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Retinoids: A guide to Vitamin A in Skincare

Retinoids: A guide to Vitamin A in Skincare

Retinoids are one of the most researched and effective categories of skincare ingredients. They can improve a variety of skin concerns, making them highly popular with experienced skincare users.

But they’re also not always the most user friendly, with the more potent retinoids causing significant irritation when you’re just starting and many retinoids being prescription-only. So we’ve set out to answer all the practical questions related to retinoid usage…. and fill in some of the missing puzzle pieces along the way, like how retinoids interact with our cells.

What is a Retinoid?

A retinoid is an umbrella term that covers all of the different Vitamin A derivatives. The ones used in skincare are synthesized in a lab and either come already in bioactive form or they’ll need to be able to be converted within our skin (I’ll explain this further in the next section). The level of evidence behind them can vary and the best option for you will depend on your unique skin needs.

While we consume Vitamin A through our diet and oral Vitamin A can also benefit our skin, overconsumption via supplements and dietary sources can result in toxicity if you’re not careful as Vitamin A accumulates in our fat cells. For this reason, skincare products with Vitamin A allow us to better target our skin without the risk of hypervitaminosis.

Active Forms and Conversion

The retinoid you choose will influence how long it takes to work, how much irritation you experience, and how significant the results are. But with so many different options now, it can get overwhelming.

Think of a retinoid like a potato. Yep, a potato. You can buy a regular old potato at the grocery store to make French fries, but you’ll have to wash, peel, chop, and cook it. You can also save some work and buy the already chopped ones - or better yet, buy some French fries from McDonald’s and there’s no preparation needed. But what if every time you wanted some potatoes, you had to travel to a farm and harvest them before preparing them? This is going to decrease the chances of French fries ending up on your plate that night.


Tretinoin and the other prescription forms are already in active form and immediately start working within the skin. Tretinoin is a form of retinoic acid, and retinoic acid is the ingredient that does all that great work within your skin. So you could say that tretinoin = French fries.

Meanwhile, skincare products that contain retinol, retinyl palmitate, and retinaldehyde all need to be converted into that active retinoic acid within our skin. Some of them take more work than others, like our pre-chopped bag of taters vs going out to a farm to dig them up first. 

Here’s the conversion order; the more conversions your retinoid has to go through before it reaches the active retinoic acid form, the longer it will take and the less potent it will be:


The more conversions required, the longer it takes for results: tretinoin takes only 3-4 months to start taking effect while needs requires 6 months. And for something requiring many, many conversions - like beta carotene - it’s a bit of a question mask in terms of whether any of it ends up as retinoic acid.

Retinol Esters: retinyl palmitate, retinyl propionate, retinyl acetate

3 conversions required

As the name suggests, these are esters of retinol. That means that once they get into the skin and taken up into the cells, they’ll need to be oxidized to retinol, then retinaldehyde, then retinoic acid. None of them are particularly well studied and honestly, in my opinion, there’s just better options.


2 conversions required

This is the OG of the retail retinoids. While a lot of the hype is focused on newer retinoids these days, retinol (ROL) remains the most studied retinoid available without a prescription. It’s been used since the 1980s with research on its skin benefits starting in 1995 and appears to work similarly to tretinoin with less irritation and dryness. Because stability can be an issue, we suggest encapsulated retinol.


1 conversion required

Retinaldehyde (RAL) is only one conversion away from retinoic acid and preliminary studies show it performs as well as tretinoin. Like encapsulated retinol, it’s well tolerated with the added benefit of being antibacterial for those who are acne-prone. The main drawback at this time is that more long term studies are needed.

Retinoic Acid Esters: retinyl retinoate, hydroxypinacolone retinoate, sodium retinoyl retinoate, ethyl lactyl retinoate

1 conversion required

Retinoic acid esters are similar to retinaldehyde (RA) in that they are one conversion away from active form. Rather than being oxidized from RAL to RA, they break down into separate molecules when applied to the skin. Retinyl retinoate separates into retinoic acid and retinol, meaning one part is in active form while the rest undergoes oxidation like usual. Ethyl lactyl retinoate and sodium retinoyl hyaluronate are retinoic acid molecules bound to another ingredient so they break down to RA and either lactic acid or sodium hyaluronate. While the retinoic acid esters are interesting, there’s no real research yet.  

Retinoic Acid: tretinoin, adapalene, tazarotene, trifarotene

active form 

Tretinoin is the original form of retinoic acid (RA) and considered a “gold standard therapy” for photoaging and acne. It’s been used in dermatology since the 1960s and has a huge body of research behind it. Newer generation retinoids like adapalene and tazarotene came later followed by trifarotene. The newer retinoids are also in active form but they’re generally better tolerated due to their selectivity (attraction) for specific receptors. The main drawback to any prescription strength retinoid will be the irritation and dryness, which can be so significant that it prevents continued use. Plus, the newer ones don’t have the same body of evidence that tretinoin does.

