulfacetamide through intact skin has not been determined. (Source 1)

What it is used for

• One investigator-blinded randomised trial in 152 people found the 10%/5% cream with sunscreens beat metronidazole 0.75% cream on inflammatory lesion reduction (80% vs 72%, P = .04), erythema improvement (69% vs 45%, P = .0007) and global improvement (79% vs 59%, P = .01), but not on investigator global severity. A later systematic review of 152 rosacea studies judged the sodium sulfacetamide with sulfur evidence to be at unclear-to-high risk of bias or too limited to use, so this combination does not appear in the graded recommendations. Evidence: limited. (Source 2)
• A narrative review reports that twice-daily use for 12 weeks decreases inflammatory acne lesions by 80.4% to 83%, but those figures come from studies without a placebo comparison. The most recent published clinical report we found for the emollient foam in acne is a case report series, written by an author who discloses consultancy and research relationships with many dermatology companies. Evidence: limited. (Source 3)
• The quoted evidence is uncontrolled. A narrative review reports one study in which the condition was improved or completely controlled in 93% (71/76) of cases with sodium sulfacetamide ointment and soap, and a lotion study effective in 89% (54/61) of patients with scalp involvement and 68% (30/44) with glabrous skin involvement. Neither had a control group. Evidence: limited. (Source 3)
• A narrative review reports that topical sodium sulfacetamide with oral tetracyclines consistently clears lesions in most patients, but says directly that there have been no well-controlled trials comparing it with other topical therapies for this condition. Evidence: limited. (Source 4)

Interactions

• Other sulfonamide drugs, and a reported 'sulfa allergy' (case reports): The product is contraindicated in anyone with known hypersensitivity to sulfonamides or sulfur. In the rosacea trial, seven subjects tolerated it poorly, which the authors suggested might be sulfa drug allergy. A large database study found that a prior sulfonamide-antibiotic reaction does not mean true cross-reactivity with non-antibiotic sulfonamides - it mostly marks a general tendency to drug allergy - so a 'sulfa allergy' label should not be assumed to apply to every sulfur-containing or sulfonamide-named product. (Source 5)
• Kidney disease (label): Not a drug interaction as such, but the label bars use in people with kidney disease alongside the sulfonamide hypersensitivity contraindication. (Source 6)
• Broken, denuded or abraded skin (label): The label asks for particular caution where skin is broken, which is the situation in which systemic absorption of a topical sulfonamide would be greatest. No absorption figure for sodium sulfacetamide through broken skin is given. (Source 7)
• Retinoids and benzoyl peroxide used on the same skin (case reports): A narrative review notes sodium sulfacetamide is not associated with the excessive erythema and irritation often seen with retinoic acid and benzoyl peroxide. In the published acne case series it was used alongside tretinoin, tazarotene or benzoyl peroxide, with dryness and redness reported in several patients. (Source 4)

Stopping it

• There is no taper and no withdrawal syndrome. The label's instruction is to stop if irritation develops and treat the irritation, and to watch for local irritation or sensitisation during long-term use. (Source 8)
• Because rosacea is a chronic facial dermatosis, treatment controls it rather than curing it, so stopping can be expected to be followed by return of the condition. We found no trial that measured relapse after stopping this specific combination. (Source 9)

What goes wrong

Seven people in the trial tolerated the sulfacetamide-sulfur cream poorly, which the authors attribute to possible sulfa drug allergy. (Source 2)

• Randomized trial, Low certainty.
• Size: 7 of 75 subjects on the sulfacetamide-sulfur cream.
• Who: People with rosacea.
• How long: 12 weeks.
• Result: Overall tolerance was good or excellent in 85% of the sulfacetamide-sulfur group and 97% of the metronidazole group; 7 subjects had poor tolerance.
• Funding: not stated: the abstract carries no funding statement and the bibliographic record has none, and the trial compared two branded products.

Limit of this finding: This trial points two ways at once, and both directions are its own result. It favoured the sulfacetamide and sulfur cream on lesion counts, erythema and global improvement, and at the same time found the comparator cream better tolerated: overall tolerance was good or excellent in 97% of the metronidazole group against 85% of the sulfacetamide and sulfur group, and seven of its users tolerated it poorly. So the efficacy result is not a reason to read this as the gentler of the two creams. It was also randomised but only investigator-blinded, with an active comparator and no placebo arm, so neither arm's numbers measure anything against no treatment.

