The Ultimate Guide To Understanding The Hierarchy of Retinoids

Not many skin care ingredients are as highly regarded by dermatologists and estheticians as retinol, or more specifically, retinoids. Most skin care professionals will tell you to start using these vitamin A derivatives by the time you hit your mid-twenties, as they address a range of skin concerns and can be beneficial for most people, whether you’re fighting persistent acne or looking to delay the tell-tale signs of aging like dark spots, fine lines, crepey skin and more. Available in many forms, retinoids range from potent prescription medications to over-the-counter skin care products you can snag at the drugstore or your favorite high-end beauty haunt. And contrary to popular belief, there are plenty of options out there that are gentle enough for those with sensitive skin.

Because “retinoid” is essentially a blanket term for the many derivatives of vitamin A (which are derived from animal sources), it’s easy to be confused by all the terminology that’s out there. What’s the difference between retinol and retinaldehyde (also known as retinal)? What the hell is trifarotene? Don’t worry, your guide to understanding the hierarchy of retinoids — and finding the right one for your skin’s specific needs — awaits below. Plus, you’ll learn about the most popular vegan alternatives to vitamin A products. But first, the basics.

The Hierarchy of Retinoids: How Do They Work?

Retinoids are broken down into four main categories: retinyl esters, retinol, retinaldehyde, and retinoic acid. The first three are available as over-the-counter skin care products while retionic acid is only available in prescription form. They all work by binding to and activating retinoic acid receptors in the skin, which, according to board-certified dermatologist Dr. Corey L. Hartman, alter the skin’s DNA makeup, thus changing its appearance and texture, leading to varying benefits like improvements in pigmentation, the appearance of fine lines and wrinkles, and minimizing acne.

But here’s the deal: No matter what type of retinoid you apply topically, your skin can only use its most biologically active form, which is retinoic acid. Retinyl esters, retinol, and retinaldehyde all need to first convert to retinoic acid directly on the skin’s surface in order for your skin to reap the benefits, and the more steps it takes to convert, the weaker (and therefore gentler) it will be — but more on that, later.

“[Retinoids] exist on an inverted scale between efficacy and irritability,” says board-certified dermatologist Dr. Elyse Love. “Of the over-the-counters, retinyl esters are the least potent and most stable, retinol is the in-between, and retinaldehyde (retinal) is the most potent, but most difficult to stabilize.” Their potency also correlates to the level of irritation users may experience, though a product’s formulation and retinoid concentration are also factors that affect this.

You might be curious as to whether some retinoids are more costly than others — the higher the strength, the higher the price tag, right? Wrong. The truth is, all forms of retinoids — both over-the-counter and prescription — range in price. “Prices vary for retinoids, especially for prescriptions, based on insurance coverage,” says Dr. Hartman. “Many effective OTC retinols are available at your local drugstore at a lower price point, but you can also shop high-end retinol products for hundreds of dollars.”

This holds true for the other forms of retinoids too, and pricing doesn’t have anything to do with strength. Retinyl ester products aren't necessarily less expensive than retinols, nor will retinaldehyde (retinal) products necessarily be pricier than retinols. As board-certified dermatologist Dr. Morgan Rabach adds, a steeper price tag doesn’t necessarily equate to a higher quality product, either. “It’s mostly about branding and positioning of the product in the market, and not about quality of ingredient,” she says. With that said, it is possible to shop for the right retinoid for your specific skin needs, no matter your budget.

So how do you determine which retinoid form is right for you? Up first: over-the-counter options.

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The Hierarchy of Retinoids: Over-the-Counter Retinoids

Retinyl Esters

Retinoids are commonly thought to lead to red and irritated skin, but luckily there are options that provide all the benefits without the harsher side effects. Case in point? Retinyl esters. The least potent form of retinoids, it takes retinyl esters three steps to convert into retinoic acid on the skin — first converting to retinol and then retinaldehyde before becoming active. This means that these derivatives of vitamin A — which include retinyl palmitate, retinyl linoleate, retinyl acetate, and retinyl propionate — are quite gentle.

“Products with retinyl esters are great for first-time [retinoid] users or people with very sensitive skin,” says Dr. Hartman. He points out that, while they may be the weakest form of a retinoid, with consistent use, they can still help address a number of skin concerns like lines and wrinkles, uneven texture and tone, and even milder forms of acne.

Retinol

Arguably the most popular form of retinoids is retinol, which is famed for its many anti-aging and skin-renewing abilities. “The benefits of retinols are numerous and unparalleled, and [using them is] arguably the most important step that you can take for overall skin health and anti-aging after sun protection,” says Dr. Hartman. “They regulate cell turnover, promote effective exfoliation, prevent acne, even discoloration, control oil, smooth fine lines and wrinkles, unclog pores, and so much more.”

