It’s the question everyone asks and shouldn't, because comparing retinol percentages is like comparing apples to oranges. Every form of Vitamin A has its own degree of potency, side effects and efficacy.
To refresh, the four kinds of Vitamin A are:
- Retinyl esters (e.g., retinyl palmitate)
- Retinal (e.g., retinaldehyde)
- Retinoic Acid (available by prescription only, the product is called tretinoin, the generic name for Retin-A)
All forms of Vitamin A end up converting into retinoic acid; therefore, all the benefits that come from Vitamin A come from its active form, retinoic acid.
There’s no one-size-fits-all magic number
When determining retinol percentages, keep in mind, everyone has varying skin concerns, degrees of damage and skin types. Your friend might be able to start with the highest percentage, while that same amount might cause your skin to freak out.
Fun fact: Everyone has different levels of retinoic acid already present in their skin. Retinol works cumulatively in the skin, which explains why you can work up (or “titrate”) to higher levels of retinol over time as your retinoic acid levels are increased.
For retinoic acid, percentages are easier to digest because they are consistent. There are three standard percentages of prescriptive retinoic acid: 0.025%, 0.05%, and 0.1%. Most dermatologists will start you on a 0.025% and slowly advance the concentration over time, with visible results seen as early as six weeks or as late as six months. It all depends on how your skin reacts and acclimates.
Here’s where it gets tricky
Retinol percentages in OTC products are where things get hairy. Because retinoic acid is dosed in percentages, this is how the retail world presents retinol. However, it’s quite misleading if you don’t understand there are multiple types of retinol—each with a different level of potency. For example, a product that contains 1% retinyl is definitely not as effective as a product that contains 1% retinaldehyde. And what’s more confusing? Both these products are likely to market themselves as simply a retinol product without distinguishing which type of retinol they’re using.
Another example: if a product contains a blend of .5% retinyl palmitate and 1% retinol, is the correct percentage to claim 1.5%? Technically, no. Because retinyl palmitate is about 20% less potent than retinol, it’s not an accurate comparison.
In sum: all retinol is not created equal. Don’t just rely on the percentages (and what’s written on packages). Make sure you know what kind of retinol you’re getting before making a decision.