Ciclopirox

What it is

A synthetic topical antifungal of the hydroxypyridone class, chemically 6-cyclohexyl-1-hydroxy-4-methyl-2(1H)-pyridone, molecular weight 207.27. It is unrelated to the azoles and to terbinafine. It is sold as an 8% nail lacquer (each gram contains 80 mg of ciclopirox in a film-forming solution of ethyl acetate and isopropyl alcohol), as a 0.77% cream, gel and suspension, and as a 1% shampoo. Nothing in the body makes it and no food contains it.

What the research says

It is an antifungal applied to skin, scalp or nails. The evidence differs sharply by site. On skin, a Cochrane review of placebo-controlled trials of athlete's foot found ciclopiroxolamine reduced treatment failure with a pooled risk ratio of 0.27. On the scalp, a Cochrane review found ciclopirox 1% reduced failed remission of seborrhoeic dermatitis (RR 0.79) with side-effect rates no different from placebo. On nails it works poorly: in the two US registration trials, complete cure at 48 weeks was 5.5% and 8.5% versus 0.9% and 0% with vehicle, and statistical significance for complete cure was reached in only one of the two trials. A 2020 Cochrane review rated the complete-cure evidence for ciclopirox 8% lacquer as low quality and noted it may increase local adverse events. Systemic absorption is under 5% of the applied dose, which is why serious systemic harms and drug interactions are not a feature.

Evidence grade: Limited evidence.

How it works

Drug class: Hydroxypyridone topical antifungal

Ciclopirox does not attack fungal sterol synthesis the way azoles and terbinafine do. Laboratory work suggests it grabs hold of polyvalent metal ions, especially iron (Fe3+) and aluminium (Al3+), which disables metal-dependent fungal enzymes - including those that clear toxic peroxides inside the fungal cell - and disrupts energy production and transport. The label is explicit that the clinical significance of this mechanism is not known. It is also reported to have activity against some bacteria and anti-inflammatory properties. (Source 1)

What it is used for

• Approved only as part of a programme that includes monthly professional removal of unattached infected nail. In the two US registration trials, complete cure at 48 weeks was 5.5% versus 0.9% and 8.5% versus 0%, and complete cure reached statistical significance in only one of the two. A 2020 Cochrane review of 56 studies rated ciclopirox 8% lacquer as low-quality evidence for complete cure (RR 9.29, 95% CI 1.72 to 50.14) and concluded that complete cure rates with topical treatments are relatively low. An earlier Cochrane review of foot infections stated plainly that topical ciclopiroxolamine has poor cure rates for nails. Evidence: limited. (Source 2)
• For fungal infection of the skin of the foot, a Cochrane review of 67 randomised trials found placebo-controlled trials of ciclopiroxolamine gave a pooled risk ratio of treatment failure of 0.27 (95% CI 0.11 to 0.66), comparable to the allylamines and azoles. The same review found allylamines cured slightly more skin infections than azoles. Evidence: established. (Source 3)
• A 2015 Cochrane review of 51 trials and 9052 participants included 11 ciclopirox trials (3029 participants) and found ciclopirox 1% reduced failed remission at four weeks (RR 0.79, 95% CI 0.67 to 0.94, moderate-quality evidence) with side-effect rates similar to placebo, and performed similarly to ketoconazole. The review flagged that 24 of the included trials had some form of conflict of interest and that almost no trial looked beyond four weeks. Evidence: limited. (Source 4)
• Widely done in practice but explicitly not recommended on the US 8% lacquer label, which states no study has been done to see whether ciclopirox reduces the effectiveness of systemic antifungals. The only sizeable dataset is a retrospective multicentre record review of 408 Spanish patients in which response was unrelated to whether the lacquer was started before, with or after the oral drug; there is no randomised comparison. Evidence: unknown. (Source 5)
• Moderate-quality Cochrane evidence from two studies (490 participants) found this water-soluble formulation more likely than ciclopirox 8% lacquer or amorolfine 5% to achieve complete cure (RR 2.43, 95% CI 1.32 to 4.48), but with probably little or no difference in mycological cure (RR 1.08, 95% CI 0.85 to 1.37). Evidence: limited. (Source 6)

