Retin-A, specifically, has become the catchall for almost all prescription-strength vitamin A derivatives—sometimes it’s even mistakenly used to describe over-the-counter retinoids too (those are technically called retinols, though). Compare it to facial napkins: You may ask someone to kindly pass you a Kleenex, when you’re not really asking for that specific brand—you’re just referring to any tissue. Or more aptly, perhaps you ask a friend for an Advil when you have an ache; you are likely just looking for any form of ibuprofen. How did Retin-A get so lucky to become the proprietary eponym? Easy: It was the first. Debuting as a patented, FDA-approved acne-treatment in the early ’70s, it quickly became equally loved for its healthy aging benefits too. After the patent expired, generic versions (tretinoin) and other brand name versions with slightly different formulas popped up (like Tazorac and Differin). Less potent OTC options appeared, too. But Retin-A has remained the most recognizable. One of the most notorious side effects is the dry skin, flaking, and redness that come in the first few weeks. “Typically, it does cause initial irritation as the skin acclimates. This tends to subside over consistent use,” says Hermann. Finally, some people simply find the ingredient too harsh—and no transition period will get you to the other side. “For those with rosacea or sensitive skin, Retin-A can be difficult to tolerate,” says Hermann. This is because these individuals may already have a compromised skin barrier—and so accelerating skin cell turnover will only lead to more permeable and irritated skin. As for the amount, “less is more,” says Hermann. “Typically a pea-size amount of cream is all that is needed for the entire face. If you have trouble spreading it, it can be mixed with a little light moisturizer or serum to help it spread farther.” Or, as a tip from Zeichner: If you tend to have easily irritated skin, you can layer your Retin-A on top of your moisturizer. This way, the ingredient is buffered by your hydrating ingredients and doesn’t penetrate the skin as easily.
