A Complete Guide to Retinoids
Retinoids. There’s a lot of confusion and maybe even a little fear behind these infamous skincare ingredients. As you are already well aware, we have a background in molecular and biochemical science, and we apply the limited knowledge from our studies to creating skincare routines that should—in theory—work. However, we are not dermatologists, estheticians, or any other medical professionals that are capable of recommending specific skincare routines to you and your particular skin’s needs.
What exactly is retinoid?
Retinoid is a blanket-term for derivatives of Vitamin A, which has many, many important functions for healthy growth and maintenance, but in terms of topical application for skincare purposes, it is an antioxidant that plays a role in improving pretty much all major skin concerns: fine lines/wrinkles, congestion, dark spots, dullness, sagging, etc. When retinoids are applied to the skin, they undergo breakdown reactions that transform them into retinoic acid, the actual active that is being utilized. Retinol is one of many Vitamin A derivatives, but it is usually synonymously referred to as Vitamin A simply because it is the most well-known and perhaps oldest form used. In this post, we will be discussing how Vitamin A works on the skin in the form of RETINOIC ACID, which is the molecular form that all retinoids must be converted to once they are applied to the skin to be utilized by the body for active exfoliation.
How do retinoids work?
This is the exciting part. Basically, retinoids are fat/oil-soluble, meaning they are able to penetrate all four-five layers of epidermis. As retinoid begins to penetrate the layers of the epidermis, it comes in contact with a few different types of cells that have receptors located on their cell membranes. When the retinoid binds to the receptor, the cell is activated to conduct a particular function. One of the cell types that retinoids bind with the most affinity to are keratinocytes, (keratin-producing cells), in which the binding of retinoid to the CRBP receptor on the keratinocyte promotes growth (more specifically, proliferation). When keratinocytes proliferate, they produce new, strong skin that can withstand epidermal water loss, collagen degradation, and environmental/antigenic stressors. This is where the basis for retinoids’ “anti-aging” claims come from.
Retinoids travel through both the extra- and intracellular environments, so yes, that means it can even pass through our beloved skin barriers (lipid barriers composed of ceramides, cholesterols, and phospholipids). This allows the ingredient to effectively “loosen” the connective proteins that hold older cells down to each layer and allow new ones to proliferate in their place, essentially resurfacing the skin and promoting a phenomenon commonly referred to as “cell turnover.” Resurfacing in any form usually leads to the clearing of sebum reserves and decongesting of skin overall, which is where some of the “acne clearing” claims of retinoids comes from, but it also leads to the reduction of hyperpigmentation as well. Specifically, retinoids prevent melanin formation and transport when bound to receptors on melanocytes.
What are the different forms of retinoids?
Retinoic acid itself is only available via prescription in the United States. Pure retinoic acid is highly irritating to the skin simply because it is so bioactive. Retinoids (retinoic acid precursors) are available in over-the-counter and cosmeceutical form and will be what we focus on here.
Retinol:
Retinol must first be converted into retinoic acid via a two-step chemical reaction. Retinol is first catalyzed into retinaldehyde by an enzyme, then retinaldehyde is oxidized into retinoic acid. You can find retinol in concentrations anywhere between 0.0015% and 0.3% over the counter.
Retinyl:
Retinyls are esters of retinol and are commonly found as Retinyl Acetate and Retinyl Palmitate in skincare. They are more stable than retinol, but because they have an extra ester bond attached to them, they require an extra step to remove it in their process to develop retinoic acid.
Retinaldehyde:
These are other retinoid derivatives that are found in the intermediate step between retinol and retinoic acid, so they may sometimes be a bit more sensitizing to the skin that retinols. To be converted into retinoic acid, they must be oxidized in an enzyme-catalyzed reaction.
Hydroxypinacolone Retinoate and Retinyl Retinoate:
These are next-generation retinoids that aren’t exactly derivatives of retinoic acid, but just retinoic acid with an ester bond attached to it, so they skip the entire conversion reaction mentioned above. There is not a ton of information available on these ingredients yet, but studies have shown that they do not produce as much irritation as many other retinoids while supposedly working similarly to prescription Tretinoin, so they’re definitely promising ingredients to keep an eye out for.
Bakuchiol:
To be clear, this is NOT a retinoid. It is a naturally derived extract from the Psoralea corylifolia plant that has antioxidant properties that allow it to be considered an alternative to retinoids. The mechanism of action is completely different, but the clearest difference is that bakuchiol is not capable of penetrating the epidermis to the same depth as retinoids. The cool thing about bakuchiol, though, is that you can combine it with retinoids safely.
Combing retinoids with other actives:
Like everything else in the realm of skincare, and well, the world itself, it all boils down to chemistry and physics. We’ll cover our PERSONAL recommendations for combining retinoids with four other main actives in skincare, AHAs, BHA, Vitamin C, and Azelaic Acid below:
AHAs:
Alpha Hydroxy Acids are water-soluble chemical exfoliants, meaning they only conduct surface-level exfoliation, as they cannot penetrate oil the same way retinoids can. Therefore, in theory, AHAs and retinoids should not interact much as one stays on the surface while the other operates within the deeper layers of the skin. However, there is still some interaction between the molecules, of course, since the only way to have them both on the skin is to, well, apply them to the skin. Our advice for safely incorporating AHAs with retinoids is to opt for the molecularly larger AHAs, and our personal favorite is mandelic acid, but lactic acid will work well, too.