Interactions

• Oral (systemic) antifungal drugs for onychomycosis, such as terbinafine, itraconazole and fluconazole (label): Nobody has tested whether the lacquer blunts an oral antifungal, so the US label advises against using them together for onychomycosis even though the combination is common in practice. A 408-patient retrospective record review found response did not depend on the order of starting them, but that is not a randomised comparison. (Source 5)
• Drugs cleared by cytochrome P450 enzymes (the route for grapefruit, St John's wort and many azole interactions) (pharmacokinetic study): Ciclopirox is cleared mainly by glucuronidation rather than by cytochrome P450, so the P450-mediated interactions that dog the azole antifungals - and the P450 effects of grapefruit juice or St John's wort - are not expected with it. (Source 7)
• Alcohol (drinking alcohol) (pharmacokinetic study): No interaction with drinking alcohol is documented, and the pharmacokinetic reason is that under 5% of an applied dose reaches the body. Separately, the lacquer film itself is removed with alcohol as part of weekly nail care, and the solution contains isopropyl alcohol and ethyl acetate as solvents, which makes it flammable. (Source 8)
• Iron, zinc, calcium, magnesium and other mineral supplements (theoretical): Theoretical only. Ciclopirox works by chelating polyvalent metal ions such as Fe3+ and Al3+ inside the fungal cell, which has prompted speculation about metal supplements, but no human study of such an interaction was found and the label states the clinical significance of the chelation mechanism itself is unknown. (Source 1)

Stopping it

• There is no withdrawal syndrome and no taper. The practical question is relapse, and the label answers it only partly: post-treatment assessments were scheduled only for the people who had reached a complete cure, and of those assessed, 3 of 4 in one trial and 4 of 8 in the other were still completely cured 12 weeks later. No overall relapse rate can be calculated from this. (Source 9)
• Systemic traces clear quickly after stopping: a month after the end of treatment, ciclopirox was undetectable in serum and urine. (Source 8)
• The label's only instruction to stop is for a reaction: if sensitivity or chemical irritation develops, treatment should be stopped and the reaction treated. (Source 10)
• Stopping early is the main reason topical nail treatment fails: a Cochrane review notes the drug has to be applied daily for prolonged periods, at least a year, for any effect on nails. (Source 3)

What goes wrong

The same review found ciclopirox 8% lacquer may increase adverse events, though the confidence interval includes no difference. (Source 6)

• Systematic review, Low certainty.
• Size: 2 studies for the ciclopirox 8% lacquer comparison.
• Who: people with toenail onychomycosis.
• How long: 36 to 48 weeks of treatment.
• Result: adverse events RR 1.61 (95% CI 0.89 to 2.92), low-quality evidence; commonly application reactions, rashes and nail alteration such as colour or shape change.
• Funding: not stated in the abstract; Cochrane review.

Ciclopirox lacquer may lead to increased adverse events, commonly application reactions, rashes, and nail alteration (e.g. colour, shape). However, the 95% CI indicates that ciclopirox lacquer may actually make little or no difference (RR 1.61, 95% CI 0.89 to 2.92; low-quality evidence).

