Exfoliating acids show up on a lot of best-selling products, usually as "AHA" or "BHA" — and the difference is worth understanding, because it changes which one suits your skin. Here is what BHA is, how it compares to AHA, and how to use either without overdoing it.
What is BHA?
BHA stands for beta hydroxy acid, and the most common one is salicylic acid. It is oil-soluble, which means it can work into the pore lining, so it is often chosen for oily, congestion-prone, or blackhead-prone skin. In products it is used to help the look of clearer, smoother skin over time.
What is the difference between AHA and BHA?
The short version: AHAs (like glycolic, lactic, and mandelic acid) are water-soluble and work on the surface, helping with tone and texture; BHA is oil-soluble and gets into pores, so it leans toward congestion and oiliness. AHAs are a common starting point for dullness and rough texture, while BHA is popular for breakout-prone, oily skin. Neither is "better" — they suit different concerns.
Which acid should you choose?
Match it to your skin:
- Oily or congestion-prone: BHA (salicylic acid) is a common pick.
- Dull or rough texture: an AHA like glycolic or lactic acid; the gentlest AHA for beginners is a softer start.
- Sensitive skin: start with a lower strength, less often, whichever type you choose.
How do you use an exfoliating acid gently?
Start low and slow — a couple of times a week — and build up only if your skin stays comfortable. Follow with a moisturizer and always wear daily SPF, since acids can make skin more sensitive to the sun. Avoid stacking several strong actives at once, and if you see stinging or redness, ease off; our guide on how often to exfoliate has more. Over-exfoliation is a common cause of irritation, so less is usually more.
AHA vs BHA FAQ
What is BHA in skincare?
BHA is beta hydroxy acid, most commonly salicylic acid. It is oil-soluble, so it can work into pores, which is why it is popular for oily, congestion-prone skin.
What is the difference between AHA and BHA?
AHAs are water-soluble and work on the surface for tone and texture, while BHA is oil-soluble and gets into pores for oiliness and congestion. They suit different concerns rather than one being better.
Can you use AHA and BHA together?
Some products combine them, but using several strong acids at once can irritate sensitive skin. If you are new to acids, start with one, used gently, before combining.
Is BHA good for sensitive skin?
BHA can suit sensitive, oily skin at a low strength used infrequently, but tolerance varies. Patch test, start slow, and follow with moisturizer and SPF.
Do you need sunscreen when using acids?
Yes — exfoliating acids can make skin more sensitive to the sun, so daily SPF matters. It protects your skin while you use the acid and is a good habit regardless.
Pick the acid for your skin
BHA suits oil and congestion, AHA suits tone and texture, and the right one depends on your skin, not the trend. Start low, moisturize, wear SPF, and ease off at the first sign of irritation.