Seven subjects had poor tolerance to the sodium sulfacetamide 10% and sulfur 5% cream with sunscreens, possibly caused by a sulfa drug allergy.

About one in five patients in one study had a local skin reaction, and serious reactions including Stevens-Johnson syndrome have been reported from ophthalmic sulfacetamide. (Source 10)

• Expert review, not systematic, Low certainty.
• Size: 6/31 patients in the cited study.
• Who: Patients using topical or ophthalmic sodium sulfacetamide.
• How long: not stated.
• Result: 19% (6/31) of patients experienced local reactions, most considered mild. Rare but serious reactions including erythema multiforme and Stevens-Johnson syndrome have been reported from ophthalmic use.
• Funding: not stated.

One study reported that 19% (6/31) of patients experienced local reactions but most were considered mild.9 Rare but serious reactions including erythema multiforme and Stevens-Johnson syndrome have been reported from ophthalmic use.

The label warns that systemic toxic reactions - including agranulocytosis, acute haemolytic anaemia, purpura haemorrhagica, drug fever and jaundice - indicate sulfonamide hypersensitivity, and that caution is needed on broken skin. (Source 7)

• Official position, Certainty not rated.
• Size: not quantified.
• Who: People using topical sodium sulfacetamide, especially those prone to sulfonamide hypersensitivity.
• How long: not applicable.
• Result: No rate given. The label describes sensitivity as rare.
• Funding: not applicable.

Systemic toxic reactions such as agranulocytosis, acute hemolytic anemia, purpura hemorrhagica, drug fever, jaundice and contact dermatitis indicate hypersensitivity to sulfonamides.

Reddening and scaling of the skin are expected effects of the combination rather than unusual events, and the label's stated aim is desquamation without irritation. (Source 8)

• Official position, Certainty not rated.
• Size: not quantified.
• Who: People treated for acne vulgaris.
• How long: long-term therapy.
• Result: No rate given. The label states that these side effects are not unusual in the treatment of acne vulgaris.
• Funding: not applicable.

The object of this therapy is to achieve desquamation without irritation, but sodium sulfacetamide and sulfur can cause reddening and scaling of the epidermis.

What the evidence supports

In a randomised but only investigator-blinded trial with no placebo group, the 10%/5% cream with sunscreens reduced inflammatory rosacea lesions more than metronidazole 0.75% cream over 12 weeks, while the metronidazole cream was the better tolerated of the two (overall tolerance good or excellent in 97% of its users versus 85%). (Source 2)

• Randomized trial, Low certainty.
• Size: sodium sulfacetamide 10% and sulfur 5% cream with sunscreens (n = 75) and metronidazole 0.75% cream (n = 77) at 6 sites; randomised, investigator-blinded, parallel-group, no placebo arm.
• Who: People with rosacea.
• How long: 12 weeks.
• Result: Percentage reduction in inflammatory lesions 80% versus 72% (P = .04); subjects with improved erythema 69% vs 45% (P = .0007); success in global improvement at week 12 79% vs 59% (P = .01).
• Funding: not stated: the abstract carries no funding statement and the bibliographic record has none, and the trial compared two branded products.

Limit of this finding: This is the only randomised comparison with usable numbers for this product, and its design limits what it can show. It was randomised but only the investigators were blinded, there was no placebo group, and the comparator was an active drug - so a difference against another treatment is not the same as a demonstrated effect against no treatment. The same trial found no difference on investigator global severity and better tolerance in the metronidazole group.

After 12 weeks of treatment with sodium sulfacetamide 10% and sulfur 5% cream with sunscreens, there was a significantly greater percentage reduction (80%) in inflammatory lesions compared with metronidazole 0.75% cream (72%)(P = .04)

Rosacea is a chronic condition, so any benefit from topical treatment is control rather than cure. (Source 9)

• Systematic review, Moderate certainty.
• Size: not applicable; this is the review's one-line description of the condition, not one of its results.
• Who: People with rosacea.
• How long: not applicable.
• Result: No effect estimate for this statement; the review describes rosacea as a common chronic facial dermatosis and presents evidence for management rather than cure.
• Funding: not stated in the abstract.

