In short
- Chemical exfoliants loosen the bonds between dead skin cells so they shed more evenly, leaving skin smoother and brighter.
- AHAs (glycolic, lactic, mandelic) work on the surface and suit dry, dull and sun-damaged skin. BHA (salicylic acid) is oil-soluble, gets into pores and suits oily, acne-prone skin. PHAs are the gentlest.
- Two or three times a week is enough for most people. Over-exfoliation is one of the most common causes of a damaged skin barrier.
- AHAs can increase sun sensitivity, so daily sunscreen is essential.
Exfoliation is the skincare step that can transform dull, rough skin in a few weeks, and the one most likely to go wrong. The difference lies in choosing the right acid for your skin and using less of it than you think.
What chemical exfoliants do
Your skin naturally sheds dead cells from its surface, but the process slows with age, sun damage and in oily or acne-prone skin, where cells can stick together and clog pores. Chemical exfoliants dissolve the “glue” between dead cells so they shed more evenly. The results:
- Smoother texture and a brighter, more even complexion.
- Fewer clogged pores and blackheads (especially with BHA).
- Better absorption of the products that follow.
- Gradual fading of dark spots and, with long-term use, softer fine lines.
AHAs: alpha hydroxy acids
AHAs are water-soluble and work mainly on the skin’s surface.
| AHA | Molecule size | Best for |
|---|---|---|
| Glycolic acid | Smallest; penetrates most | Normal to oily skin, sun damage, texture; the most potent and most irritating |
| Lactic acid | Larger | Dry and sensitive skin; also hydrating |
| Mandelic acid | Largest | Sensitive skin, deeper skin tones, acne-prone skin; gentle |
Typical leave-on strengths are 5% to 10% for daily or near-daily products. Strength also depends on pH: a lower pH means a stronger effect.
BHA: salicylic acid
Salicylic acid is oil-soluble, so it can travel into pores and clear out the mix of oil and dead cells that forms blackheads and breakouts. It’s also mildly anti-inflammatory.
- Strength: 0.5% to 2% in most over-the-counter products.
- Best for: oily, acne-prone and combination skin, blackheads and visible pores.
- Formats: leave-on liquids and gels, cleansers (shorter contact, gentler), spot treatments.
Our acne-prone skin routine shows where BHA fits.
PHAs: polyhydroxy acids
PHAs such as gluconolactone and lactobionic acid are larger molecules that penetrate slowly. They exfoliate gently, also act as humectants, and are often tolerated by sensitive skin that can’t handle AHAs.
Which acid should you choose?
| Your skin | Start with |
|---|---|
| Oily, blackheads, breakouts | Salicylic acid (BHA) |
| Dry, dull, rough | Lactic acid (AHA) |
| Sun damage, uneven texture, normal to oily | Glycolic acid (AHA) |
| Sensitive or reactive | PHA or mandelic acid |
| Deeper skin tone prone to dark marks | Mandelic or lactic acid, introduced slowly |
| Combination | BHA on the T-zone, lactic or PHA on the cheeks |
Not sure of your type? Start with how to find your skin type.
How often to exfoliate
- Start with two nights a week, on non-consecutive nights.
- Increase to three if your skin stays comfortable.
- Some people with oily, resilient skin can use a gentle BHA daily, but most skin does not need daily exfoliation.
- Never combine acids with scrubs, peels, cleansing brushes and retinoids in the same session.
How to use an exfoliating acid
- Cleanse and dry your skin completely.
- Apply the acid (toner, serum or pad), avoiding the eye area and the corners of the nose and mouth.
- Wait a minute, then apply a hydrating serum and moisturizer.
- The next morning: sunscreen.
Signs you’re over-exfoliating
- Stinging when applying a gentle moisturizer.
- Tightness, flaking or a tight, overly shiny look.
- Redness, warmth or rough patches.
- New breakouts in unusual places.
If you notice them, stop all exfoliants and follow our skin barrier repair plan for two to four weeks.
How long until you see results?
- 1 to 2 weeks: smoother texture, more glow.
- 4 to 6 weeks: fewer blackheads (BHA), more even tone.
- 8 to 12 weeks: softer dark spots and marks.
Purging can happen with exfoliants too, since they speed up turnover. Learn to tell it apart from irritation in purging vs. breakouts.
Sample weekly exfoliation schedules
| Skin | Mon | Tue | Wed | Thu | Fri | Sat | Sun |
|---|---|---|---|---|---|---|---|
| Oily, acne-prone | BHA | Rest | BHA | Rest | BHA | Rest | Rest |
| Dry, dull | Lactic | Rest | Rest | Lactic | Rest | Rest | Rest |
| With a retinoid | Acid | Retinoid | Rest | Acid | Retinoid | Rest | Retinoid |
| Sensitive | PHA | Rest | Rest | Rest | PHA | Rest | Rest |
“Rest” nights mean cleanser and moisturizer only. These schedules are starting points: adjust based on how your skin feels.
Physical vs. chemical exfoliation
Scrubs and brushes remove dead cells mechanically. Gentle ones (fine particles, soft cloths) can be fine for some people, but harsh scrubs with irregular particles can cause micro-tears and irritation. For most skin types, especially acne-prone and sensitive skin, a well-chosen chemical exfoliant is gentler and more even.
The bottom line
The best exfoliant is the gentlest one that gets results. Match the acid to your skin, start twice a week, moisturize after, and wear sunscreen every morning.
Frequently asked questions
Can I use AHA and BHA together?
Yes, many products combine them, and tolerant oily or combination skin can benefit. If your skin is sensitive, alternate them on different nights, or use BHA on the T-zone and AHA on the cheeks.
Can I use an exfoliating acid with retinol?
Not on the same night at first. Alternate nights (for example acid on Monday and Thursday, retinoid on other nights) once your skin is used to each one separately. Stop if you notice stinging, flaking or redness.
How do I know if I'm over-exfoliating?
Stinging when you apply gentle products, tightness, a shiny 'plastic' look, redness, flaking and new breakouts are typical signs. Stop all exfoliants and focus on barrier repair for two to four weeks.
This article is for general information only and is not medical advice. Skin is individual: for a skin condition, a reaction or anything that worries you, please see a dermatologist or doctor.
