How to start tretinoin: strength, schedule, purging and what to expect

What tretinoin strength should you start with?

Start with 0.025%, or the lowest strength your prescriber offers, and move up only if your skin is calm. That reflects this review's reading of the evidence, not a rule any trial tested. For background on what the drug does, see our tretinoin explainer.

No head-to-head acne trial of strengths turned up in the research behind this piece. The AAD's 2024 acne guideline strongly recommends topical retinoids as a class, based on moderate-certainty evidence, but it does not rank strengths.

The skin-aging data are better but old. In a 6-month trial of 251 people, 0.05% tretinoin beat 0.01% and vehicle for fine wrinkling, mottled pigmentation and roughness, and results scaled with dose.

The only 0.025% versus 0.1% comparison we found was a 48-week trial of 90 people from 1995. Both beat vehicle, with no significant difference between them, and side effects were significantly more common at 0.1%. It is small and dated, so treat it as supportive, not definitive.

A Cochrane review of 30 trials found the same pattern: benefit and side effects both rise with dose. A 2022 review calls 0.05% the most common anti-aging strength and says 0.025% is generally considered effective with a reasonable safety profile.

Which strength is best for acne versus wrinkles?

For acne, the AAD calls topical retinoids the cornerstone of treatment. For wrinkles, tretinoin has the strongest track record, and the strength question is mostly about tolerance.

For acne, the AAD says retinoids are comedolytic and anti-inflammatory and help with maintenance. It also supports combining mechanisms, such as a retinoid with benzoyl peroxide. One catch: the AAD notes that standard tretinoin should not be applied together with benzoyl peroxide because of oxidation, while microsphere tretinoin, adapalene and tazarotene lack that restriction. Severe or scarring acne is a case for a dermatologist and possibly isotretinoin.

For wrinkles, a 2025 meta-analysis of 8 trials (1,361 patients) found tretinoin beat vehicle for both fine and coarse wrinkles. Adverse events were also more likely (odds ratio 3.14), and the trials are fairly old.

A systematic review still calls tretinoin the gold standard for photoaging while noting that poor tolerability often limits its use.

How do you apply tretinoin, and can you use it under the eyes?

Apply a thin layer to clean, completely dry skin at night. The label tells you to wash with mild soap, pat dry, and wait 20 to 30 minutes, because dry skin is less irritated.

Why night? Tretinoin is light-sensitive, so the AAD notes some formulations belong in the evening, and the label directs use once daily before bed. Your skin may also burn more easily in the sun while on it, so wear sunscreen and protective clothing.

How much? The patient leaflet says a half inch or less on a fingertip covers the whole face. If you can still see cream after rubbing it in, you used too much. The 'pea-sized' rule is popular shorthand, but it is not the label's wording.

• Dab it on the forehead, chin and both cheeks, then spread lightly.
• Keep it away from the corners of your nose and mouth, your eyes, and open wounds.
• The Renova label also says to avoid the ears and nostrils, and warns of severe redness, burning and peeling in those areas.

Under the eyes is a gap. We found no trial or guideline that addresses lower-eyelid use, and the label says to keep it away from the eyes. If you want to treat that area, ask your prescriber how to do it.

Why does tretinoin cause peeling, and what is a purge?

Peeling and dryness are the expected adjustment period, not proof the product is wrong for you. A review of retinoid tolerability explains that while skin shedding normalizes, cell cohesion is disturbed, then settles after a few weeks. In trials, irritation typically peaks in weeks 1 and 2.

The label says discomfort, peeling and blush usually subside within 2 to 4 weeks. Mayo Clinic says skin may be irritated during the first 3 weeks.

'Purging' is not a formal term in the sources, and no controlled study measuring it was identified. The label describes an apparent flare of inflammatory lesions in the early weeks, which it attributes to action on deep lesions you could not yet see. The leaflet says some people see new pimples around weeks 3 to 6 and should keep going. Treat that as the manufacturer's explanation, not a tested one.

• Ask about starting every other night; the label says doctors may advise this for sensitive skin.
• The review's checklist also suggests a gentle non-comedogenic moisturizer and 'short contact' (leave it on for 30 to 60 minutes, then wash off) for the first 2 to 4 weeks. These tactics are consensus-level, not proven in trials.
• Avoid medicated or abrasive soaps, astringents and high-alcohol products. Wind and cold add irritation.
• Use extreme caution on eczematous skin, where the label warns of severe irritation.

Contact your prescriber about pausing or reducing use if you get excessive redness, swelling, blistering or crusting. The label says to pause until skin recovers, then resume at a tolerable level. Rare true allergy and temporary pigment changes have been reported, so call your prescriber if reactions are severe.

When does tretinoin start working, and what if it doesn't?

Expect about 12 weeks for acne and 3 to 6 months for skin aging. Anything sooner is a bonus.

If nothing seems to happen, check consistency and amount first, since extra product does not speed results. For acne, the AAD supports combination therapy, including fixed-dose retinoid plus benzoyl peroxide, and recommends isotretinoin when standard treatment fails.

For aging, vehicle response can be high. One trial attributed that to the vehicle's own activity or regular sunscreen use, so daily SPF is not optional. Mottled pigmentation can improve earlier than wrinkles; in a 24-week trial, improvement began around week 8.

Can you use tretinoin with microneedling?

Pause it beforehand, and let the provider set the timing. We found no trial combining tretinoin with microneedling, so every instruction below is expert-level or consensus.

The AAD describes a 2 to 4 week pre-care routine that may include stopping retinoids for a few days. Cleveland Clinic says to stop exfoliants, including Retin-A, a week before.

A literature review on lasers and peels found no data showing you must stop at all, and suggested 24 hours. It also advised against starting tretinoin within 3 to 4 weeks of resurfacing, since new use causes dryness and exfoliation. The authors admit the evidence is thin and it does not cover microneedling.

We found no sourced guidance on when to restart afterward. Ask your provider, and do not assume.

Who can prescribe tretinoin, and where do you get it?

In the US, topical tretinoin requires a prescription, per Mayo Clinic. Beyond that, my sourcing is patchy, so verify locally.

• US: a doctor's prescription is needed. We could not source which other clinician types can prescribe or which telehealth services to trust, so ask your pharmacy or insurer.
• UK: one NHS formulary, Berkshire West, lists clindamycin/tretinoin gel (Treclin) as a first-choice acne product, not available over the counter, and flags Retin-A as discontinued. That is one local list, not national policy. Ask a GP or pharmacist about single-agent products.
• Canada: listed products include Stieva-A (0.01%, 0.025%, 0.05%), Retin-A cream 0.05%, Retin-A gel 0.025% and Retin-A Micro gel (0.04%, 0.1%). We did not confirm prescription status or online options.
• Australia: we found no source. Check scheduling and subsidy with the TGA, PBS or a pharmacist.

Cost in the US: a 2025 JAAD analysis listed 0.05% cream (45 g) at $42.90 with GoodRx and $53.58 through Mark Cuban Cost Plus. Another comparison says tretinoin is not available there, so availability may have changed.

Insurance rules vary by plan, and prior authorization requirements differ. We found no current source on coverage for wrinkles, which is plausibly treated as cosmetic, so ask your plan before you fill it.