All retinoids will have similar benefits as far as normalizing the shedding of dead skin cells, improving texture and photoaging, and stimulating cell turnover. You’ll want to balance what is most researched with what your skin can tolerate - consistency is the most important part.

How Retinoids Work

We hear all the time about the benefits of retinoids but rarely do we get into the specifics of how they interact with our skin. Let’s follow a retinoid on its journey, starting from when it’s applied to our skin:

  • Upon application, retinoids are able to easily penetrate past the skin barrier due to their lipophilic (oil loving) properties. At this point, retinoic acid esters should start to break down into separate molecules and then all retinoids are taken up by our cells.
  • Once in the cell, the various retinoids will undergo a redox reaction to convert them to a usable form. The oxidation of retinol to retinaldehyde is catalyzed (kicked into gear) by either the enzyme retinol dehydrogenase or alcohol dehydrogenase. Then retinaldehyde is oxidized to retinoic acid by the enzyme retinal dehydrogenase. 

This is very different from most skincare which improves the appearance and function of the skin barrier. That’s why retinoids are so powerful: they can stimulate cell turnover and regulate cell growth from the inside out.

Now, let’s tie it all together. We’ve broken down how retinoids can influence a cell via its “control center” but how does this impact your skin? It depends on the cell in question. Keratinocytes are the most common skin cell in the epidermis (upper skin layer) and retinoids make them divide and grow faster. They also act on fibroblasts within the dermis (the part that keeps your skin bouncy) so they produce more collagen while “turning off” the enzymes that break down existing collagen. Retinoids essentially improve the functioning of the skin, correcting issues like acne and sun damage in the process.

Using a Retinoid 

 The biggest obstacle to getting all the amazing benefits from a retinoid is actually using the retinoid. Retinoids can be potent and it’s easy to underestimate them, especially as irritation doesn’t show up immediately. Here’s everything you need to know, from those of us who learned it the hard way.

Unless you choose a very gentle option, just know there will be a 6-8 week retinization process where your skin will get irritated, flaky, and may even break out as it acclimates to the retinoid. While it’s no walk in the park, taking the time to get your skincare routine ready and slowly adding in your retinoid can make a world of difference.

After that, it’s a waiting game. Don’t quit because you’re not seeing a skin transformation after a month or two. Expect 3-6 months to start seeing results and ayear or more for the most significant changes to become apparent. Especially with signs of skin aging, it didn’t happen overnight and neither will results.

If you remember nothing else, remember that slow and steady wins the race with retinoids. 


  • Pause exfoliants and anything potentially irritating
  • Make sure you have a gentle routine in place with lots of hydration and barrier support
  • Don’t race into it, make sure you feel confident using your new retinoid before you begin.
  • Retinoic acid interacts with retinoic acid receptors in the nucleus of the cell (the control center of the cell where DNA is stored). From here, RA is able to turn on and off gene expression that relates to cell proliferation and differentiation AKA the growth and development of cells.

In simple terms, our skin cells convert retinoids into a usable form so that they can then go bind with retinoic acid receptors in the control center of our cells - like turning a key in a lock. This activates genes and enables retinoids to produce a biological response.

How to Begin:

  • Start by using your retinoid every 3rd or 4th night only
  • For sensitive skin and more potent retinoids, utilize methods to slow the rate of penetration (apply 2 hours after cleansing and/or apply a moisturizer first)
  • Only use the amount directed and avoid sensitive areas like the eyes, corners of the mouth, and nostrils
  • For more potent retinoids, dot over the face and then blend for more even distribution
  • Space out changes in concentration or frequency of use by 2 weeks
  • Don’t add back exfoliants until your skin is fully acclimated

Does using prescription retinoids sound intimidating? Our Stratia Night Shift is the perfect beginner retinoid, combining low-dose encapsulated retinol with a ceramide-enriched cream. This is a great way to get started and is also the perfect option for sensitive skin and more minimalistic routines. 

Frequently Asked Questions

Do retinoids thin your skin?

No, this is a myth. They make the skin barrier more compact while thickening the rest of the epidermis but both of these effects are temporary. Over time, retinoids thicken the skin by increasing the collagen and elastin in the dermis.

Do retinoids make you more sun sensitive?

Technically yes, but this is a result of the temporary barrier disruption we see while your skin is acclimating and it’s temporary.

Are there any ingredients I can’t use retinoids with?

Non-encapsulated retinol and tretinoin cream shouldn’t be used at the same time as benzoyl peroxide in leave-on formulas. Everything else is fine if your skin tolerates it.

Will everyone purge?

No, purging is believed to be caused by increased irritation during the acclimation period and it’s going to be more common in acne prone skin. Many people don’t experience purging at all.