Rosacea is a common chronic facial dermatosis. Classification of rosacea has evolved from subtyping to phenotyping.

What the evidence does not support

A systematic review with GRADE ratings set the sodium sulfacetamide with sulfur evidence aside as at unclear-to-high risk of bias, inadequately reported or too limited to grade. (Source 11)

• Systematic review, Very low certainty.
• Size: the sodium sulfacetamide with sulfur studies within a review of randomised rosacea trials.
• Who: People with rosacea.
• How long: not applicable.
• Result: No graded effect estimate was produced for sodium sulfacetamide with sulfur; its studies were handled in an appendix rather than in the graded recommendations.
• Funding: not stated in the abstract.

Studies evaluating permethrin, dapsone, sodium sulfacetamide with sulfur, pimecrolimus and some more unusual treatments (e.g. tranexamic acid, P‐3075 cream, SEI003 cream, praziquantel ointment, diclofenac sodium gel, incobotulinumtoxinA injections, kanuka honey) were at unclear‐to‐high risk of bias, inadequately reported or provided very limited data

A narrative review states plainly that no well-controlled trials compare sodium sulfacetamide with other topical therapies for perioral dermatitis. (Source 4)

• Expert review, not systematic, Very low certainty.
• Size: not applicable.
• Who: People with perioral dermatitis.
• How long: not applicable.
• Result: No effect estimate exists. The review notes the absence of controlled comparisons.
• Funding: not stated.

Unfortunately, however, there have been no well-controlled trials to compare the efficacy of sodium sulfacetamide to other topical therapies for this condition.

The authors concluded the pattern reflects a general predisposition to drug allergy rather than true cross-reactivity between sulfonamide-based drugs. (Source 5)

• Cohort study, Moderate certainty.
• Size: not restated in the conclusion.
• Who: Patients with a documented prior sulfonamide antibiotic hypersensitivity.
• How long: not restated in the conclusion.
• Result: No separate estimate; the conclusion interprets the odds ratios reported in the results.
• Funding: not stated in the abstract.

There is an association between hypersensitivity after the receipt of sulfonamide antibiotics and a subsequent allergic reaction after the receipt of a sulfonamide nonantibiotic, but this association appears to be due to a predisposition to allergic reactions rather than to cross-reactivity with sulfonamide-based drugs.

Where the evidence is mixed

In the same trial there was no difference between the two creams on investigator global severity, and tolerance was worse with the sulfacetamide-sulfur cream. (Source 2)

• Randomized trial, Low certainty.
• Size: n = 75 versus n = 77.
• Who: People with rosacea.
• How long: 12 weeks.
• Result: No significant difference in the percentage of subjects with improvement in investigator global severity. Overall tolerance good or excellent in 85% of the sulfacetamide-sulfur group versus 97% of the metronidazole group.
• Funding: not stated: the abstract carries no funding statement and the bibliographic record has none, and the trial compared two branded products.

Limit of this finding: This trial points two ways at once, and both directions are its own result. It favoured the sulfacetamide and sulfur cream on lesion counts, erythema and global improvement, and at the same time found the comparator cream better tolerated: overall tolerance was good or excellent in 97% of the metronidazole group against 85% of the sulfacetamide and sulfur group, and seven of its users tolerated it poorly. So the efficacy result is not a reason to read this as the gentler of the two creams. It was also randomised but only investigator-blinded, with an active comparator and no placebo arm, so neither arm's numbers measure anything against no treatment.

There was no significant difference between treatment groups in the percentage of subjects with improvement in investigator global severity.

The acne figure usually quoted for this combination - an 80.4% to 83% fall in inflammatory lesions over 12 weeks - comes from a narrative review citing studies without a placebo arm. (Source 3)

• Expert review, not systematic, Very low certainty.
• Size: not stated in the review.
• Who: People with acne vulgaris.
• How long: 12 weeks.
• Result: for 12 weeks decreases inflammatory acne lesions by 80.4% to 83%. No comparator or confidence interval is given.
• Funding: not stated.

Studies have demonstrated that twice-daily use of sodium sulfacetamide 10%– sulfur 5% for 12 weeks decreases inflammatory acne lesions by 80.4% to 83%.