In the vehicle-controlled nail lacquer trials, skin and nail-fold reactions were more common with ciclopirox than with vehicle. (Source 11)

• Randomized trial, Moderate certainty.
• Size: 327 ciclopirox and 328 vehicle patients in the US vehicle-controlled trials.
• Who: US adults treated for toenail onychomycosis.
• How long: 48 weeks.
• Result: causally related treatment-emergent adverse events 9% (30/327) ciclopirox vs 7% (23/328) vehicle; skin and appendages 8% (27/327) vs 4% (14/328); periungual erythema and erythema of the proximal nail fold 5% (16/327) vs 1% (3/328); nail disorders 2% vs 2%; application site reactions or burning 1% in both.
• Funding: manufacturer registration trials reported in the FDA label.

periungual erythema and erythema of the proximal nail fold were reported more frequently in patients treated with ciclopirox topical solution, 8% (Nail Lacquer), (5% [16/327]) than in patients treated with vehicle (1% [3/328]).

A 21-day semi-occluded irritancy study produced mild transient erythema in nearly half of subjects, and a maximised photosensitisation study produced localised allergic contact reactions in four subjects. (Source 12)

• Randomized trial, Low certainty.
• Size: not stated for the irritancy study; 4 subjects with reactions in the photosensitisation study.
• Who: human volunteers under semi-occlusion, and a maximised photosensitisation test design including occluded sodium lauryl sulfate.
• How long: 21 days for the irritancy study.
• Result: mild reactions in 46% with ciclopirox solution, 32% with vehicle, 2% with negative control, all mild transient erythema; no evidence of allergic contact sensitisation in the irritancy study; no photoallergic reactions, but localised allergic contact reactions in four subjects.
• Funding: manufacturer studies reported in the FDA label.

Mild reactions were seen in 46% of patients with the ciclopirox topical solution, 8% (Nail Lacquer), 32% with the vehicle and 2% with the negative control, but all were reactions of mild transient erythema.

Allergic contact dermatitis to ciclopirox olamine has been confirmed by patch testing, but is rarely reported. (Source 13)

• Case report, Very low certainty.
• Size: 1 patient.
• Who: a 50-year-old man with interdigital tinea pedis.
• How long: not stated.
• Result: dermatitis spread from the toes to the lower shins; patch tests strongly positive to ciclopirox olamine 1% in petrolatum.
• Funding: not stated.

Patch tests were strongly positive to ciclopirox olamine 1% pet. Sensitization to this topical antifungal agent has rarely been reported in the literature.

Applying ciclopirox hydroxypropyl chitosan lacquer over a breathable cosmetic nail polish reduced drug flux through the nail when applied once daily, though antifungal activity of the permeate was retained. (Source 14)

• Lab study in cells, Very low certainty.
• Size: not applicable; bovine hoof membranes.
• Who: not human; in vitro permeation model with susceptibility testing of the permeate.
• How long: not stated.
• Result: with cosmetic polish underneath, once-daily drug transungual flux tended to decrease while antifungal activity was maintained; twice-daily application restored the permeation profile of once-daily application on bare nail.
• Funding: not stated in the abstract; the study concerns a specific branded formulation and reads as manufacturer-aligned.

After CPX-HPCH NL application once a day, the drug transungual flux in the presence of cosmetic product tended to decrease while maintaining the antifungal activity.

Post-treatment follow-up in the registration trials was only scheduled for the few people who had reached a complete cure at 48 weeks, and in the trial arm with most cures fewer than half of those assessed were still completely cured 12 weeks later. (Source 9)

• Randomized trial, Low certainty.
• Size: 6 and 10 complete cures in the two active arms; 4 and 8 of those had week 12 post-treatment assessments.
• Who: US adults who had achieved complete cure of the target toenail at week 48.
• How long: 12 weeks after the end of 48 weeks of treatment.
• Result: complete cures at week 48: 6 of 112 (study 312 active) and 10 of 119 (study 313 active). Of those, 2 and 2 respectively had no week 12 assessment, leaving 4 and 8 assessed; complete cure persisted in 3 of 4 and 4 of 8. Because post-treatment assessments were scheduled only for people already cured, no relapse rate for the whole trial population can be calculated.
• Funding: manufacturer registration trials reported in the FDA label.

