Retinoids are a class of Vitamin A derivatives that are antioxidant, cell regenerating, and cell communicating and whose anti-aging effects are well documented. Retinoids reduce fine lines, increase epidermal thickness and stratum corneum compaction, reduce melanin content (which causes hyperpigmentation) and synthesize collagen. They become active on skin through a two-part enzymatic oxidation process. First retinol is converted within skin to retinaldehyde, then to trans retinoic acid. Retinol oxidation is optimized at a neutral pH, meaning it is most active at a higher (less acidic) or more neutral pH. This is why acids like Lactic or Glycolic acid or Vitamin C should not be used simultaneously with retinoids. Unlike AHAs, which operate from the outermost layers inward, retinoids activate in the dermis outward to accelerate cell turnover. This shows up as flaking on the skin, which is often mistaken as exfoliation (too strong concentrations may also lead to irritation and flaking).
Important Skin & Beauty Tips:
Like AHAs, retinoids thin the epidermal wall, which often means more sensitive and easy to damage skin. Take care when introducing retinoids and baby your skin for the first couple of weeks. Slowly increase frequency of applications and be judicious when adding back in exfoliation methods. Weak skin is not healthy skin.
To counteract transdermal water loss that occurs through retinoid use, use a topical humectant such as honey, or hyaluronic acid applied in a humid climate (or steamy room in desert climates) to attract moisture to skin.
Reminder: retinoids and AHAs do not work well together, so if you are using both in an anti-aging regimen, wait at least 30 minutes between applications. Better yet, wait 24 hours.
Retinoids cause sun sensitivity, and because they weaken and (temporarily) thin skin, can cause infection and, paradoxically, increased hyperpigmentation. ALWAYS wear sunscreen when using retinoids.
You will start to see the effects of retinoids after about 12 weeks. After about a year, you may notice a diminution of effect on your skin. This skin fatigue was noted by Retin-A inventor Albert Kligman, M.D., who recommended maintenance retinoid application of 3x per week. Other options are to stop for a month (not more), or get a stronger dilution of retinoids.