The seborrhoeic dermatitis evidence is uncontrolled: response rates of 93%, 89% and 68% come from single studies with no comparison group. (Source 3)

• Expert review, not systematic, Very low certainty.
• Size: 71/76 cases in one study; 54/61 scalp and 30/44 glabrous skin patients in another.
• Who: People with seborrheic dermatitis.
• How long: not stated.
• Result: Improved or completely controlled in 93% (71/76) of cases with ointment and soap. Lotion effective in 89% (54/61) of patients with scalp involvement and 68% (30/44) of patients with glabrous skin involvement.
• Funding: not stated.

One study investigated the use of sodium sulfacetamide ointment and soap to treat seborrheic dermatitis and found that the condition was either improved or completely controlled in 93% (71/76) of cases.

The most recent clinical report for the emollient foam in acne is a case report series, not a controlled trial. (Source 12)

• Case series, Very low certainty.
• Size: a case report series of patients with acne vulgaris.
• Who: Patients with mild-to-moderate acne vulgaris, treated as monotherapy or with other topical acne products.
• How long: not stated in the abstract.
• Result: No comparator and no statistical analysis. The report is described by its author as a case report series, with patients treated as monotherapy or in combination with other topical acne products.
• Funding: The author discloses being a consultant, speaker and/or researcher for a long list of dermatology companies.

Limit of this finding: The percentages of dermatology visits in this article's opening - 11.3 percent for acne, and 6.2, 3.5 and 10 percent for eczematous dermatoses, psoriasis and skin cancer - are not this author's own data; the article attributes all of them to another paper, using superscript reference numbers that had been flattened into the running text in the version we first recorded, so that '2005.1' looked like a decimal. Those markers have been removed and none of those figures is used in anything we assert. What this article itself contributes is a case report series with no control group, which cannot show comparative efficacy.

This article provides an overview of the sodium sulfacetamide 10%-sulfur 5% emollient foam and reports the results of a case report series of patients with acne vulgaris treated with sodium sulfacetamide 10%-sulfur 5% emollient foam as monotherapy or in combination with other topical acne products.

Most people labelled allergic to sulfonamide antibiotics are not: nearly nine in ten had the allergy excluded on testing, and reactions on direct challenge were mild. (Source 13)

• Cohort study, Moderate certainty.
• Size: 125 patients assessed at two centres.
• Who: Adults carrying a sulfonamide antibiotic allergy label, inpatients and outpatients in Canada and Australia, excluding those with severe cutaneous adverse reactions.
• How long: single assessment with skin testing and direct oral challenge.
• Result: Allergy excluded in 112 of 125 patients (89.6%; 95% CI, 82.9%-94.3%). Direct oral challenge was negative in 100 of 104 patients (96.1%) with a risk score less than 3; the 4 who reacted (3.9%) had mild reactions. 9 of 21 patients (42.9%) with a score of 3 had positive testing.
• Funding: not stated in the passage.

Limit of this finding: The denominators behind these proportions are the cohort described in the companion passage from the same paper. One sentence of this passage is damaged in the published full text: it prints "(4 of 104 patients [3.9%]; ; among them" with a stray double semicolon, which looks like a bracketed phrase lost when the article was converted, so a few of the authors' own words are missing at that point. The figures either side of it are internally consistent (4 of 104 is 3.9%), and the study used the Fisher exact test with a two-sided P value below .05 counted as significant, but that one bracket should not be read as the authors' finished wording. The study also only skin-tested patients scoring 3 or more, so the comparison between risk bands is not like for like.

An allergy was excluded in 112 of 125 patients (89.6%; 95% CI, 82.9%-94.3%). DOC was negative in 100 of 104 patients (96.1%) with a score less than 3

The validation cohort was 125 adults carrying a sulfonamide-antibiotic allergy label at two hospitals, and it was weighted towards low risk: most scored 0 to 1 on the SULF-FAST tool (98 of 125 patients [78.4%]). (Source 14)

• Cohort study, Moderate certainty.
• Size: 125 patients assessed (96 at MUHC and 29 at AH)
• Who: Adults with a sulfonamide antibiotic allergy label at the McGill University Health Centre in Canada and Austin Health in Australia; median (IQR) age 60 (45-67) years, 91 of 125 (72.8%) female, 31 (24.8%) inpatients; the index reaction was a diffuse rash in 64 of 125 patients (51.2%), anaphylaxis in 5 of 125 (4.0%) and angioedema in 8 of 125 (6.4%)
• How long: single assessment.
• Result: Most patients had a SULF-FAST score of 0 to 1 (98 of 125 patients [78.4%]). The reaction occurred in childhood for 32 of 125 patients (25.6%) and was unknown for 17 of 125 (13.6%).
• Funding: not stated in the passage.