Limit of this finding: The label's own table is misprinted here. The row 'Patients Missing All Week 12 Assessments' is published with only three numbers, and a fourth number (2) sits on the heading row above it, so read straight off the page the figures line up against the wrong rows. The arithmetic of the surrounding rows shows that row is 2, 0, 2, 0. We have used the corrected figures and have not quoted the table itself. What a reader should take from this section is that follow-up after treatment covered only the small minority who were already cured, so it says nothing about how the rest of the trial population fared.

Note that post-treatment efficacy assessments were scheduled only for patients who achieved a complete cure.

What the evidence supports

A Cochrane review found ciclopirox 8% lacquer may be more effective than vehicle at achieving complete cure of toenail onychomycosis, but rated that evidence low quality. (Source 6)

• Systematic review, Low certainty.
• Size: 2 studies, 460 participants for the ciclopirox 8% lacquer comparison, within a review of 56 studies and 12,501 participants.
• Who: people with mainly mild-to-moderate toenail onychomycosis without matrix involvement, mean ages 27 to 68.
• How long: treatment 36 or 48 weeks, outcomes at 40 to 52 weeks.
• Result: complete cure RR 9.29 (95% CI 1.72 to 50.14), low-quality evidence; mycological cure RR 3.15 (1.93 to 5.12), moderate-quality evidence.
• Funding: not stated in the abstract; Cochrane review. Only 3 of the 56 included studies were at low risk of bias across all domains, and the commonest high-risk domain was performance bias.

Based on two studies (460 participants), compared with vehicle, ciclopirox 8% lacquer may be more effective in achieving complete cure (risk ratio (RR) 9.29, 95% confidence interval (CI) 1.72 to 50.14; low-quality evidence) and is probably more effective in achieving mycological cure (RR 3.15, 95% CI 1.93 to 5.12; moderate-quality evidence).

The absolute complete-cure numbers from those registration trials are small in both arms. (Source 2)

• Randomized trial, Moderate certainty.
• Size: 219 and 235 participants in the intent-to-treat complete cure analyses.
• Who: US adults with mild to moderate great-toenail onychomycosis.
• How long: 48 weeks plus last observation carried forward.
• Result: Complete cure 6/110 (5.5%) vs vehicle 1/109 (0.9%) in study 312; 10/118 (8.5%) vs vehicle 0/117 (0%) in study 313.
• Funding: manufacturer registration trials reported in the FDA label; funding not separately stated.

Complete Cure* 6/110 (5.5%) 1/109 (0.9%) 10/118 (8.5%) 0/117 (0%)

For fungal infection of the skin of the foot, the same Cochrane review found ciclopiroxolamine reduced treatment failure to roughly a quarter of placebo. (Source 3)

• Systematic review, Moderate certainty.
• Size: 67 trials met inclusion criteria out of 144 identified papers.
• Who: people with mycologically diagnosed fungal infections of the skin of the foot.
• How long: varied by trial.
• Result: pooled risk ratio of treatment failure for ciclopiroxolamine 0.27 (95% CI 0.11 to 0.66); allylamines 0.33 (0.24 to 0.44); azoles 0.30 (0.20 to 0.45); allylamines favoured over azoles RR 0.63 (0.42 to 0.94)
• Funding: not stated in the abstract; Cochrane review.

Placebo-controlled trials yielded the following pooled risk ratios (RR) of treatment failure for skin infections: allylamines RR 0.33 (95% CI 0.24 to 0.44); azoles RR 0.30 (95% CI 0.20 to 0.45); ciclopiroxolamine RR 0.27 (95% CI 0.11 to 0.66); tolnaftate RR 0.19 (95% CI 0.08 to 0.44); butenafine RR 0.33 (95% CI 0.24 to 0.45); undecanoates RR 0.29 (95% CI 0.12 - 0.70).

