Thread by @HarkerDavid

Per request of @GoodishIntent (and many others!), let’s talk about TOPICAL RETINOIDS.

#dermatology
#dermtwitter
#medtwitter

I’ve briefly discussed some of the mechanisms behind topical retinoids before, so this thread will focus on their practical use.

https://twitter.com/harkerdavid/status/950592484584894464?s=21

Topical retinoids are vitamin A derivatives that are commonly used in dermatology for acne, photoaging, and other skin conditions like psoriasis. Today let’s focus on their benefit combatting the damage done by that pesky fireball in the sky.

First off, besides causing skin cancer, sun exposure produces all kinds of changes in the skin, including coarse wrinkling, lentigines, solar elastosis, solar purpura, and thinning of the skin.

📷: @dermnet

As the saying goes, an ounce of prevention is worth a pound of cure. Regular sunscreen use and sun avoidance are mainstays of preventing photoaging. But if you’ve already got some sun damage, topical retinoids can help improve things, especially if started early on.

Topical retinoids come in both prescription and OTC forms. The OTC varieties, usually retinol or retinaldehyde, are retinoic acid precursors, and considered less potent than prescription retinoids.

There are studies that suggest certain formulations of OTC retinoids are as effective as the prescription variants, but these studies are often small, with short follow-up time, and funded by industry...

Adapalene (Differin) is a topical retinoid that recently became OTC, and is generally what I recommend patients try first.

After that, I move to tretinoin or tazarotene, both of which require prescriptions, and are available in various concentrations.

There are numerous studies attempting to compare all of these agents to each other. Results often vary, but the general consensus seems to be that topical retinoid effectiveness goes:

retinol/retinaldehyde < adapalene < tretinoin < tazarotene.

Topical retinoids should be applied as a thin layer (pea sized amount) to the entire face daily. Night-time application is usually recommend since tretinoin is photolabile. It usually takes at least 2-3 months to start seeing benefit, so patient and consistency are key.

Many people experience a “retinoid dermatitis” early in the course of therapy, with redness/peeling/stinging. This will improve with persistent use, but can be minimized by starting out with 2-3x weekly use and building up to daily over a couple of weeks. Moisturizers help also.

Topical retinoids also tend to make you more sensitive to the sun, so keep up with the sunscreen!

For women, the other main side effect to be aware of is teratogenicity. While systemic absorption is thought to be minimal, given how devastating retinoid embryopathy is, these agents should not be used in pregnancy.

So, in general it’s fine to start with OTC retinoids (retinol/retinaldehyde), but recognize that you’ll likely need prescription strength medication to get maximal benefit.

It’s also ok to start early! Almost every derm resident I know uses topical retinoids.

There are all kinds of fancy “cosmeceuticals” out there ($$$) but I think a basic regimen of a good sunscreen, moisturizer, and topical retinoid are all most people need.

Ping @nathanwpyle this is what happens with lots of “star damage”