Ep 30: Which Retinoid is Right for You? The Science of Vitamin A in Skincare

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You can't talk about skincare for more than five minutes without someone bringing up retinol. But the thing is, retinol is just one piece of a much bigger picture, and most of the information floating around out there skips the part that actually makes it interesting. As your cosmetic chemist besties, we're here to fix that!

First, let's clear up the terminology

"Retinoids" and "retinol" are not the same thing, even though people use them interchangeably constantly (and we even make that mistake sometimes too!) Retinoids is the umbrella term for a whole family of ingredients. Retinol is just one member of that family.

What all retinoids have in common is that your skin can convert them into something called retinoic acid, and this is the molecule that actually does the work.

This is important enough to say twice: none of the retinoids you put on your face technically do anything until your skin converts them into retinoic acid. That's the form your skin can actually use, and everything else takes a few steps to get there.

Why retinoic acid matters so much

Your body needs vitamin A to make retinoic acid, and retinoic acid is one of those molecules that functions like a key in a lock. Your cells follow a pretty strict roadmap: reactions happen in sequence, like dominos. Retinoic acid is what pushes those dominos over and keeps the chain moving. It activates the cell growth pathway.

When you apply a topical retinoid, what you're ultimately trying to do is get more retinoic acid into your skin cells so that the cell turnover process speeds up. As we age, skin cells get damaged and their normal shed-and-renew cycle slows down. You end up with buildup, which can lead to uneven texture, clogged pores, and persistent dark spots. Basically all of the things you don't want to happen to your skin.

Speeding up that cycle means your skin stays more consistently fresh. And as a bonus, retinoids also increase collagen production, which is the protein that gives skin its structure and firmness.

The four types of retinoids, ranked by how much work your skin has to do

Here's the conversion chain, from most steps to fewest:

1. Retinyl esters (like retinyl palmitate)

2. Retinol

3. Retinal (retinaldehyde)

4. Retinoic acid (tretinoin)

Retinyl palmitate has to be converted into retinol, then retinal, then retinoic acid before your skin can actually use it. Retinol skips one step, and retinal skips two. And if you apply retinoic acid directly (which you can only do with a prescription), it's immediately available, no conversion needed.

This is what people mean when they say a retinoid is "less potent." It's not that it doesn't work, it's that it requires more steps to get there.

So why not just use prescription tretinoin?

Good question, and the answer is nuanced. One huge advantage of the earlier forms (retinol, retinal, retinyl esters) is that the first three conversion steps are reversible. Your skin can convert retinol into retinoic acid as it needs it, and back again if it has enough. Once the molecule becomes retinoic acid, that process is one-way. It can't convert back.

That means applying retinol gives your skin a kind of built-in pacing mechanism. It converts what it can use and holds onto the rest. Applying straight retinoic acid floods your skin with the active form all at once, which is more effective for certain things but also a lot more irritating for most people.

Also, isotretinoin (Accutane) is in this family. It has an almost identical structure to tretinoin, it just has a bend in the molecule. Both are prescription-only, but one is topical (tretinoin) and the other one is oral (isotretinoin).

Why retinoids cause irritation

Retinoids increase cell production AND loosen the bonds between cells, which makes it easier for dead skin to shed. Normally, that's the point. But if you go too hard too fast, it's basically like over-exfoliating: itching, redness, burning, and general unhappiness.

If you have a lot of dead skin buildup, a higher-potency retinoid might actually help move that along faster. If your skin is already pretty healthy and you jump straight to prescription-strength retinoic acid, you're going to have a bad time.

You don't have to avoid retinoids, just start lower and work up based on what your skin is actually doing.

The bottom line

Retinoids are one of the most well-studied ingredient categories in skincare, and they work WELL. The best retinoid isn't necessarily the strongest one; it's the one your skin can tolerate consistently, because consistent use is what actually produces results.

Start low. Go slow. And understand what you're actually putting on your face.