For seborrhoeic dermatitis, a Cochrane review found ciclopirox 1% reduced failed remission at four weeks with side-effect rates similar to placebo. (Source 4)

• Systematic review, Moderate certainty.
• Size: 11 ciclopirox trials with 3029 participants, within a review of 51 studies and 9052 participants.
• Who: adolescents and adults with seborrhoeic dermatitis of the face or scalp.
• How long: 45 of 51 trials assessed outcomes at five weeks or less.
• Result: failed remission RR 0.79 (95% CI 0.67 to 0.94) across 8 studies, moderate-quality evidence; side effects RR 0.9 (0.72 to 1.11) across 4 studies, moderate-quality evidence.
• Funding: the review authors judged that 24 of the included trials had some form of conflict of interest, such as pharmaceutical company funding.

Ciclopirox 1% led to a lower failed remission rate than placebo at four weeks of follow-up (RR 0.79, 95% CI 0.67 to 0.94, eight studies, moderate-quality evidence) with similar rates of side effects (RR 0.9, 95% CI 0.72 to 1.11, four studies, moderate-quality evidence).

In a randomised double-blind trial of scalp seborrhoeic dermatitis, ciclopirox olamine 1.5% shampoo beat placebo and was at least as good as 2% ketoconazole on area affected. (Source 15)

• Randomized trial, Low certainty.
• Size: 350 patients (150 ciclopirox olamine, 150 ketoconazole, 50 placebo)
• Who: people with scalp seborrhoeic dermatitis.
• How long: 4-week treatment period, with a 2-week run-in and 2-week run-out.
• Result: mean reduction in area affected 48.2 cm2 with ciclopirox olamine, 41.4 cm2 with ketoconazole, 20.0 cm2 with placebo; patients rated ciclopirox olamine better than placebo (p<0.001) and than ketoconazole (p<0.05)
• Funding: not stated in the abstract; the small placebo arm (50 versus 150 per active arm) is an imbalanced design typical of manufacturer-sponsored shampoo trials.

The mean reduction from baseline to end of treatment was 48.2 cm(2) with CPO, 41.4 cm(2) with ketoconazole and 20.0 cm(2) with placebo.

Systemic exposure from the nail lacquer is minimal, which is why systemic harms and drug interactions are not a major concern. (Source 8)

• Blood level study, Low certainty.
• Size: 5 patients for the six-month absorption study; 66 randomly selected patients on active treatment in the vehicle-controlled trials.
• Who: patients with dermatophytic onychomycosis applying the lacquer to all 20 digits and 5 mm of adjacent skin once daily.
• How long: 6 months, with sampling at 2 weeks and 1, 2, 4 and 6 months plus 4 weeks post-treatment.
• Result: serum levels 12-80 ng/mL; mean absorption under 5% of the applied dose based on urinary data; 24 of 66 patients in the controlled trials had detectable serum levels (10.0-24.6 ng/mL), but 11 of those 24 were also using a ciclopirox olamine cream.
• Funding: manufacturer studies reported in the FDA label.

Based on urinary data, mean absorption of ciclopirox from the dosage form was <5% of the applied dose.

What the evidence does not support

The same Cochrane review concluded that although topical treatments work, the absolute chance of a complete cure is low. (Source 6)

• Systematic review, Moderate certainty.
• Size: 56 studies, 12,501 participants.
• Who: people with toenail onychomycosis.
• How long: mostly 48 to 52 weeks.
• Result: no single figure is given for the class; the authors state complete cure rates with topical treatments are relatively low, and downgraded evidence for heterogeneity, lack of blinding and small sample sizes.
• Funding: not stated in the abstract; Cochrane review.

Although evidence supports topical treatments, complete cure rates with topical treatments are relatively low.

An earlier Cochrane review of topical treatments for foot infections stated that topical ciclopiroxolamine has poor cure rates for nail infections and that amorolfine might be substantially more effective. (Source 3)

• Systematic review, Low certainty.
• Size: 6 trials of nail infections within a review of 67 included trials.
• Who: people with mycologically diagnosed fungal infections of the skin and nails of the foot.
• How long: topical nail treatment needed daily for at least one year.
• Result: no pooled figure for nails; the authors state ciclopiroxolamine has poor cure rates and that further research is required.
• Funding: not stated in the abstract; Cochrane review.