BHA:
This is one of the riskier actives to combine with retinoids because salicylic acid (BHA) is oil-soluble as well, and targets the interior of the pore. It is also a keratolytic, so it can loosen the keratin strands that hold cells together the same way retinoids can. The safest way to incorporate BHA with retinoid use is to apply it in a form different from your main retinoid (so if you’re using a retinoid cream or serum, it’s gentler to use a BHA toner or cleanser in the same routine).
Vitamin C:
Contrary to what you might read here and there, Vitamin C and retinoids work well together, just not in the same time of day. When Vitamin C is worn during the day (under an SPF, of course!) and a retinoid is worn at night, skin is well supplemented and protected. You get the best of both ingredients’ brightening and anti-aging properties, but they work with completely different mechanisms so there’s not a whole lot of interference going on.
Azelaic Acid:
This is another active best used during a different time of day than your retinoid. We’re strictly speaking on non-prescription strength Azelaic Acid here (so about a 10% concentration). While AA is a chemical exfoliant, it also works incredibly well for decreasing post-inflammatory erythema and hyperpigmentation (PIE/PIH) as well. We recommend using this ingredient during the day (again, with an SPF!) and applying your retinoid at night.
How to Use a Retinoid:
There’s not a right versus wrong way to use a retinoid, but the most beneficial and safe way to incorporate these powerful ingredients is at night with only one other active at most. In an attempt to keep things simple, we have a basic list of supportive ingredient types to incorporate with retinoids for all skin types, ages, concerns, etc. below:
-Skin Barrier Components: Ceramides, Cholesterols, Phospholipids
-Peptides
-Humectants such as Hyaluronic Acid and Glycerin
-Emollients such as Oat, Oils, Silicones, etc.
-Niacinamide
-Zinc
-Antioxidants
-Allantoin
-Panthenol
-Collagen
-AHAs, BHA, Vitamin C, Azelaic Acid (see above)
-Kojic acid and relatives, such as Diglucosyl Gallic Acid
-SPF—this is NOT optional!
Purging/Peeling:
Purging (seemingly new acne formation) and peeling (dry skin flaking) are the well-known problems with retinoids, as the higher in concentration and potency you go, the greater the risk of purging/peeling. Here’s the thing to remember: purging and peeling are not only normal reactions to incorporating a retinoid, they’re expected. As your retinoid establishes itself deep within the skin and begins to work (usually after anywhere between 3-6 weeks of consistent use), the process of loosening keratin strands and exfoliation begins, allowing dead skin to slough off and congestion located deep within the pore to make its way to the surface. While purging/peeling are uncomfortable and annoying side effects, they are temporary. However, if you experience extended flaking and acneic reactions that outweigh the benefit of the retinoid, it may be wise to discontinue that retinoid. See our post on Purging under Blog Posts.
Pointers for Beginners, Intermediate Users, and Acclimated Users:
Beginners:
-Be sure to start with a low concentration retinoid, even if you’re an experienced AHA/BHA user (we’ve found it best to start with retinyl palmitate, hydroxypinacolone retinoate, and/or bakuchiol for at least three months before diving into a retinol or retinaldehyde).
-Incorporate slowly, perhaps once every 1-3 nights.
-Don’t combine the retinoid with other actives just yet.
-Do combine the retinoid with as many supportive active ingredients as possible (see above list) to prevent sensitivity and irritation.
-Use the same retinoid product for at least six months, as long as it’s meeting your expectations.
Intermediates:
-Slowly increase your retinoid concentration.
-Incorporate a Vitamin C or Azelaic Acid treatment during the day.
-Use the retinoid nightly or every other night.
Acclimated Users:
-Slowly increase your retinoid concentration.
-Incorporate a Vitamin C or Azelaic Acid treatment during the day.
-Incorporate an AHA or BHA at night just prior to retinoid use.
-Combine retinoid with bakuchiol if you choose.
-Use the retinoid nightly or every other night.
Miscellaneous Topics:
Why can’t pregnant women use retinoids?
There is significant evidence that supports the idea that an excess of ingested Vitamin A is harmful to a developing fetus. While there is still a lot of ongoing research about the effects of topical retinoid application on pregnancy, most dermatologists and OBGYNs will agree that the safest bet is to avoid retinoids.
At what age should you start using a retinoid?
We started around the age of twenty, and wouldn’t really recommend it anyone under eighteen as a preventative/supplemental ingredient (obviously, if you’re interested in prescription strength retinoic acid for acne treatment, this is something you need to discuss with your physician), but most experts would agree that it wouldn’t hurt to start incorporating retinoids in your twenties as a preventative and reparative measure.
What is the best form of retinoid to use?
As with all the actives we recommend, a serum form is ideal, but a cream that solely focuses on the retinoid and contains supportive ingredients will work beautifully as well.
Can you use retinoids around the eyes?
Yes, but do be careful with this! Perhaps try a separate, gentler retinoid designed specifically for the eye area rather than just applying your facial retinoid to the eyes.
Sources:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5064676/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6791161/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2699641/