Retinol, retinal and adapalene: the retinoid family explained

“Retinoid” gets used for everything from a drugstore night cream to a prescription acne gel. They’re related, but they’re not interchangeable, and in Canada the line between them is drawn quite clearly. Here’s how the family fits together, what each member can do, and how to use them without wrecking your skin in the first month.

What retinoids are and how they work

Retinoids are vitamin A and the molecules related to it. DermNet describes how they work: they bind to receptors inside the nucleus of skin cells and switch on genes that control how those cells grow and mature.

In practice, that does a few useful things. A 2025 review in Canadian Family Physician, which adapted the latest American Academy of Dermatology acne guidelines to Canadian practice, explains that topical retinoids speed up the turnover of cells lining the pore and make them less sticky, so pores are less likely to clog into blackheads and whiteheads. They’re also anti-inflammatory, help fade the dark marks pimples leave behind, and help keep acne clear once it’s under control.

For aging skin, DermNet notes that long-term tretinoin use (more than six months) reduces freckling, sun spots and fine wrinkles.

Meet the family

The key molecule is retinoic acid, the form that actually binds the receptors. Everything else is either a precursor your skin has to convert, or a lab-designed molecule that acts directly.

• Retinyl esters (retinyl palmitate, retinyl acetate): the mildest. A 2019 review in Postępy Dermatologii i Alergologii explains that skin must first turn them into retinol, then onward, so their effect is weaker.
• Retinol: the classic cosmetic form. It’s converted to retinoic acid in two steps, first to retinal, then to retinoic acid.
• Retinal (retinaldehyde): one step closer to retinoic acid. The same review describes it as less irritating than retinoic acid, with modest effects on wrinkles and texture.
• Tretinoin: retinoic acid itself, sold as a prescription drug.
• Adapalene, tazarotene and trifarotene: newer, lab-designed retinoids that target specific receptors. DermNet describes adapalene as the least irritating of the prescription options.

The Canadian review is clear that no single topical retinoid outperforms the others for acne; what matters is the concentration, the formula and whether you can tolerate it.

Cosmetic or prescription? How Canada draws the line

Health Canada regulates retinoids with two lists:

• The Prescription Drug List includes adapalene, tretinoin, tazarotene and trifarotene. In Canada, you need a prescription for all of them, whatever the strength.
• The Cosmetic Ingredient Hotlist, which sets what cosmetics may contain, prohibits retinoic acid in cosmetics outright. It allows retinol and its esters up to 1.0 percent total retinol equivalents in most cosmetics, and 0.2 percent in leave-on products meant for the whole body. Retinal is allowed up to 0.05 percent, or 0.01 percent in full-body leave-on products.

So a retinol serum from the beauty aisle is a cosmetic that can talk about smoother-looking skin. A tube of adapalene gel is a drug that treats acne, and it comes from the pharmacy counter with a prescription.

What the evidence shows

For acne, the evidence is behind the prescription retinoids. The Canadian review lists topical retinoids among the topical treatments that are the foundation for milder acne and advises combining treatments that work in different ways, such as a retinoid with benzoyl peroxide.

For aging skin, retinol has some independent support. In a 2007 University of Michigan trial, 36 older adults (average age 87) had a 0.4 percent retinol lotion applied to one arm and a plain lotion to the other for 24 weeks. The retinol side had significantly less fine wrinkling, and skin samples showed more collagen production. That’s a small study, on arms rather than faces, but it was well designed and not run by a manufacturer.

For cosmetic retinal and retinyl esters, the evidence is thinner. The 2019 review notes that the best balance between irritation and effect for retinol hasn’t been determined.

DermNet notes that acne takes 12 weeks or longer to improve on a topical retinoid. Patience is part of the treatment.

Irritation: the price of admission

The most common side effect is what DermNet calls retinoid dermatitis: redness, peeling and dryness, usually worst in the first weeks. The Canadian review lists dryness, burning, stinging, flaking and itching.

A few habits make it much more manageable, based on the Canadian review and DermNet:

• Start low and slow: a lower strength, or every other night, and build up as your skin adjusts.
• Use a thin layer over the whole area, not dabs on individual spots.
• Keep it away from the eyes, mouth and lips.
• Pair it with a gentle, non-comedogenic moisturizer.
• Be careful if you have eczema-prone skin; DermNet advises avoiding retinoids with eczema because they’re drying.
• Don’t stack it with other strong actives. The Canadian review notes most retinoids other than adapalene shouldn’t be combined with benzoyl peroxide, which can break them down.

If your skin is still raw, cracked or burning after a few weeks of careful use, stop and see your doctor or pharmacist.

Sun and pregnancy

Sun. Both DermNet and the Canadian review advise daily sunscreen when you use a topical retinoid. Most retinoids also break down in light, which is why they’re usually applied at night. Adapalene is more light-stable.

Pregnancy. Oral isotretinoin, the acne pill, causes serious birth defects. For creams, the Canadian review calls tazarotene a well-established cause of birth defects. For tretinoin and adapalene, studies haven’t found more birth defects or miscarriages, but people are still usually advised to avoid them in pregnancy because some is absorbed into the body. DermNet advises reliable contraception for anyone who could become pregnant while using a prescription retinoid. If you’re pregnant, planning to be or breastfeeding, talk to your doctor or pharmacist before using any retinoid, including cosmetic retinol. Azelaic acid is the acne treatment the Canadian review calls the choice in pregnancy.

You can browse the panel’s reviewed serums and treatments or filter for products suited to acne-prone skin.

Retinoids are some of the best-studied ingredients in dermatology, but the family runs from gentle cosmetic retinol to prescription drugs. In Canada, anything stronger than retinol or retinal needs a prescription. Whatever you use, go slowly, moisturize, wear sunscreen every day, and check with your doctor if you’re pregnant or planning to be.