What chemical peels actually do
A chemical peel applies an acid solution to the skin to cause controlled exfoliation. The depth of the peel — superficial, medium, or deep — determines which skin layers are affected, how dramatic the results are, and how much recovery is required.
The result you're after is new skin production: the controlled exfoliation removes the surface layer, the skin's healing response generates new collagen and cell turnover, and the result is improved texture, tone, and clarity. Different acids have different mechanisms and target different skin concerns.
Glycolic acid: the workhorse for texture and brightness
Glycolic acid (AHA — alpha-hydroxy acid) derived from sugar cane is the most-used peel acid. It works by loosening the bonds between dead skin cells, promoting shedding and revealing newer skin beneath.
Best for: Overall brightening, fine lines, mild hyperpigmentation, dull skin, sun damage, general texture improvement.
Skin types: Most skin types, though concentration and contact time should be adjusted for sensitive skin. For very dark skin types, glycolic at high concentrations carries PIH risk — start lower.
Downtime: Light glycolic (20–40%): 1–3 days of mild redness and possible flaking. Medium glycolic (50–70%): 3–5 days.
When to use it: When your concern is surface-level — dullness, minor texture, mild sun spots. For the maintenance patient who wants to keep skin in good condition. Series of 4–6 monthly peels produces meaningful cumulative improvement.
Salicylic acid: the acne-focused choice
Salicylic acid (BHA — beta-hydroxy acid) is oil-soluble, which means it penetrates into pores rather than working only at the skin surface. This makes it uniquely effective for oily, acne-prone skin.
Best for: Acne and oily skin, clogged pores, blackheads, mild post-acne marks (PIH), oily texture.
Skin types: Particularly good for oily to combination skin. Not the first choice for dry or sensitive skin. Generally safer for darker skin types than glycolic at equivalent depth.
Downtime: Minimal — typically 1–2 days of mild redness, possible light flaking. Often called a "lunchtime peel."
When to use it: When your primary concern is acne, clogged pores, or oiliness. Works well alongside topical acne treatments and can be repeated monthly.
Lactic acid: the gentlest option for sensitive or dry skin
Lactic acid (AHA, milk-derived) is the gentlest of the common peel acids. Larger molecular size means shallower penetration; it works primarily on the very surface and has a mild hydrating effect alongside its exfoliation.
Best for: Sensitive or dry skin, dehydration, mild dullness, first-time peel patients who want to test tolerance.
Skin types: Particularly suited for dry, sensitive, or reactive skin. Safe for most darker skin types at appropriate concentrations.
Downtime: Minimal — usually 1 day or less of mild redness.
When to use it: When you want exfoliation without the potential irritation of glycolic or salicylic. For patients who've had bad reactions to other peels. As a first introduction to chemical peels.
TCA: the high-impact option with real downtime
Trichloroacetic acid (TCA) penetrates deeper than AHAs or BHAs, reaching the mid-dermis at higher concentrations. It produces a "frosting" reaction (visible whitening of the skin) as it denatures proteins in the treated layer. The results can be dramatic — but so can the recovery.
Best for: Significant hyperpigmentation, melasma, sun damage, moderate wrinkles, deeper texture concerns, post-acne scarring (moderate depth).
Skin types: More risk for darker skin types — PIH from TCA can be significant and persistent. Protocols for Fitzpatrick IV–VI require specific pre-treatment, lower concentrations, and careful monitoring. Not contraindicated, but requires expertise and caution.
Downtime: 5–7 days of visible peeling. Day 3–4 is typically the most obvious. Plan around your social calendar; this is not a lunchtime treatment.
When to use it: When light peels haven't produced adequate results. For significant hyperpigmentation or sun damage where you need deeper effect. When you can commit to 5–7 days of real recovery and strict post-peel sun avoidance.
Any provider offering TCA without a skin assessment, without discussing PIH risk for your skin type, and without a detailed post-peel protocol is cutting corners. TCA on dark skin without proper protocol can cause hyperpigmentation that takes months to resolve.