How does salicylic acid help your skin?

Salicylic acid helps your skin by unclogging pores. It is a beta hydroxy acid (BHA) that dissolves in oil, so it can travel into oily pores, loosen the dead skin cells and sebum stuck inside, and help them shed. It also has a mild anti-inflammatory effect on pimples. That combination is why it works best for blackheads, whiteheads and mild acne. Over-the-counter products usually contain 0.5% to 2%, and results take at least 6 to 8 weeks of regular use.

What does salicylic acid do?

Your pores are lined with skin cells that normally shed and leave with the oil your skin makes. In acne-prone skin, those cells stick together and form a plug. Salicylic acid softens keratin, the protein that holds them together, so the plug loosens and pores stay clearer.

• Exfoliates inside the pore. Most exfoliating acids, like glycolic acid, are water-soluble and work mainly on the surface. Salicylic acid is oil-soluble, so it reaches into pores filled with sebum.
• Prevents new clogs. Used regularly, it slows the build-up of cells inside the follicle that leads to new comedones.
• Reduces redness and swelling. It is related to aspirin and has a mild anti-inflammatory effect on pimples.
• Smooths texture. Shedding dead surface cells can make rough or bumpy skin feel smoother.

Salicylic acid for acne and blackheads

Salicylic acid is most useful for comedonal acne: blackheads, whiteheads and small bumps. The American Academy of Dermatology notes that it opens clogged pores and is effective for whiteheads and pimples. If you mostly struggle with blackheads on your nose or oily T-zone congestion, it is often the first ingredient worth trying.

It is less effective on its own for deep, painful nodules or cysts, and it doesn't kill acne bacteria the way benzoyl peroxide does. Many people combine it with other treatments; our guide to what causes acne and which ingredients help explains the options. Whatever you use, expect at least 6 to 8 weeks before you see fewer breakouts.

How much salicylic acid: 0.5% to 2%

Over-the-counter acne products usually contain 0.5% to 2% salicylic acid. A higher number isn't automatically better: 2% leave-on products are more likely to dry or sting than 0.5% to 1%. Stronger salicylic acid peels exist, but they belong in a dermatologist's office.

EU cosmetics rules also cap salicylic acid at 2% in most products (rinse-off hair products such as shampoos can contain a bit more, and some product types less) and restrict it in products for young children. It can also appear at low levels as a preservative.

Cleanser, toner or leave-on: which to choose?

• Cleanser: the gentlest way to start. It's on your skin for less than a minute, so it is less irritating but also less effective. Good for oily or sensitive skin and body acne.
• Toner, serum or gel (leave-on): stays on the skin, so it works better for blackheads. Start with a low strength.
• Spot treatment: useful for occasional pimples, but salicylic acid works best used regularly on the whole area that breaks out.
• Pads: convenient, but easy to overuse. Avoid rubbing hard.

How often should you use salicylic acid?

1. Test a small amount on one or two small areas for 3 days before using a new product.
2. Start with one application every other day, at night.
3. If your skin is fine after 1 to 2 weeks, move to once a day. Some oily skin types tolerate twice daily.
4. Follow with a light moisturizer, and wear sunscreen in the morning.
5. At first, don't layer it with other exfoliating acids, retinoids or benzoyl peroxide in the same routine. If you want both, alternate nights. Our guide to AHA, BHA and PHA acids explains how to combine them.

Salicylic acid side effects

The most common side effects are dryness, peeling, tightness and stinging, especially on broken skin or at higher strengths. Cutting back to every other day and adding moisturizer usually solves it. Avoid the eye area and lips.

Rarely, people have a serious allergic reaction to acne products. Stop and get emergency help for hives, throat tightness, difficulty breathing, or swelling of the face, lips or tongue. Absorbing large amounts through the skin is also rare, but applying high-strength products over big areas of skin isn't a good idea.

Why ingredient scanners flag salicylic acid

If you scan a salicylic acid product, you'll notice the ingredient is tagged Regulated and Preservative. Ingredient scanners, Green Point included, flag salicylic acid because it is a regulated ingredient with concentration limits, and Green Point's ratings are deliberately precautionary. That's about using it safely, not about whether it works.

In practice: a well-made 0.5% to 2% product used as directed is a standard, dermatologist-recommended acne treatment. If you only want smoother texture rather than clearer pores, gentler well-rated options such as lactic or mandelic acid may suit you better.