Retinol takes two steps to convert into retinoic acid, converting first into retinaldehyde, deeming it more effective than retinyl esters. However, board-certified dermatologist Dr. Rina Allawh points out that it’s notorious for being irritating, drying, and causing the skin to peel, which can be drawbacks for those with more sensitive skin. Because it can take some time for the skin to become acclimated to retinol, sensitive or not, she suggests building up tolerance slowly. “Some tricks of the trade include shorter contact time (such as applying at dinner and washing off at bedtime), mixing with a nighttime non-comedogenic moisturizer, and starting use at one-to-two nights weekly and increasing to nightly as tolerated,” she says.

Retinaldehyde

Retinaldehyde, also known as “retinal” — not to be confused with retinol — is the strongest of the over-the-counter retinoids. One step closer to retinoic acid on the conversion scale, it only takes one step for it to convert and become active, making it more potent than the aforementioned retinyl esters and retinol. “Similar to retinol, retinals help promote cell turnover to even skin tone and texture, smooth wrinkles and fine lines, and prevent acne,” says Dr. Hartman. Also similar to retinol is the irritation and dryness you may experience while using it; however, you can expect it to still be gentler than pure retinoic acid.

Retinoic Acid Esters

A relatively new form of retinoids that are thought to fall somewhere between retinol and retinoic acid on the efficacy and irritation scale are retinoic acid esters. Here’s the cool thing: even though they’re quite effective at combatting a wide range of skin concerns, they’ve been shown to be pretty gentle. “Although they are relatively new compounds, they show promise for being more active than retinol, without the irritation,” says Dr. Hartman. “They’ve been proven in study after study to encourage cell turnover, stimulate collagen, help treat acne, soften wrinkles, fade pigmentation, and give the skin an overall youthful glow.”

The two forms of retinoic acid esters are retinyl retinoate and hydroxypinacolone retinoate (HPR), which is more popularly known as granactive retinoid. Unlike other forms of retinoids, retinyl retinoate converts into both retinoic acid and retinol when it interacts with the skin, meaning it offers both instant and delayed benefits as the retinol begins its own two-step conversion process. HPR binds directly to retinoid receptors without having to be converted to retinoic acid.

Adapalene

Adapalene is a synthetic retinoid derived from napthoic acid that does not need to be converted to retinoic acid before it becomes active. It’s available both over-the-counter and in prescription form, and the few OTC products on the market are all very reasonably priced.

As Dr. Hartman explains, adapalene regulates cell turnover and decreases inflammation, which is why it’s become a superstar ingredient for treating acne. “It prevents new acne from forming, and like other retinols, helps to even skin texture and tone while reducing the inflammation and redness caused by acne,” he says. Dr. Allawh also mentions that more recently, adapalene has been implemented in anti-aging topicals for its treatment of dark spots and fine lines and wrinkles.

Over-the-counter adapalene (which contains a 0.1% concentration) is considered the first treatment to contain a prescription-strength acne-fighting retinoid, and out of all the prescription retinoids available, it’s considered the weakest (and therefore, gentlest). For this reason, it makes for a great entry product for anyone with sensitive or acne-prone skin. “And if the OTC version doesn’t produce the results you’re looking for, you can see a dermatologist to determine if a prescription version of a higher concentration would be better to treat your specific needs,” adds Dr. Hartman.

The Hierarchy of Retinoids: Prescription Retinoids

Retinoic Acid

As mentioned earlier, retinoic acid is the most potent form of retinoids. “This is the end point molecule that is biologically active on skin, and is therefore the strongest,” says Dr. Rabach. Because it’s already active and doesn’t need to be converted on the skin, it begins to work its cellular renewal and repair magic right away. However, that means stronger side effects than its weaker counterparts (think: dryness, peeling, and irritation) are also usually part of the deal. Due to its strength, you can only get retinoic acid treatments via a prescription, which are typically issued when gentler over-the-counter treatments haven't been successful.

Retinoic acid treatments can address more severe skin conditions like cystic acne in addition to signs of aging, hyperpigmentation, and melasma. “They reduce fine lines and wrinkles by increasing the production of collagen,” says Dr. Hartman. “They also stimulate the production of new blood vessels in the skin, which improves skin [tone]. Additional benefits include fading age spots and softening rough patches of the skin.”

Tretinoin and isotretinoin are the two prescription forms of pure retinoic acid, however there are a few other prescription retinoid treatments available in addition to the aforementioned adapalene. Below, a deeper dive into each.

Tretinoin

Commonly known as Retin-A, tretinoin is a topical form of pure retinoic acid, meaning that it’s already active and does not need to be converted on the skin. “It’s one of the most popular forms of vitamin A to use topically, and one of the most researched forms to date, given its positive effects on photo-aging and acne,” says Dr. Allawh. “It’s used to treat comedonal acne, even out skin pigmentation such as melasma and post-inflammatory hyperpigmentation, and is used as a non-invasive treatment for fine lines and wrinkles.”