Limit of this finding: These are the denominators behind the testing results quoted beside them, so they belong on the record. Two things limit what the cohort shows. Almost four in five of these patients were already in the lowest risk band before any testing, so the high proportion cleared of their allergy label describes a mostly low-risk group rather than everyone who carries such a label. And the paper contains an arithmetic slip in this very paragraph: it prints "36 of 125 (38.8%)" for the number who were immunocompromised, but 36 out of 125 is 28.8%. Which of the two the authors meant cannot be worked out from the paper, so the share of immunocompromised patients should not be relied on. It does not affect the allergy results, whose own proportions all check out.

Among the 125 patients assessed (96 at MUHC and 29 at AH), the median (IQR) age was 60 (45-67) years, 91 of 125 (72.8%) were female

People with a past reaction to a sulfonamide antibiotic did react more often to a non-antibiotic sulfonamide, but they reacted to penicillin more often still, and less often to a non-antibiotic sulfonamide than people with a penicillin-allergy history - which is why the paper is titled 'Absence of cross-reactivity'. (Source 15)

• Cohort study, Moderate certainty.
• Size: 969 patients with an allergic reaction after a sulfonamide antibiotic and 19,257 without.
• Who: Patients in the General Practice Research Database in the United Kingdom who received a sulfonamide nonantibiotic.
• How long: within 30 days after the receipt of a sulfonamide nonantibiotic.
• Result: 96 of 969 (9.9 percent) with a prior reaction had an allergic reaction to a sulfonamide nonantibiotic, versus 315 of 19,257 (1.6 percent) without (adjusted odds ratio, 2.8; 95 percent confidence interval, 2.1 to 3.7). In the same people the risk after a penicillin was higher (adjusted odds ratio, 3.9; 95 percent confidence interval, 3.5 to 4.3). Reaction to a sulfonamide nonantibiotic was less likely than reaction to a penicillin in that group (adjusted odds ratio, 0.7; 95 percent confidence interval, 0.5 to 0.9) and less likely than in people with a penicillin-allergy history (adjusted odds ratio, 0.6; 95 percent confidence interval, 0.5 to 0.8).
• Funding: not stated in the abstract.

Limit of this finding: The version of this passage we first recorded stopped after the 2.8-fold figure and the penicillin comparison, which made it read as though a sulfonamide-antibiotic allergy specifically predisposes people to non-antibiotic sulfonamides. The two odds ratios below 1 that follow in the paper are what its title and conclusion rest on: the data point to a general tendency to drug allergy rather than cross-reactivity between sulfonamide antibiotics and sulfonamide non-antibiotics. This study is also about systemic non-antibiotic sulfonamides, not about topical sulfacetamide.

Furthermore, among those with a prior hypersensitivity reaction after the receipt of a sulfonamide antibiotic, the risk of an allergic reaction after the subsequent receipt of a sulfonamide nonantibiotic was lower than the risk of an allergic reaction after the subsequent receipt of a penicillin (adjusted odds ratio, 0.7; 95 percent confidence interval, 0.5 to 0.9).

Where the research disagrees

Whether sodium sulfacetamide with sulfur has demonstrated efficacy

• Wolf and Silapunt, narrative review in Cutis (2015), narrative review with no stated search method, citing uncontrolled studies some from the 1950s: The efficacy and safety of sodium sulfacetamide, used alone or in combination with sulfur, has been demonstrated in the treatment of rosacea, acne, seborrheic dermatitis, and perioral dermatitis. (Source 16)
• van Zuuren and colleagues, systematic review with GRADE in the British Journal of Dermatology (2019), systematic review of 152 randomised trials with GRADE certainty ratings: Studies evaluating permethrin, dapsone, sodium sulfacetamide with sulfur, pimecrolimus and some more unusual treatments (e.g. tranexamic acid, P‐3075 cream, SEI003 cream, praziquantel ointment, diclofenac sodium gel, incobotulinumtoxinA injections, kanuka honey) were at unclear‐to‐high risk of bias, inadequately reported or provided very limited data (Source 11)