The 6 trials of nail infections provided evidence that topical ciclopiroxolamine has poor cure rates and that amorolfine might be substantially more effective but more research is required.

In an ex vivo nail model, 8% ciclopirox barely affected established dermatophyte growth and did not eliminate the fungus from the nail material at all. (Source 16)

• Lab study in cells, Low certainty.
• Size: not stated; one ex vivo study in ovine hoof material.
• Who: not human; new and established Trichophyton rubrum and Trichophyton mentagrophytes infections in ovine hoof.
• How long: 10 days of treatment.
• Result: growth of T. rubrum and T. mentagrophytes in the established infection model was very minimally affected; elimination of the molds was not achieved in either the new or established models.
• Funding: manufacturer study reported in the FDA label.

After 10 days of treatment the growth of T. rubrum and T. mentagrophytes in the established infection model was very minimally affected. Elimination of the molds from hoof material was not achieved in either the new or established infection models.

Where the evidence is mixed

In the two US registration trials, complete cure of the target great toenail at 48 weeks was 5.5% and 8.5% with ciclopirox 8% lacquer versus 0.9% and 0% with vehicle, and complete cure reached statistical significance in only one of the two trials. (Source 2)

• Randomized trial, Moderate certainty.
• Size: two double-blind vehicle-controlled trials; 219 and 235 participants analysed for complete cure (223 and 237 randomised)
• Who: US adults with onychomycosis of a great toenail without lunula involvement, 20-65% of the target nail plate involved, positive microscopy and dermatophyte culture.
• How long: 48 weeks of daily application, with monthly professional removal of unattached infected nail.
• Result: complete cure 6/110 (5.5%) vs 1/109 (0.9%) in study 312 and 10/118 (8.5%) vs 0/117 (0%) in study 313; almost clear 6.5% vs 0.9% and 12% vs 0.9%; negative mycology alone 29% vs 11% and 36% vs 9%.
• Funding: not stated; these are the manufacturer's registration trials as reported in the FDA label.

Statistical significance was demonstrated in one of two studies for the endpoint “complete cure” (clear nail and negative mycology), and in two studies for the endpoint “almost clear” (≤ 10% nail involvement and negative mycology) at the end of study.

Ciclopirox was no better than ketoconazole for seborrhoeic dermatitis, and the evidence base for the whole class is conflicted and short-term. (Source 4)

• Systematic review, Low certainty.
• Size: 3 studies for the ketoconazole versus ciclopirox comparison.
• Who: adolescents and adults with seborrhoeic dermatitis.
• How long: four weeks in most trials; only 6 of 51 trials looked at longer time frames.
• Result: remission failure RR 1.09 (95% CI 0.95 to 1.26), low-quality evidence; no study assessed quality of life.
• Funding: 24 of 51 included trials judged to have some form of conflict of interest.

We believe that 24 trials had some form of conflict of interest, such as funding by pharmaceutical companies.

In a retrospective multicentre record review of people given the hydroxypropyl chitosan lacquer plus an oral antifungal, response did not depend on which drug was started first or which oral agent was used. (Source 17)

• Cohort study, Very low certainty.
• Size: 408 patients at three Spanish tertiary hospitals.
• Who: patients diagnosed with onychomycosis receiving combined ciclopirox 8% HPCH and an oral antifungal; mean age 51.1 years, 54.4% female.
• How long: retrospective record review; duration of treatment not stated.
• Result: positive response 15.7%, presumed positive 59.8%, unrelated to treatment synchronicity or oral agent; erythema 5.6%, diarrhoea 4.9%, fever 4.2% were the most frequently recorded potential adverse events.
• Funding: not stated in the abstract; the study used a proprietary natural-language-processing platform and concerns a specific branded formulation.

