Vitamin A and the Skin
Retinoids are a family of compounds derived from vitamin A that have been studied in dermatology for more than 50 years. They influence how skin cells grow, mature and communicate, making them one of the most extensively researched classes of topical dermatological agents.
Within the skin, retinoids bind to specific nuclear receptors known as retinoic acid receptors (RARs) and retinoid X receptors (RXRs). Activation of these receptors changes the expression of hundreds of genes involved in epidermal differentiation, keratinisation and extracellular matrix biology.
Epidermal Cell Turnover
The epidermis continuously renews itself through a process known as epidermal turnover. New keratinocytes are produced in the basal layer before migrating toward the surface, where they eventually form the stratum corneum and are naturally shed.
Research has shown that retinoids influence this process by normalising keratinocyte differentiation and reducing abnormal cohesion between cells within the follicular opening. This contributes to smoother skin texture and more regular epidermal organisation.
Collagen and Photoageing
One of the most extensively investigated effects of topical retinoids is their influence on photoaged skin.
Ultraviolet radiation increases enzymes called matrix metalloproteinases (MMPs), which degrade collagen within the dermis. Studies have found that retinoid therapy can reduce MMP activity while increasing the production of procollagen, helping improve the appearance of photoaged skin over time.
Clinical Evidence
Multiple randomised controlled trials have evaluated topical tretinoin for photoaged skin. Across these studies, consistent improvements have been reported in measures such as:
- Fine wrinkling
- Skin roughness
- Mottled pigmentation
- Overall photodamage
Visible improvements typically occur gradually over several months rather than days or weeks.
The Importance of Consistency
Dermatology literature consistently reports that skin remodelling is a gradual biological process. Because epidermal renewal and collagen synthesis take time, improvements are generally associated with regular long-term use rather than immediate effects.
Common Early Effects
During the first weeks of treatment, some individuals experience temporary dryness, scaling, redness or irritation as the skin adapts. This period is commonly referred to clinically as the retinisation phase. Appropriate moisturisation and daily broad-spectrum sunscreen are commonly recommended as part of an overall skincare routine.
Selected References
- Kligman AM, Grove GL, Hirose R, Leyden JJ. Topical tretinoin for photoaged skin. J Am Acad Dermatol. 1986.
- Kang S, et al. Topical tretinoin improves photodamaged skin. J Am Acad Dermatol.
- Fisher GJ, et al. Mechanisms of photoaging and retinoid effects on human skin. Nature/Journal of Investigative Dermatology research.
- American Academy of Dermatology guidance on topical retinoids.