How much

• Reference intake: Dosing is set by the prescriber. The label's position is to cleanse the skin thoroughly, then apply a thin layer to affected areas 1-3 times daily or as directed by a physician, starting with one application daily to limit dryness. (Source 17)
• Upper limit: No maximum daily amount is stated as a number. The label's ceiling is a frequency: a thin layer to affected areas 1-3 times daily or as directed by a physician, gradually increased from one application daily as needed. It is for external use only and is not to be used in people with kidney disease. (Source 17)
• Studied: The rosacea trial used sodium sulfacetamide 10% and sulfur 5% cream with sunscreens for 12 weeks against metronidazole 0.75% cream. (Source 2)
• Studied: The acne figures quoted in the review come from twice-daily use of sodium sulfacetamide 10% with sulfur 5% for 12 weeks. (Source 3)
• Studied: The labelled cream contains 100 mg of sodium sulfacetamide and 50 mg of sulfur per gram. (Source 18)

A common belief, and what the research shows

The belief: If you are allergic to sulfa drugs you can never use anything with sulfur or sulfacetamide in it, and if you are not, this cream is well proven.

What the research shows: Both halves need correcting. On allergy: the label does contraindicate it in known sulfonamide or sulfur hypersensitivity, and that should be respected - but most people carrying a sulfa allergy label do not have one. A two-country cohort reported "An allergy was excluded in 112 of 125 patients (89.6%; 95% CI, 82.9%-94.3%)." and a large UK database study concluded the link between sulfonamide-antibiotic reactions and later reactions to non-antibiotic sulfonamides "appears to be due to a predisposition to allergic reactions rather than to cross-reactivity with sulfonamide-based drugs." On proof: a graded systematic review of 152 rosacea trials found the sodium sulfacetamide with sulfur studies "were at unclear‐to‐high risk of bias, inadequately reported or provided very limited data".

Questions and answers

What is it?

It is a two-ingredient prescription skin treatment, sold as a cream, lotion, cleanser or foam. Sodium sulfacetamide is a sulfonamide antibacterial; sulfur is a keratolytic that loosens the top layer of skin. The 10%/5% cream contains 100 mg of sodium sulfacetamide and 50 mg of sulfur per gram. (Source 18)

What does it do in the body?

Sodium sulfacetamide is believed to stop bacteria growing by competing with para-aminobenzoic acid, which they need to make folate. Sulfur's keratolytic action is reported to come from reacting with the cysteine in skin cells, and the two together have been reported to inhibit the acne bacterium and so reduce inflammation. About 1% of applied sulfur is estimated to be absorbed; how much sodium sulfacetamide crosses intact skin has not been determined. (Source 1)

Is it good or bad for you?

It is modestly useful and poorly proven. The one randomised comparison in rosacea favoured it over metronidazole cream on lesion counts and erythema, but not on investigator global severity, and tolerance was worse (good or excellent in 85% versus 97%). A graded systematic review of randomised rosacea trials set its studies aside as too biased or too thin to grade. Harms are mostly local - dryness, redness, scaling, itching - with rare sulfonamide hypersensitivity. (Source 2)

How do you get more of it?

It is a prescription topical medicine, so it is not something you accumulate. The label's position is to cleanse the skin, then apply a thin layer to affected areas 1 to 3 times daily or as directed by a physician, starting at one application a day and increasing gradually to limit dryness. Frequency is the prescriber's decision. (Source 17)

If it is harmful, what reduces it?

You stop using it. The label says that if irritation develops the product should be discontinued and the irritation treated, and that people should be watched for local irritation or sensitisation during long-term therapy. There is no washout or antidote, and no withdrawal effect is described. (Source 8)

Why might someone be low in it or missing it?

This is a medicine rather than a nutrient, so the question is why someone might not be able to use it. The label bars it in anyone with known hypersensitivity to sulfonamides, to sulfur or to any other component, and in people with kidney disease. It is also for external use only, so it is not an option for anything other than skin. (Source 6)

Which whole foods contain it or feed it?