The response to treatment (positive response 15.7%, presumed positive 59.8%) was unrelated to treatment synchronicity or type of antifungal agent.

Where the research disagrees

Whether the newer hydroxypropyl chitosan formulation of ciclopirox 8% is meaningfully better than the original lacquer

• Piraccini and colleagues, in a 2020 review of the product in Dermatology and Therapy, narrative review with no stated search method; the comparative-efficacy and tolerability statements are these authors’ summary of other people’s studies, not results they measured, and the review does not state whether it was industry-sponsored: In clinical studies in patients with mild-to-moderate onychomycosis, ciclopirox 8% HPCH was found to be more effective than the commercial water-insoluble ciclopirox 8% and amorolfine 5% lacquers, as indicated by higher complete cure, response and mycological cure rates at 48 weeks after treatment initiation. (Source 18)
• The 2020 Cochrane review, systematic review with GRADE ratings; agrees on complete cure but finds no difference on the microbiological outcome: Moderate-quality evidence from two studies (490 participants) indicates that P-3051 (ciclopirox 8% hydrolacquer) is probably more effective than the comparators ciclopirox 8% lacquer or amorolfine 5% in achieving complete cure (RR 2.43, 95% CI 1.32 to 4.48), but there is probably little or no difference between the treatments in achieving mycological cure (RR 1.08, 95% CI 0.85 to 1.37). (Source 6)

Whether ciclopirox nail lacquer should be described as effective for onychomycosis at all

• The authors of the registration-trial report (Journal of the American Academy of Dermatology, 2000), report of two vehicle-controlled registration trials plus non-US and open-label studies, written by investigators involved with the product: Studies conducted worldwide demonstrate the efficacy of ciclopirox nail lacquer for the treatment of finger and toe onychomycosis. (Source 19)
• The Cochrane review of topical treatments for foot infections (2007), systematic review of 67 randomised trials: The 6 trials of nail infections provided evidence that topical ciclopiroxolamine has poor cure rates and that amorolfine might be substantially more effective but more research is required. (Source 3)

How much

• Reference intake: There is no reference intake for a drug and ciclopirox is not a nutrient. Dosing is set by the prescriber. As a position, the FDA label of 17 November 2025 for the 8% nail lacquer states it should be applied once daily to all affected nails, over the whole nail plate, as part of a programme that also includes monthly professional removal of unattached infected nail. (Source 20)
• Upper limit: No numerical upper limit is set for a topical antifungal. As a position, the same label states that safety and efficacy of daily use beyond 48 weeks have not been established. The 1% shampoo label instead limits treatment to twice a week for four weeks. (Source 5)
• Studied: The two US registration trials applied ciclopirox topical solution 8% (nail lacquer) daily for 48 weeks. (Source 2)
• Studied: The scalp seborrhoeic dermatitis trial compared 1.5% ciclopirox olamine shampoo with 2.0% ketoconazole shampoo and placebo over a 4-week treatment period. (Source 15)
• Studied: The US 1% shampoo label directs roughly 1 teaspoon (5 mL) to the scalp, lathered and left for 3 minutes, twice per week for 4 weeks with at least 3 days between applications. (Source 21)

A common belief, and what the research shows

The belief: Painting on a prescription antifungal nail lacquer will clear a fungal nail.

What the research shows: On the label's own numbers, "Complete Cure* 6/110 (5.5%) 1/109 (0.9%) 10/118 (8.5%) 0/117 (0%)" - that is, roughly one person in twelve to one in eighteen ends up with a clear nail and negative fungal tests after 48 weeks of daily application, against about one in a hundred on vehicle. Cochrane's verdict on the whole topical class is that "Although evidence supports topical treatments, complete cure rates with topical treatments are relatively low." Mycological cure (killing the fungus without the nail looking normal) is much commoner than complete cure, which is why reported success rates vary so widely. The same drug is considerably more effective on skin than on nails.

