Tretinoin
A potent retinoid that accelerates skin cell turnover and boosts collagen production.
What is Tretinoin?
CAS Number
302-79-4
Formula
C20H28O2
Molecular Weight
300.4 g/mol
Also known as: Retinoic acid, tretinoin, all-trans-Retinoic acid, Vitamin A acid, trans-Retinoic acid
What does Tretinoin do for skin?
Tretinoin, an all-trans retinoic acid, is a ligand for nuclear retinoic acid receptors (RARs α, β, γ). Upon binding, it modulates gene expression, influencing cellular proliferation, differentiation, and intercellular cohesion. In the skin, this leads to increased epidermal cell turnover, reduced follicular hyperkeratosis, inhibition of matrix metalloproteinases, and increased collagen synthesis in the dermis, collectively addressing acne, hyperpigmentation, and photoaging.
Typical concentration: 0.01-0.1% (most common prescription strengths are 0.025%, 0.05%, and 0.1% in creams, gels, or solutions). It is typically available as a prescription-only drug.
Is Tretinoin safe?
Tretinoin is an FDA-approved prescription drug for the treatment of acne vulgaris and photodamaged skin. Common adverse effects include local irritation, erythema, dryness, and peeling (retinization), especially during initial use. It is a known teratogen, contraindicated during pregnancy, and can increase photosensitivity.
What does the research say about Tretinoin?
Topical tretinoin (retinoic acid) in the treatment of photodamaged skin
Weiss, J. S., Ellis, C. N., Headington, J. T., Tincoff, T., Hamilton, T. A., & Voorhees, J. J. JAMA, 1988
Treatment of acne with topical tretinoin (all-trans-retinoic acid)
Kligman, A. M., Grove, E. W., & Leyden, J. J. Archives of Dermatology, 1976
The mechanism of action of topical retinoids
Shalita, S. H. Journal of the American Academy of Dermatology, 1993
Can I mix Tretinoin with other ingredients?
Retinoids and AHAs are both strong exfoliants. Using them together can cause severe irritation, redness, and barrier damage. Alternate on different nights.
Retinoids and BHA (salicylic acid) together can overdry skin and damage the moisture barrier. Use on alternate nights instead.
Benzoyl peroxide oxidizes retinol, making it inactive. They cancel each other out. Use benzoyl peroxide in the morning and retinoid at night.
Other Retinoids
Layering multiple retinoid products multiplies irritation without extra benefit. Choose one retinoid product per routine.
General guidance
Retinoids make skin photosensitive. Using retinoids in the morning increases sun damage risk. Always use retinoids at night only.
Sulfur
Sulfur and retinoids together cause extreme dryness and irritation. Never combine them in the same routine.
Retinoids and vitamin C have different pH needs. Together they may irritate and reduce effectiveness. Best to use vitamin C in AM, retinoid in PM.
Denatured Alcohol
Alcohol-based products increase dryness and irritation when used with retinoids. This can compromise your skin barrier.
PHAs
While PHAs are gentler than AHAs, combining with retinoids still increases exfoliation. Monitor for irritation.
Sulfur
Sulfur-based products can increase dryness when combined with retinoids. Use on alternate nights if needed.
Retinoid with azelaic acid is a potent combo. Both are effective individually. Start with alternating before layering.
Hydroquinone
Hydroquinone and retinoid together is a clinical protocol but increases irritation. Use under dermatologist guidance.
General guidance
Retinoids work best at night when your skin is in repair mode. PM application also avoids photosensitivity concerns.
Peptides
Retinoid + peptides is a powerful anti-aging duo. Peptides signal collagen production while retinoids boost cell turnover.
Ceramides help counteract retinoid dryness. Apply ceramide moisturizer after retinoid for better tolerance.
Hyaluronic acid before retinoid helps buffer irritation and keeps skin hydrated. A great way to ease into retinoids.
Great combo! Niacinamide soothes inflammation and strengthens the barrier, making retinoid easier to tolerate.
Bakuchiol is a gentle retinol alternative. No need to use both unless you want to boost results. Bakuchiol is safer during pregnancy.
Squalane after retinoid helps lock in moisture and reduce dryness. It's non-comedogenic so it won't clog pores.
Azelaic acid and retinoid can work well together for acne and anti-aging. Start slow and build tolerance.
Centella asiatica is excellent alongside retinoids. It soothes the irritation and redness that retinoids can cause, making your retinoid routine more tolerable.
Tranexamic acid and retinoids are a powerful combination for hyperpigmentation. TXA blocks melanin transfer while retinoids accelerate cell turnover — they work through different pathways and are safe together in PM routines.
Vitamin E protects retinol from oxidation and helps buffer irritation. Many retinol formulas include vitamin E for exactly this reason — a smart combination for your PM routine.
Read all ingredient interaction guides for layering order and science-backed advice.