I am always asked questions about retinoids, retinols, vitamin A derivatives, and their role in skin care. After all, they are generally accepted to be a gold standard ingredient in anti-aging skin care. As much interest as there is around this ingredient category, there is even more confusion (and misconceptions, and misinformation which unfortunately skin care companies often contribute to).

I asked my Dad, Dr. Luigi Polla, to clarify a few things.

Forms

Vitamin A and its derivatives exist in various forms when used in cosmetic formulations. The most widely used forms include retinol, retinyl esters (such as retinyl acetate, retinyl propionate, and retinyl palmitate), and retinaldehyde. Through various enzymatic reactions in the skin, all of these forms are ultimately converted to all-trans-retinoic acid (also known as tretinoin), which is the active form of vitamin A in the skin.

Retinol and its esters are insoluble in water but soluble in organic oils and solvents. Retinol is in the form of light yellow crystals. Esters such as acetate or palmitate of vitamin A are yellow oils. Hence retinol-based formulations will often have a yellowish tint to them.

Products containing retinoic acid require a medical prescription (think of brands such brand names Aberela, Airol, A-Ret, Atralin, Avita, Retacnyl, Refissa, Renova, Retin-A, Retino-A, ReTrieve, or Stieva-A). The most common strengths are 0.025%, 0.05% and 0.1%.).

In contrast, products containing retinol, proretinol, retinaldehyde do not (meaning these are the forms typically found in over the counter cosmetic creams and serums). The brands offering products containing such ingredients are too numerous to list – indeed, most skin care brands will have this ingredient in their product portfolio.

Benefits

Retinoic acid is effective in decreasing acne blemishes – indeed this was its first intended use in dermatology (discovered in 1969 by James Fulton and Albert Kligman).

Retinoic acid ensures an effective turnover of cells within the follicle, with more effective disposal of dead cells. It thereby prevents the formation of “plugs” that block the opening of the follicle, thus preventing the formation of blackheads, whiteheads, and pimples.

Retinoic acid has also been found effective in the treatment of photoaging and aging skin.

One of its key anti-aging benefits is an increase in the skin’s thickness. While you may not think of “thick skin” as something to strive towards, thicker skin (brought about by increased collagen) is directly correlated to a decrease in fine lines and wrinkles.

Indeed, retinoic acid both inhibits production of collagenase and stimulates the production of glycosaminoglycans in the skin. Retinoic acid also stimulates growth of keratinocytes and fibroblasts and stimulated extracellular matrix production by fibroblasts. The conclusion: a reduction in fine lines and wrinkles

Challenges

There are definite challenges when working with retinoic acid. These include:

Instability especially to oxygen and light.

Look for products packaged in tubes that are opaque and impermeable to oxygen. Tubes are typically preferable to jars (given the smaller opening and thus diminished access to air and light).

Skin irritation

Retinoic acid (and other forms of this ingredient) induces skin irritation, which negatively affects skin barrier properties. Within two weeks of starting to use a retinoid product, the skin may become irritated, meaning red and feeling like there is a constant slight stinging. While high doses of retinoids will increase the beneficial results of the treatment, the associated irritation tends to define the upper concentration limit that a consumer can tolerate. While the skin may have some capacity to tolerate increasing doses of retinoids as it becomes more used to this ingredient, irritation is not completely eliminated even with long-term use.

Of the forms allowed in non-prescription products, retinol is becoming increasingly present in cosmetic formulations. One reason for this is that retinol has been shown to be less irritating topically than retinoic acid.

Dr. Polla’s recommendations

“I recommend our Advanced Retinol Serum to many of my patients, typically to those who are 40 years old and over. Younger skin types tend to be even more sensitive to potential side effects, so I tend to avoid retinoids until that age. Also, retinoids can be recommended for all skin types, but typically is best tolerated by oilier, thicker skin types. Remember never to recommend products containing any type of retinoid to nursing or pregnant women.”

“Instructing patients to apply their retinoid to dry skin can minimize retinoid dermatitis. Patients should be advised to wait 15 minutes after washing the face to apply a topical retinoid. Wet skin enhances the penetration of the retinoid into the dermis, thus exacerbating irritation.”

“A gradual increase in application frequency can also help to minimize irritation. The patient should apply the retinoid starting every other night or every third evening for the first one to two weeks of treatment. The patient can then gradually increase the frequency to nightly use as tolerated. Tolerance is often achieved in three to four weeks.”

“It is important that the topical retinoid applied at night-time for two reasons. First, patients who use topical retinoids during the daytime notice increased sensitivity to ultraviolet light. Second, trans-retinoic acid is unstable when exposed to sunlight. When exposed to light, 50% of trans-retinoic acid is degraded in two hours.”

“It is essential be particularly careful with sun protection when using a topical retinoid product. Avoiding the sun and an SPF of 20 or more is key, given the skin’s heightened photo-sensitivity.”

“Retinoids can lead to dryness and flaking. A nourishing moisturizers applied during the daytime is to avoid excessive dryness is key. However, keep in mind that retinoic acid should not be applied at the same time as moisturizers, since this combination may cause adverse effects.”