Questions and answers

What is it?

Ciclopirox is a laboratory-made antifungal of the hydroxypyridone class, not related to the azoles or to terbinafine. It comes as an 8% nail lacquer that dries to a film, as a 0.77% cream, gel or suspension for skin, and as a 1% shampoo for the scalp. In the nail lacquer, each gram contains 80 mg of ciclopirox dissolved in ethyl acetate and isopropyl alcohol, which evaporate after it is painted on. (Source 22)

What does it do in the body?

It kills or stops the growth of fungi on the surface it is applied to. Laboratory work suggests it does this by binding metal ions such as iron inside the fungal cell, which shuts down metal-dependent enzymes the fungus needs - including the ones that mop up toxic peroxides - rather than by blocking sterol synthesis as other antifungals do. The label states the clinical significance of this mechanism is not known. (Source 1)

Is it good or bad for you?

It is a treatment rather than something good or bad in itself, and it is far more useful on skin than on nails. For athlete's foot the pooled risk ratio of treatment failure versus placebo was 0.27; for scalp seborrhoeic dermatitis it reduced failed remission with side effects no different from placebo. For nails, Cochrane rated the complete-cure evidence low quality and concluded complete cure rates with topical treatments are relatively low. Harms are local: periungual redness in about 5% versus 1% with vehicle, and rare confirmed contact allergy. (Source 6)

How do you get more of it?

This question does not apply as it would to a nutrient. Ciclopirox is a prescription topical medicine with no dietary or supplement source. How much is used is set by the prescriber; for the nail lacquer the label describes once-daily application over the whole nail plate, alongside weekly filing by the person and monthly removal of unattached infected nail by a professional. (Source 20)

If it is harmful, what reduces it?

If it causes a reaction, the label's instruction is to stop it and treat the reaction. Nothing special is needed to clear it from the body: under 5% of an applied dose is absorbed at all, and a month after treatment ends it is undetectable in blood and urine. The lacquer film itself is removed from the nail with alcohol during weekly nail care. (Source 10)

Why might someone be low in it or missing it?

There is no deficiency of ciclopirox - the body neither makes nor needs it. The equivalent question is why it might not work, and the label's own boundaries answer it: it was only ever shown to work in immunocompetent people with mild to moderate nail infection that has not reached the nail matrix (the lunula). People who were immunosuppressed, HIV positive, transplant recipients, insulin-dependent diabetics, or who had severe moccasin-type tinea pedis were excluded from the trials altogether. (Source 5)

Which whole foods contain it or feed it?

None. Ciclopirox is a synthetic molecule; no whole food contains it and no food feeds it. Nothing in the diet raises or lowers the amount on a nail or on the skin. (Source 22)

What happens if you do not have it?

Not taking it has no consequence of its own; it is one of several antifungals, and for skin infections the allylamines cured slightly more infections than the azoles in pooled trials. What is left untreated is the infection, which Cochrane describes as capable of causing pain, discomfort and disfigurement of the nail. (Source 6)

How can you test for it?

There is no test for ciclopirox levels in ordinary use, and blood levels are not monitored because so little is absorbed. What is worth testing is whether a fungus is there at all: the trials that support the drug all required laboratory confirmation by culture, direct microscopy or nail histology before treatment, because discoloured or thickened nails often have another cause. The shampoo label adds that if seborrhoeic dermatitis has not improved after four weeks, the diagnosis should be reviewed. (Source 6)

References

1. DailyMed (US National Library of Medicine), label of Chartwell RX, LLC. Ciclopirox Topical Solution, USP 8% (Nail Lacquer) - FDA label, DailyMed version published 17 Nov 2025 - CLINICAL PHARMACOLOGY - Mechanism of Action section. 2025. Read the source
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