Glossary

BHA (Beta Hydroxy Acid)

Written by Reviewed by the SYNC editorial team Published Last reviewed Editorial standards

BHA (Beta Hydroxy Acid) — an oil-soluble exfoliating acid best known for its ability to penetrate into pores and dissolve excess oil and debris. Salicylic acid is the most common example and is frequently used in products aimed at oily, congested, or blemish-prone skin.

Key points

  • Because BHAs are oil-soluble, they can work inside pores as well as on the skin's surface.
  • Salicylic acid is the most widely used BHA and is often included in products for acne and blackheads.
  • BHAs can have soothing properties and are sometimes chosen for skin prone to redness or congestion.
  • As with other chemical exfoliants, sunscreen use is generally recommended to protect exfoliated skin.

Frequently asked

Why are BHAs good for oily skin?

BHAs are oil-soluble, so they can penetrate into pores and help clear excess oil and debris that contribute to congestion. This makes them a common choice for oily and blemish-prone skin.

Can I use a BHA and an AHA together?

Some products combine them, but using both can increase the risk of irritation for sensitive skin. Introducing one at a time and monitoring tolerance is a cautious approach.

Related topics

This is a foundational entry in the SYNC Skin Encyclopedia and is expanded over time. Educational information only — not medical advice.

Encyclopedia

Further reading

This entry was written and checked against the sources below. They are published by clinical and scientific bodies, they are listed most readable first, and each one opens in a new tab. They are background for the whole entry rather than footnotes to individual sentences.

  1. Salicylic acid DermNet NZ Clinical guidance dermnetnz.org
  2. Keratolytic agents DermNet NZ Clinical guidance dermnetnz.org
  3. Salicylic acid as a peeling agent: a comprehensive review PubMed Central Peer-reviewed, open access pmc.ncbi.nlm.nih.gov
  4. Applications of hydroxy acids: classification, mechanisms, and photoactivity PubMed Central Peer-reviewed, open access pmc.ncbi.nlm.nih.gov
  5. A review of toxicity from topical salicylic acid preparations PubMed Peer-reviewed (abstract) pubmed.ncbi.nlm.nih.gov
  6. Efficacy and Consumer Perception of Topical Over-the-Counter Regimens Involving Beta-Hydroxy Acid for Acne Vulgaris PubMed Peer-reviewed (abstract) pubmed.ncbi.nlm.nih.gov

SYNC does not publish medical advice. Nothing here replaces a consultation with a doctor or a pharmacist about your own skin.