Salicylic acid
Loosens and lifts scale in anti-dandruff shampoos and scalp treatments Also on labels as: BHA, beta hydroxy acid
Reviewed on
What it does
Salicylic acid is a keratolytic — it loosens the bonds between skin cells so scale can lift and wash away. It's one of the three ingredients the NHS suggests looking for in an anti-dandruff shampoo, and dermatologists use it in descaling treatments for thick scale in seborrhoeic dermatitis and scalp psoriasis, so that other treatments can reach the skin.
It turns up in two forms:
- Cosmetic shampoos and scalp serums, where UK rules cap the amount (see below).
- Medicines, often combined with coal tar, coconut oil or sulphur, such as scalp ointments that are left on for an hour or more before washing out.
Cautions
- It can irritate and dry the skin (NICE, BAD).
- NICE says medicines containing salicylic acid shouldn't be used by people who are allergic to aspirin, or on broken or inflamed skin, and shouldn't be applied to large areas of the body. Take care in pregnancy and breastfeeding and if you have diabetes — ask a pharmacist.
- UK cosmetic rules say salicylic acid products must not be used for children under 3.
How strong is the evidence?
Evidence: Limited
Small or early studies only — promising at best.
Salicylic acid is recommended by the NHS and dermatologists for scaling, but trial evidence for it on its own is thin. In a small 1987 trial, a shampoo combining 2% salicylic acid with 2% sulphur reduced scaling more than either ingredient alone or the plain shampoo base; salicylic acid by itself didn't clearly beat the base. Other studies test it in combination with anti-dandruff actives.
UK rules and availability
Allowed in cosmetics in Great Britain with limits — up to 3% in rinse-off hair products and 2% in most other products — and not for use in products for children under 3. Higher-strength and combination products are sold as medicines.
Products on this site that list it
- Dermal Capasal Therapeutic Shampoo
- Nioxin System 1 Shampoo (Scalp + Hair Thickening System 1 Cleanser)
- The INKEY List Salicylic Acid Exfoliating Scalp Treatment
- Sebco Scalp Ointment
- Philip Kingsley Flaky/Itchy Scalp Mask (2 x 20ml)
Not medical advice. This guide is general information from the sources listed, not a diagnosis or a substitute for a pharmacist, GP or dermatologist. If you are worried, or symptoms are severe or not improving, get advice. Read our health information policy.
Sources
- NHS – Dandruff nhs.uk
- British Association of Dermatologists – Seborrhoeic dermatitis bad.org.uk
- British Association of Dermatologists – Psoriasis: topical treatments bad.org.uk
- NICE CKS – Salicylic acid (psoriasis) cks.nice.org.uk
- legislation.gov.uk – Cosmetics Regulation Annex III (restricted substances) legislation.gov.uk
- Ranganathan S, Mukhopadhyay T. Dandruff: the most commercially exploited skin disease. Indian J Dermatol 2010 pmc.ncbi.nlm.nih.gov
- Leyden JJ et al. Cutis 1987 pubmed.ncbi.nlm.nih.gov