Acne serums: how to read the label first

An acne serum is a thin, liquid product sold for acne. The word serum describes the texture. What decides whether a serum treats acne is its active ingredient and the strength of that ingredient. This guide shows how to check both, how to fit a serum into a routine, and when a serum is the wrong choice. For the bigger picture, see how to get rid of acne.

Serum is a texture, and the ingredient does the work

The FDA says a product's intended use decides whether it is a drug or a cosmetic. A product that claims to treat acne is a drug, and it has to follow the FDA's rule for acne medicines, called the acne monograph. That rule allows these active ingredients, at these strengths:

Active ingredient	Strength the FDA allows
Benzoyl peroxide	2.5 to 10 percent
Salicylic acid	0.5 to 2 percent
Sulfur	3 to 10 percent
Sulfur with resorcinol	3 to 8 percent sulfur with 2 percent resorcinol

Every over-the-counter drug must carry a Drug Facts box, and the active ingredient and its percentage are printed there. The monograph names cream, gel, lotion and ointment as examples of forms, and it allows other forms too. A serum can be any of these ingredients in a thin liquid.

If a serum has no Drug Facts box and no active ingredient, it is sold as a cosmetic. Serums built around ingredients such as niacinamide or vitamin C are outside this guide.

What to check on the bottle

Read three things before you buy.

1. The active ingredient and its strength. Look for it in the Drug Facts box. For benzoyl peroxide, the American Academy of Dermatology (AAD) says it is best to start with 2.5 percent. For salicylic acid, a low percentage inside the 0.5 to 2 percent range is a gentle start.
2. A pore-safe label. The AAD asks people with acne to check every product for one of these terms: non-comedogenic, non-acnegenic, oil-free, or won't clog pores. NIAMS, part of the US National Institutes of Health, explains that noncomedogenic means the product does not clog pores. NICE, which writes clinical guidance for England, also advises avoiding oil-based and comedogenic skin products.
3. Irritants. The AAD warns that astringents, toners and exfoliants can irritate acne-prone skin and make acne appear worse, and it suggests products that say alcohol-free.

Which serum ingredient fits which acne

Each active ingredient suits a different type of breakout.

• Salicylic acid unclogs pores and exfoliates the skin. The AAD says it works best on whiteheads and blackheads. The 2024 AAD guideline gives it a conditional recommendation, which is one step below its strongest rating.
• Benzoyl peroxide reduces the bacteria that make acne red. It carries the guideline's strongest rating. It also bleaches hair and fabric, so a benzoyl peroxide serum needs the same care as a gel.
• Azelaic acid opens clogged pores, works on acne bacteria and calms inflammation, according to the AAD. It can also fade the dark spots acne leaves. The guideline rates it conditional.
• Adapalene is a retinoid sold as a 0.1 percent gel without a prescription. It carries the guideline's strongest rating. It is usually sold as a gel, and its label says it is not a spot treatment.

Salicylic acid vs benzoyl peroxide helps you choose between the two most common serum ingredients.

Serum, gel, cream or wash

A thin serum can feel lighter than a cream. NIAMS says acne medicines you put on the skin come in many forms, including gels, lotions, creams, soaps and pads, and that any of them can cause irritation, burning or redness in some people. The AAD says the same about benzoyl peroxide, which is sold in cleansing bars, washes, gels and creams.

The bigger split is between products that stay on the skin and products you rinse off. The FDA rule has separate directions for each, and it names soaps and masks as examples of products that are applied and then removed. A serum is a leave-on product, so it stays in contact with the skin until your next wash. For red pimples and pus-filled spots, the AAD suggests a wash with benzoyl peroxide or salicylic acid. For blackheads and whiteheads, it suggests a retinoid, and adds a benzoyl peroxide wash.

Choose the form your skin can put up with every day for 12 weeks, because a treatment only works while you keep using it.

How to use an acne serum

An acne serum with an active ingredient follows the same directions as any monograph acne product. The FDA requires these on every label:

1. Clean the skin well before applying.
2. Cover the entire affected area with a thin layer.
3. Start with one application a day, then increase to two or three times a day only if needed.
4. If dryness or peeling bothers you, cut back to once a day or every other day.

The AAD adds that acne medicine works best spread in a thin layer over all acne-prone skin. If you break out on your forehead, nose and chin, the serum goes evenly on all three areas. That treats the acne you have and helps prevent the next breakout.

On timing, the label decides. The AAD says dermatologists often recommend applying a topical retinoid in the evening. Many people keep all their acne treatments at night and keep the morning for cleanser, moisturizer and sunscreen. What order to apply your acne products covers where a serum sits among your other steps.

Do not stack acne serums

It is easy to own three or four acne products at once: a salicylic acid serum, a benzoyl peroxide gel, a retinol cream, an acid toner. The FDA requires every acne medicine to warn that skin irritation and dryness are more likely if you use another topical acne medication at the same time, and to use only one at a time if irritation happens.

The AAD gives the same advice from another angle. Trying too many products can stress your skin and worsen acne, so try one or two products and give them time to work. Its advice for adults treating acne at home is to use one product for 6 to 8 weeks, without adding another and without stopping the first.

If you already use a retinoid, such as adapalene or retinol, adding an acid serum on top raises the chance of redness and peeling. What to mix with a retinoid goes through the common pairs.

When a serum is the wrong choice

A serum is a surface product. The AAD says large, painful pimples that sit deep in the skin, and acne that leaves a scar when it clears, need a dermatologist, because products you can buy in a store are unlikely to treat them. No serum format changes that.

A serum is also the wrong choice when your skin is already irritated. Stinging, burning or peeling means the skin needs fewer products for a while. Skinli's own advice when a product stings or peels is to stop it, go back to face wash, moisturizer and sunscreen for a week, and then try again more slowly.

Serums sold for acne marks

Some serums are sold to fade the marks acne leaves. A flat red, pink or brown mark is a different problem from a pimple. The AAD says these flat spots are not scars, that they usually fade over time, and that treatment can clear them more quickly. It names azelaic acid as an acne treatment that can also fade dark spots. Dents and raised scars are a separate problem again, and the AAD lists dermatologist procedures for them. How to get rid of acne scars explains which marks need a dermatologist.

Where a serum fits in Skinli's plan

Skinli's plan uses two gels at night: adapalene 0.1 percent and benzoyl peroxide 2.5 percent. If you want to use a salicylic acid serum as well, treat it as a change to the plan and add nothing else at the same time. Skinli's lessons say to add one cream at a time and wait two or three weeks before adding the next, and the adapalene lesson says not to use salicylic acid at the same time as the acne gel, because the label warns against using several acne medicines together.

How long to give it

The same timeline applies to a serum as to any acne treatment. The AAD says to use a product for 6 to 8 weeks to see some improvement, and that complete clearing generally takes 3 to 4 months. NICE builds treatment in 12-week courses. If a serum with a proper active ingredient has not helped after that time, the next step is a treatment with stronger evidence, such as benzoyl peroxide or adapalene, or a visit to a doctor. The best acne treatments by guideline sets out the options.