We’ve said it before and we’ll say it again: the most effective weapons in the acne battle are vitamin A derivatives. And since vitamin A derivatives are proven to repair photodamage, they're also the go-to ingredients when it comes to tackling aging issues. Almost everyone can benefit from a topical vitamin A, but confusion reigns over what actually works, and facts can be drowned out by resounding marketing clamor. It’s enough to scare some people from using them altogether. Read on to learn about the difference between retinoids and retinols so that you can choose the right product for your skin.

A Crash Course in Retinoids

Retinoids

Retinoids are the group of vitamin A derivatives that have been proven, study after study, to unclog pores, stimulate collagen production and improve collagen density. The active ingredient that repairs photoaging and alleviates acne is retinoic acid. Your skin is only able use retinoids that are—or can be converted to—retinoic acid, because retinoic acid works by binding to retinoic acid receptors found on the outer membrane of cells. On the acne-fighting front, it penetrates to sebaceous glands and reduces sebum production by binding to sebocyte receptors. Its anti-inflammatory effects keep P. acnes in check.

Currently, there are three prescription-strength retinoids on the market: Tretinoin (includes Retin-A, Retin-A micro and Renova), Tazarotene and Adapalene. Tazarotene is regarded as the strongest and Adapalene the gentlest to the skin. There is no argument that prescription formulas deliver the best results, but there are drawbacks—the most common being potential irritation, redness and peeling.

Most, if not all, prescription products contain ingredients like propylene glycol and parabens that the natural community long ago rejected. I suspect that some of this irritation might due to non-active ingredients in the formulation, rather than the retinoic acid, itself, and could potentially be mediated by using formulations that do not contain other known irritants.

Retinol

The most popular version of vitamin A found in over-the-counter products is called retinol. Retinol is not retinoic acid—retinol works because it converts to retinoic acid. But there are also various types of esters, also derivatives of vitamin A, that are often described as retinol: Retinyl Acetate, Retinyl Linoleate, Retinyl Palmitate and Retinyl Proprionate. It's important to remember that all vitamin A derivatives must convert to retinoic acid. Their effectiveness depends on several factors:

1. Number of conversion steps: Vitamin A esters like Retinyl palmitate have a three–step process (Retinyl palmitate◊retinol), while retinol takes two steps to convert to retinoic acid (retinol◊retinaldehyde◊retinoic acid). The drawn-out conversion process of Retinyl palmitate militates against its efficacy.
2. Stability: All vitamin A derivatives degrade very quickly when exposed to air and sunlight. In fact, dermatologists favored prescription retinoic acid over retinol for decades because the latter was simply too unstable in solution to be effective. Fortunately, advances in nanotechnology have given us encapsulated versions of retinol that do not degrade as quickly. It's still important to keep your retinol product away from light and use the product only at night.
3. Concentration: The efficacy of retinol depends on concentration—higher concentrations result in higher conversion rates to retinoic acid. However, higher concentrations of retinol can sometimes lead to increased irritation, the same problem encountered with, for example, prescription-strength Retin-A. The upside here is that if you experience irritation when using a high-concentration retinol product without known irritating preservatives (parabens or sodium benzoate), you are very likely reaping the benefits of retinoic acid being absorbed into the skin’s cell receptors.

How to Choose the Right Product

Adults with both acne and aging issues will want to get the full benefit of retinoic acid if they can tolerate it. Some people experience irritation at first, which generally improves over time. If not, your dermatologist may decide to try a different prescription. If irritation persists, it may be due to other ingredients in the formula, such as preservatives.

If you’re concerned about skin reactivity, you may want to consider an over-the-counter retinol product. But beware—sometimes the reason an over-the-counter retinol product is less irritating is because its retinol concentration is so low it’s doing nothing. Effective products do exist, but look for a product with the following profile:

• Contains an encapsulated version of retinol (protects against degradation)
• Contains an effective concentration of retinol
• Does not contain retinyl palmitate or other vitamin A ester (too far removed in the conversion chain)
• Does not contain preservatives like parabens, phenoxyethanol or sodium benzoate that may irritate skin

Some cautionaries:

Prescription retinoids are regulated because they are teratogenic. Pregnant and nursing women should also avoid retinol products.

Use at night only, and always wear a broad-spectrum SPF 30 sunscreen during the day.

Keep all retinoid products away from light.

Never use benzoyl peroxide products, especially if you are an adult with acne. Prolonged use of BP can make skin photosensitive, and it impedes new skin cell formation, both of which accelerate skin aging.

https://www.marieveronique.com/blogs/science-research/retinol-vs-retinoid-how-to-choose-the-right-vitamin-a-derivative