What retinol does for your skin and how it works

Retinol is a form of vitamin A that is sold in creams, serums and lotions. People buy it for smoother skin, fewer fine lines and a more even tone. This guide explains what retinol is, how the skin turns it into something active, what clinical studies have measured, and who the American Academy of Dermatology (AAD) says it suits. It is part of Skinli's guide to retinoids for acne, and it is general education. A dermatologist can advise on your own skin.

What retinol is

MedlinePlus, the U.S. National Library of Medicine's health site, says vitamin A "is also known as retinol because it produces the pigments in the retina of the eye." It calls preformed retinol an active form of vitamin A, found in animal liver, whole milk and some fortified foods. Vitamin A is fat soluble and is stored in the liver. Retinol in a cream is meant to stay on the skin. MedlinePlus warns that swallowing products with vitamin A, "such as skin cream with retinol in it," can cause vitamin A poisoning, and that babies and children are more sensitive to vitamin A than adults. Keep retinol products where children cannot reach them.

In skin care, retinol belongs to a larger family. The AAD says the term retinoids "is a catch-all for an array of vitamin A-based products used on skin." Inside that family, the AAD describes retinol as "a type of retinoid that's routinely used to improve uneven skin tone, pigmentation, and texture," available over the counter in many products. The acne medicines adapalene, tretinoin, tazarotene and trifarotene belong to the same family. Skinli's guide to retinol vs retinoid explains how the names relate.

Retinol is sold as a cosmetic ingredient. That has one practical effect you can see on the shelf. The AAD points out that "there's no standard requirement that the percentage of retinol be disclosed on the label or packaging."

How retinol works in the skin

Retinol has to be changed by the skin before it acts. A 2022 review in the journal Advances in Therapy describes the steps: "retinol is converted to biologically active retinoic acid (tretinoin) via retinaldehyde by dehydrogenases in a two-step oxidation process." Dehydrogenases are enzymes in the skin. Retinoic acid is the same substance as the prescription medicine tretinoin.

That conversion explains why the retinoids differ in strength. The review ranks them by activity. Retinyl esters are the weakest, then retinol, then retinaldehyde, and retinoic acid is the strongest. It says the ranking for how well skin tolerates them runs the other way. The same review estimates that retinol is ten times less potent than tretinoin.

Form	What it is	How it is sold
Retinyl esters, such as retinyl palmitate	Storage forms that skin turns into retinol	Cosmetic products
Retinol	Vitamin A itself	Cosmetic products
Retinaldehyde (retinal)	The middle step	Cosmetic products
Retinoic acid (tretinoin)	The active form	Prescription medicine

Once active, retinoids act on the skin cells themselves. The AAD says a retinoid "spurs faster turnover of surface skin cells and boosts collagen." Collagen is one of the proteins that make up skin. The AAD's page on skin care in your 20s says retinol can give "younger-looking skin by speeding up new skin cell turnover, which starts to slow in your 20s." The 2022 review lists more effects of retinol on sun-damaged skin, including increased production of hyaluronic acid, collagen and elastin.

What studies have measured

Three studies give a picture of what retinol changes. Each one is small, with 36 to 62 people, so the results describe groups and may differ for you.

A 2007 trial at the University of Michigan tested 0.4 percent retinol lotion in 36 older adults with an average age of 87. Study staff applied the lotion to one arm and the same lotion without retinol to the other, up to 3 times a week for 24 weeks. Fine wrinkling improved on the retinol arm. Skin samples from a small subgroup showed more collagen and more glycosaminoglycan, a substance that holds water in the skin.

A 2016 study, run by researchers at a skin care company and a university, compared retinol with retinoic acid. After 4 weeks both had thickened the outer layer of the skin and raised collagen genes. The authors wrote that retinol "induces similar changes" to retinoic acid, and that "the magnitude tends to be smaller." Photos showed fewer facial wrinkles after 12 weeks of retinol.

A 2015 trial followed 62 people who used 0.1 percent retinol or the same product without it on the whole face for 52 weeks. The retinol group improved more than the comparison group at every visit, and at week 52 the authors reported improvement in fine lines at the corners of the eyes and in blotchy pigmentation.

The 2022 review adds a warning about these studies. It says there is "a lack of evidence from properly designed clinical trials" for the retinoids used in cosmetics, and that sponsored studies and the wide range of strengths make it questionable whether positive results reflect the ingredient itself. Skinli's guide to retinol before and after sets out the timelines from these studies week by week.

What the AAD says retinol is good for

The AAD names several uses:

• Tone, dark spots and texture. Its page on skin care in your 20s says to look for the word retinol if you want to treat uneven skin tone, dark spots or your skin's texture.
• Mild fine lines. It says a retinoid product "is a good option for someone with mild acne, mild pigmentation irregularities, or mild fine lines and wrinkles."
• Large-looking pores. Its pores page says a product with retinol or retinyl palmitate may help when skin is oily or less firm than it once was.
• Early stretch marks. Its stretch marks page says retinol, another type of retinoid, may also help fade early stretch marks.
• Mild acne. One AAD page for darker skin tones lists retinol for mild acne and says it "can unclog pores and fade dark spots."

Acne is where the evidence for retinol is thinnest. The guidelines doctors use for acne name adapalene, tretinoin, tazarotene and trifarotene, and Skinli's guide to whether retinol works for acne sets out what is known. For dark marks left after pimples, see Skinli's guide to fading dark marks after pimples.

Who it suits, and who should ask first

The AAD's advice on who should hold off is specific. It says "people who have skin allergies or dryness are probably not good candidates for a product that contains a retinoid." A dermatologist quoted on the same page says people with a lot of redness or inflammation should avoid retinoids and ask about rosacea treatments, and that people with moderate or severe acne scarring, or acne tied to periods or other hormone changes, should see a board-certified dermatologist before trying a retinoid. The AAD also says retinoids should not be used during pregnancy. Skinli's guide to retinoids during pregnancy and breastfeeding covers what each source says.

People with darker skin have one more thing to watch. An AAD dermatologist says, "With skin of color, irritation can trigger dark marks, known as hyperpigmentation," and adds that starting slowly and using moisturizer helps.

How long a retinol product keeps

Retinol breaks down. The 2022 review says retinol is sensitive to "light, oxygen, heat, and heavy metals," and that retinol in cosmetics is generally stable for less than 6 months even when it is made without air and stored in aluminum tubes at 20 °C or below.

Most retinol products are cosmetics, and the FDA says "there are no U.S. laws or regulations that require cosmetics to have specific shelf lives or have expiration dates on their labels." Drugs are different: they must be tested for stability and carry an expiration date. The FDA's advice for cosmetics is to keep them away from heat, such as a hot car, because temperature, sunlight and air can change their color, texture and smell. For the prescription retinoid tretinoin, MedlinePlus gives similar storage advice: room temperature, away from excess heat and moisture, and not in the bathroom. A retinol product that has changed color or smell has changed in some way, and no source read for this guide says it still works as it did.

Using it carefully

Retinoids can irritate, and they make skin more sensitive to the sun. The AAD says some ingredients, "such as retinol and glycolic acid, can irritate your skin, particularly if your skin is sensitive," and calls that reaction normal and temporary. It advises the least intense product you can find, used every other night at first and slowly built up, applied at night, with sunscreen and sun protection during the day. Skinli's guide to starting retinol without irritation gives the steps, and its guide to whether retinol is bad for you covers side effects and safety in full.

If a new product causes a reaction, the AAD says to wash it off gently as soon as possible and not use it again, and to see a dermatologist if the reaction is severe.