Description
Tretinoin is all-trans retinoic acid, the biologically active acid form of vitamin A. It is applied to the skin and is chemically closely related to isotretinoin (13-cis retinoic acid), which is taken orally. It was developed in the 1960s for acne research and has since become one of the most studied topical retinoids.
According to studies, tretinoin binds to the retinoic acid receptors in the cell nucleus and changes gene expression in the skin: the outer skin layer renews faster, clogged follicles loosen and increased collagen formation is observed in the dermis.
In research on light-induced skin aging, tretinoin is the reference compound. Double-blind, vehicle-controlled studies document fewer fine wrinkles, more even pigmentation and, histologically, a thicker epidermis with new collagen fibers over 16 to 48 weeks. A study in the New England Journal of Medicine also shows that tretinoin inhibits the collagen-degrading enzymes triggered by UV light by 70 to 80%.
The concentrations studied were mostly 0.025 to 0.1%. The 0.05% and 0.1% strengths listed here fall right within that range.
You get tretinoin in a 20 g tube, in concentrations of 0.05% and 0.1%.
This information is for research and educational purposes only. No medical advice.
Risks & Safety
Tretinoin is well studied on the skin, but regularly irritates it. The higher the concentration, the stronger the irritation.
Observed in studies and user reports:
- Skin irritation: redness, scaling, burning and dryness are the most common effect, especially in the first weeks. A comparative study found clearly more irritation at 0.1% than at 0.025%, with the same effect. The 0.05% and 0.1% strengths listed here fall within this range, 0.1% at its upper end.
- Sensitivity to light: treated skin reacts more sensitively to sunlight.
- Pregnancy: as a retinoid, tretinoin is excluded during pregnancy in the literature, even though little is absorbed through the skin.
- Other retinoids: together with oral isotretinoin or other retinoids on the skin, dryness and irritation add up.
This assessment does not replace medical advice. Risk and responsibility for any actual use lie entirely with the buyer.
Studies
- Topical tretinoin for photoaged skin - Journal of the American Academy of Dermatology 1986, Kligman et al: 0.05% tretinoin cream versus vehicle, light and electron microscopic changes in photoaged skin.
- Topical tretinoin improves photoaged skin. A double-blind vehicle-controlled study - JAMA 1988, Weiss et al: 16-week double-blind study with 30 participants, improvement on forearm and face versus vehicle.
- Two concentrations of topical tretinoin (retinoic acid) cause similar improvement of photoaging but different degrees of irritation - Archives of Dermatology 1995, Griffiths et al: 0.1% versus 0.025% over 48 weeks, same effect, more irritation at the higher concentration.
- Pathophysiology of premature skin aging induced by ultraviolet light - New England Journal of Medicine 1997, Fisher et al: UV light raises collagen-degrading enzymes, pretreatment with tretinoin inhibits them by 70 to 80%.
- Topical tretinoin for hair growth promotion - Journal of the American Academy of Dermatology 1986, Bazzano et al: tretinoin alone and together with topical minoxidil in hereditary hair loss, 56 participants over one year.