Since tretinoin is pure retinoic acid, Dr. Hartman explains that it’s one of the more powerful prescription retinoids — but that also means it comes with side effects. “When you start using it, expect to see mild flaking, dry patches, mild redness, and perhaps a purge of acne legions,” he says. “Going slowly with the application of the product (two-to-three timers per week instead of every day) and applying it in conjunction with a non-comedogenic moisturizer can help to acclimate the skin to the product more quickly and easily.”

Isotretinoin

Isotretinoin, commonly known as Accutane, is the oral form of retinoic acid and the most potent of all retinoids — thus, it’s often reserved for more severe and resistant forms of acne. “When taken orally, it permanently reduces oil gland size and oil gland production,” says Dr. Rabach. Since it’s a much more intense medication, its side effects include dry skin, eyes, nose, and lips, and muscle aches. “Bloodwork is checked monthly to make sure the patient is tolerating the medication,” she says.

Side effects aside, it can provide some pretty powerful results. “Isotretinoin is the only acne treatment that has long-term beneficial effects on the skin,” says Dr. Hartman. “Statistics show that 70% of people treated with it will have clear skin for life. The other 30% may have some acne again, but it’s usually less severe than before.” He goes on to say that when low doses are taken over a longer treatment time, it can provide a long-term cure for acne with minimal discomfort.

Trifarotene

A newer prescription retinoid used for acne treatment is trifarotene, which Dr. Hartman says is unique due to it being the only topical retinoid that selectively targets the gamma retinoic acid receptor, which is the most common retinoic acid receptor found in the skin. “It’s been shown to remove dead skin cells, unclog pores, and help prevent new acne from forming,” he says.

If adapalene hasn’t been working for you, consider this one the next step up: “It’s stronger than other retinoids with a lower risk of irritation — it’s more potent than adapalene, but less potent than tretinoin,” he says. Dr. Rabach mentions that trifarotene is also a great option for addressing acne that covers larger areas of the body. “Because of the specificity of the receptor, trifarotene is the only retinoid that’s FDA approved for large surface areas of the skin, including the chest, shoulders, and back — it’s fairly gentle,” she says.

Tazarotene

The strongest of topical retinoids is tazarotene (also known as Tazorac), a retinoid that binds to both the beta and gamma retinoic acid receptors in the skin. It’s used to address concerns such as acne, psoriasis, and photo damage of the skin. “It works to treat acne and psoriasis by slowing skin cell overgrowth and decreasing skin cell inflammation, which can lead to these [concerns],” explains Dr. Hartman. “It’s also been shown to tighten skin, even out pigmentation, and smooth fine lines.” According to Dr. Allawh, tazarotene can be especially drying — even more so than tretinoin. It’s available in various formulations such as creams, foams, and gels, gels being the most irritating.

The Hierarchy of Retinoids: Retinoid Alternatives

Now, in addition to the many forms of retinoids, there are a number of plant-based alternatives (also known as “retin-alts”) that provide benefits similar to retinoids while being much gentler — though, not quite as efficacious. These can be worth exploring if your skin can’t tolerate any of the above over-the-counter retinoids.

“Retin-alts have been increasingly popular in the cosmetic and skin-care industry,” says Dr. Allawh. “These natural alternatives can treat acne, improve skin texture, and provide anti-aging benefits.” These include bakuchiol, resveratrol, carrot oil and carotenoids such as astaxanthin, and cacay oil, a nut-derived form of vitamin A.

Without question, the most popular of the retin-alts is bakuchiol, which has become quite a buzzy skin care ingredient over the past couple of years.

Bakuchiol

Bakuchiol is a natural, vegan ingredient that is derived from the Psoralea corylifolia plant, a plant that, as Dr. Hartman points out, has been used throughout history in traditional Ayurvedic and Chinese medicine. “Bakuchiol has antioxidant and anti-inflammatory properties similar to retinol, which makes it a great alternative to treat signs of aging like fine lines, wrinkles, and uneven tone,” he says. “It can also increase skin firmness and reduces the appearance of pores.”

The wonderful thing about bakuchiol is that, while it provides all of these amazing benefits, it’s significantly gentler than your average retinol product. “It's great for people who are new to retinol, or have tried retinol in the past but found they cannot tolerate it,” he says. And unlike retinoids, Dr. Love mentions that bakuchiol is also considered safe during pregnancy and breastfeeding, “although no clinical studies have been performed in pregnant or breastfeeding women.”

So, if you’re thinking about trying out a new retinoid product, but assume your only option is the standard retinol — or if you haven’t seen the results you’re looking for out of your current retinoid product — don’t be afraid to try one of the above options. And when in doubt, consult a trusted dermatologist for guidance. They’ll be able to steer you towards the clear, healthy skin you’ve always wanted.