None. Neither ingredient comes from food in this form: sodium sulfacetamide is a manufactured sulfonamide with a defined chemical structure, and the sulfur here is elemental sulfur formulated into a cream base with preservatives and emulsifiers. Dietary sulfur-containing amino acids are a different thing entirely and are not a route to this medicine. (Source 18)

What happens if you do not have it?

Nothing happens from a bodily point of view - this is not a substance the body needs. The consequence of not using it is that the skin condition it was prescribed for goes untreated by this particular agent. For rosacea, which the evidence describes as a common chronic facial dermatosis, other treatments with stronger graded evidence exist, including topical brimonidine, azelaic acid and ivermectin. (Source 19)

How can you test for it?

There is no test for the drug itself; acne, rosacea and seborrhoeic dermatitis are diagnosed clinically. What can be tested is the sulfonamide allergy that would rule the product out, using skin testing and direct oral challenge - though the validated tools use the systemic antibiotic cotrimoxazole, not topical sulfacetamide, so they answer a related question rather than this one. (Source 20)

We searched: Europe PMC for sulfacetamide allergy and sulfonamide hypersensitivity testing; the DailyMed label; the Cutis review. No test for topical sulfacetamide or sulfur sensitivity with published performance data was found.

References

1. DailyMed / US FDA structured product label (Acella Pharmaceuticals). SODIUM SULFACETAMIDE 10% AND SULFUR 5% emollient cream - FDA prescribing information — label, CLINICAL PHARMACOLOGY section (LOINC 34090-1). 2026. Read the source
2. Cutis. Combination sodium sulfacetamide 10% and sulfur 5% cream with sunscreens versus metronidazole 0.75% cream for rosacea. 2005. PMID 16047874. Read the source
3. Cutis. The Use of Sodium Sulfacetamide in Dermatology. 2015. PMID 26367751. Read the source
4. Cutis. The Use of Sodium Sulfacetamide in Dermatology. 2015. PMID 26367751. Read the source
5. New England Journal of Medicine. Absence of cross-reactivity between sulfonamide antibiotics and sulfonamide nonantibiotics. 2003. PMID 14573734, DOI 10.1056/NEJMoa022963. Read the source
6. DailyMed / US FDA structured product label (Acella Pharmaceuticals). SODIUM SULFACETAMIDE 10% AND SULFUR 5% emollient cream - FDA prescribing information. 2026. Read the source
7. DailyMed / US FDA structured product label (Acella Pharmaceuticals). SODIUM SULFACETAMIDE 10% AND SULFUR 5% emollient cream - FDA prescribing information. 2026. Read the source
8. DailyMed / US FDA structured product label (Acella Pharmaceuticals). SODIUM SULFACETAMIDE 10% AND SULFUR 5% emollient cream - FDA prescribing information. 2026. Read the source
9. British Journal of Dermatology. Interventions for rosacea based on the phenotype approach: an updated systematic review including GRADE assessments — abstract, Background. 2019. PMID 30585305, DOI 10.1111/bjd.17590. Read the source
10. Cutis. The Use of Sodium Sulfacetamide in Dermatology. 2015. PMID 26367751. Read the source
11. British Journal of Dermatology. Interventions for rosacea based on the phenotype approach: an updated systematic review including GRADE assessments. 2019. PMID 30585305, DOI 10.1111/bjd.17590. Read the source
12. Journal of Clinical and Aesthetic Dermatology. The use of sodium sulfacetamide 10%-sulfur 5% emollient foam in the treatment of acne vulgaris. 2009. PMID 20729951. Read the source
13. JAMA Network Open. International Validation of the SULF-FAST Risk-Stratification Tool for Sulfonamide Antibiotic Allergy — full text, Results (outcomes paragraph). 2025. PMID 40622717, DOI 10.1001/jamanetworkopen.2025.19113. Read the source
14. JAMA Network Open. International Validation of the SULF-FAST Risk-Stratification Tool for Sulfonamide Antibiotic Allergy — full text, Results (cohort paragraph). 2025. PMID 40622717, DOI 10.1001/jamanetworkopen.2025.19113. Read the source
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