How long does it take to see results?

Nobody publishes a day-by-day curve, so the honest answer is the week the trial chose to measure. It ranges from about 1.5 weeks to 52 weeks depending on the treatment, and the middle of the range is week 12.

Does that mean nothing happens before then?

No. It means nobody counted before then. Something may well be improving earlier; the trial simply did not measure it, so there is no number to quote.

Why do so many stop at week 12?

Twelve weeks is the conventional length for a topical dermatology trial, long enough for a skin cycle to turn over several times and short enough to run. It is a convention, not a biological deadline.

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How long before anyone even measured?

Pick a treatment. See the week the trial chose to measure — the earliest point anyone counted.

Choose a treatment

Measured at

52 weeks

Day one52 weeks

Complete cure at week 52

17.8% on the treatment, 3.3% on Vehicle.

Trial detail

The trial: Two randomised, vehicle-controlled phase 3 trials; Cochrane CD012093.pub2.

Every dated readout, longest first

52 weeksEfinaconazole 10% solution (Jublia)
24 weeksMinoxidil 5% topical foam (Rogaine)
24 weeksEflornithine 13.9% cream (Vaniqa)
13 weeksTopical salicylic acid for warts
12 weeksBenzoyl peroxide 2.5% leave-on gel
12 weeksAdapalene 0.1% gel (Differin)
12 weeksAdapalene 0.1% + benzoyl peroxide 2.5% fixed combination (Epiduo)
12 weeksThiamidol (Eucerin Anti-Pigment / Radiant Tone)
12 weeksUrea 10% cream or lotion
6 weeksTerbinafine 1% cream or spray
6 weeksButenafine 1% cream
4.5 weeksKetoconazole 2% shampoo
4 weeksClotrimazole 1% cream
4 weeksSelenium sulfide 1% shampoo
4 weeksCiclopirox shampoo (Loprox 1% / Stieprox 1.5%)
4 weeksPyrithione zinc 1% shampoo
2 weeksMiconazole nitrate 0.25% in zinc oxide 15% / white petrolatum (Vusion)
1.5 weeksDimeticone head lice treatment

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Sources & limitsWhere the answer comes from and what it cannot prove

What the week actually is

It is the timepoint the trial defined as its result — the moment participants were assessed and the published number was produced. It is the earliest point at which anyone can say what the treatment did.

A treatment measured at week 24 is not slower than one measured at week 4. It means its trial ran longer, usually because the thing it treats changes slowly — a nail, a hair cycle, a pigment.

Why this is the honest answer

"Results in two weeks" is a marketing sentence, not a measurement. The measured week is checkable: it is written into the trial record, and every row here links to that record.

For the numbers each trial produced at that point, including the arm it was compared against, see the placebo margin check.

What this can’t tell you

This is when a trial measured, not when you personally will notice anything. Individual response varies, doses vary, and skin conditions come and go on their own. Treat the week as the earliest fair moment to judge, not a promise.