What is the difference between AHA and BHA?

How do AHA and BHA compare?

The distinction is not absolute. Salicylic acid also improves skin texture and colour, and glycolic acid can help acne prone skin. Both are exfoliants: they help shed dead skin rather than adding moisture alone.36

Which should you choose?

Choose the acid for the problem you want to address, not to complete a bathroom alphabet collection.1

• For blackheads and whiteheads, choose salicylic acid. It gets into oily pore openings and helps clear the material blocking them.
• For roughness with sensitive skin, consider lactic acid. It is a gentler AHA that acts as both an exfoliant and a moisturizer.
• For fine lines and uneven pigmentation, consider glycolic acid. It smooths the surface but can be strong and irritating, so start slowly.
• For pores that look larger because they are clogged, salicylic acid can help make them less noticeable. Irritation and scrubbing can make pores look more noticeable instead.

How should you start using them?

1. 1Pick one product for your main concern. For acne, use it as directed for 6 to 8 weeks without adding another acne treatment.
2. 2Start glycolic acid once or twice a week at night. Increase frequency only if your skin tolerates it. For a starting AHA product, keep the concentration no higher than 10% to 15%; that is a ceiling, not a target.
3. 3Follow the product's application instructions. AHA products include both leave on preparations and treatments that must be rinsed off. For an acne medication, apply a thin layer across the acne prone area rather than only visible spots.
4. 4If a salicylic acid cleanser dries or irritates your skin, alternate it with a gentle cleanser: use the gentle cleanser in the morning and salicylic acid before bed.
5. 5Use sunscreen with SPF 30 or higher every day. With AHAs, also wear protective clothing and limit sun exposure during use and for a week after stopping.

AHA preparations can be alternated with retinoid creams or vitamin C products. Avoid building a routine around repeated exfoliation: too much can strip away structures that retain water and healthy fats. A consistent routine is more useful than a crowded shelf auditioning for a chemistry department.13

How long do results take?

For acne treatments, expect fewer breakouts after 4 to 8 weeks and clearing around 16 weeks if the treatment works for you. Those are general acne treatment timelines, not a promise for every salicylic acid product. AHA peels gently improve texture over a few months; regular home AHA use can improve colour and texture, but there is no single timetable for every formula.34

Who should be careful?

Stop an AHA product if it causes burning, a rash, swelling or blisters. Seek medical care for severe reactions. If you are pregnant or trying to become pregnant, check with a dermatologist before treating acne yourself. See a dermatologist for deep, painful pimples, acne that scars, or acne that has not cleared after a few months of consistent treatment.45