Retinoids explained: retinol, adapalene and tretinoin, and how to start without irritation
If dermatologists agree on one active ingredient for both acne and sun-related skin aging, it is a retinoid. The family includes the gentle retinol of cosmetic serums, an acne gel sold over the counter in the US, and the prescription creams that started it all. They work, and they irritate. The difference between people who give up after two weeks and people who use them for years is mostly in how they start.
- Retinoids are vitamin A derivatives. Strength runs roughly: retinyl esters < retinol < retinal < adapalene / tretinoin.
- In the US, adapalene 0.1% has been sold over the counter for acne since 2016, for ages 12 and up; tretinoin needs a prescription.
- The American Academy of Dermatology advises starting every other night, in the evening, waiting 20 to 30 minutes after washing, using a pea-sized amount, moisturizing and wearing sunscreen.
- Do not use retinoids if you are pregnant or trying to become pregnant, unless a doctor says otherwise.
The retinoid family
All retinoids work through retinoic acid receptors in skin cells. Tretinoin is retinoic acid. Cosmetic forms have to be converted by the skin, step by step, into retinoic acid; each conversion step means a weaker, gentler effect.
| Name on the label | Status in the US | Strength | Typical use |
|---|---|---|---|
| Retinyl palmitate, retinyl acetate | Cosmetic | Mildest; several conversion steps | Moisturizers, very sensitive skin |
| Retinol | Cosmetic | Moderate; two steps | Anti-aging serums and creams |
| Retinal (retinaldehyde) | Cosmetic | Stronger; one step | Serums, often for experienced users |
| Adapalene 0.1% | OTC drug for acne | Strong, but often better tolerated than tretinoin | Acne, clogged pores |
| Tretinoin | Prescription | Strongest topical option | Acne, photoaging |
Rules differ by country. In the EU, for example, a 2024 regulation sets maximum concentrations of vitamin A (retinol and its esters) in cosmetics, and outside the US adapalene is often a pharmacy or prescription medicine. When you buy abroad, the same name can sit in a different legal category.
What the evidence shows
- Photoaging. The modern story began with a double-blind, vehicle-controlled trial by Weiss and colleagues in JAMA (1988), which showed that topical tretinoin improved fine wrinkles, roughness and pigmentation of sun-damaged skin. Many trials since have confirmed it.
- Retinol. A randomized, vehicle-controlled study by Kafi and colleagues (Archives of Dermatology, 2007) found that 0.4% retinol applied to the arms of older adults for 24 weeks improved fine wrinkling and increased markers of collagen production.
- Acne. Retinoids normalize the shedding of cells inside the pore and prevent the microcomedones from which acne lesions develop. Dermatology guidelines place topical retinoids among first-line acne treatments, often combined with benzoyl peroxide.
A 2006 overview by Mukherjee and colleagues in Clinical Interventions in Aging summarized the clinical efficacy and safety of retinoids for skin aging and noted that tretinoin is the best studied, with retinol and retinaldehyde showing smaller but real effects and better tolerance.
Starting without giving up
Irritation, often called "retinization" or the "retinoid uglies", is the main reason people stop: dryness, flaking, redness and stinging in the first weeks, sometimes with a brief worsening of acne. It usually fades as skin adapts. The AAD's advice for starting is very practical:
- Use it in the evening. Some retinoids break down in light, and the routine is easier to follow at night.
- Wait 20 to 30 minutes after washing so the skin is completely dry; damp skin increases penetration and irritation.
- Use a pea-sized amount for the whole face, avoiding the corners of the nose, the mouth and the eyes.
- Start every other night, or even twice a week, and increase only if skin is comfortable.
- Moisturize, either afterwards or in a "sandwich" (moisturizer, retinoid, moisturizer) if you are sensitive.
- Wear sunscreen every day. Retinoids can make skin more sensitive to sunburn, and UV undoes their benefits.
Acne usually takes 6 to 8 weeks to improve, sometimes longer, and changes in fine lines and pigmentation take several months. Judging a retinoid after two weeks is judging the irritation phase, not the result.
What not to combine, at least at first
- Exfoliating acids such as glycolic or lactic acid, including the 10% lactic acid serum we decode: alternate nights instead of layering.
- Benzoyl peroxide can degrade some forms of tretinoin when applied together; adapalene is stable with it, and combination products exist. Otherwise, use benzoyl peroxide in the morning and the retinoid at night.
- Physical scrubs, waxing and peels on retinoid-treated skin can cause raw patches. Stop a few days before facial waxing.
Gentle partners include hyaluronic acid, ceramide moisturizers and niacinamide. Our guide to combining active ingredients gives a full schedule.
Who should avoid retinoids
- Pregnancy and trying to conceive. Oral retinoids cause birth defects. Topical absorption is low, and the FDA noted when it approved adapalene for OTC use that there is no specific evidence that the topical gel causes birth defects when used as directed, but there are no adequate studies in pregnant women. Dermatologists generally advise avoiding retinoids during pregnancy; ask your doctor.
- Active eczema, rosacea flares or broken skin. Treat the flare first.
- Before procedures such as laser or deep peels, follow the practitioner's instructions.
Retinoids in a hot, sunny climate
Sun exposure is constant near the equator, and sweat and humidity make sunscreen wear off faster. Retinoids still work well there, but the morning routine has to keep up: a broad-spectrum SPF 30 or higher, enough of it, reapplied when you are outdoors. Some people in humid climates find they need less moisturizer on top of a retinoid than they did in a dry winter; others in heavily air-conditioned offices need more. Adjust after the first month rather than before.
Sources
- American Academy of Dermatology, "How to treat deep wrinkles" and "Acne: diagnosis and treatment", AAD, consulted October 2026.
- US Food and Drug Administration, "FDA approves Differin Gel 0.1% for over-the-counter use to treat acne", press announcement, 8 July 2016.
- Weiss J.S. et al., "Topical tretinoin improves photoaged skin. A double-blind vehicle-controlled study", JAMA, 1988.
- Kafi R. et al., "Improvement of naturally aged skin with vitamin A (retinol)", Archives of Dermatology, 2007.
- Mukherjee S. et al., "Retinoids in the treatment of skin aging: an overview of clinical efficacy and safety", Clinical Interventions in Aging, 2006.
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