What is chemical exfoliation?

How does chemical exfoliation work?

Your skin naturally sheds old surface cells and replaces them with newer ones. Age and sun exposure slow that process. Alpha hydroxy acids, usually shortened to AHAs, loosen the substances holding surface cells together so dead cells can shed more easily. Beta hydroxy acids, or BHAs, also remove dead cells, but dissolve in oil and reach into pores to help remove sebum, the oil your skin produces.23

Is chemical exfoliation better than physical exfoliation?

Neither method is best for every skin type. Physical exfoliation removes cells with a scrub, brush, sponge or pad; chemical exfoliation loosens them with a formula, so the bathroom does not need to become a sanding workshop. A mild chemical exfoliant can be preferable for dry, sensitive or acne prone skin because scrubbing can be too irritating. Oily, thicker skin can tolerate stronger methods, but skin type is not permission to ignore irritation.5

What are the benefits of chemical exfoliation?

Chemical exfoliation can improve rough texture, dullness and uneven colour. Smoother texture and more even tone are useful goals, rather than treating "renewal" as a complete product specification. Salicylic acid helps unclog pores, making it useful for blackheads and whiteheads. Glycolic acid can improve the appearance of fine lines and dark spots from mild sun damage or acne, and stimulate collagen, the protein that gives skin structure and support. These benefits depend on the acid and formula, not simply whether a product calls itself an exfoliant.236

Which acid and strength should you choose?

Lactic acid is one of the gentler AHAs and also helps moisturize skin. Salicylic acid is a useful choice when clogged pores are the main concern. Glycolic acid penetrates more deeply than other AHAs because its molecules are small, but it can be more irritating. Be cautious with glycolic acid if you have dry or sensitive skin, rosacea, eczema, an active skin infection or skin that is not healing.26

The percentage is only part of a product's strength. Exfoliation also depends on the acid, the formula's pH, meaning how acidic it is, and the other ingredients. For consumer glycolic and lactic acid products, safety criteria include a concentration of 10% or less, a final pH of at least 3.5 and protection or directions addressing increased sun sensitivity. Those are safety conditions, not a reason to start at 10%. An AHA appearing on an ingredient list can also serve another purpose, such as adjusting pH, rather than making the product an exfoliating treatment.4

How do you start using a chemical exfoliant?

1. 1Review your current routine. Prescription retinoids, retinol and benzoyl peroxide can already cause sensitivity or peeling; adding exfoliation can worsen dryness or breakouts.
2. 2Test a small area first. Do this before spreading a BHA product over a larger area; a small area test is also advised when starting glycolic acid.
3. 3Follow the product's application directions. Do not exceed the stated number of applications, and distinguish between a product meant to be rinsed off and one meant to stay on.
4. 4Start glycolic acid once or twice a week at night. Increase frequency only if your skin tolerates it; other exfoliants need their own label directions.
5. 5Apply moisturizer after exfoliating. Exfoliation can be drying.
6. 6Use sunscreen during the day. With glycolic acid, choose broad spectrum SPF 30 or higher and reapply every two hours.

There is no single schedule for all chemical exfoliation. Frequency depends on skin type and the method; more aggressive exfoliation generally needs less frequent use. Nighttime application is suitable for AHA products intended to stay on, but applying an acid at night does not remove the need for daytime sun protection.35

What should you avoid combining at first?

When starting glycolic acid, avoid combining it with other exfoliating acids, retinol or vitamin C serums. Reducing the number of active ingredients helps limit irritation and makes a reaction easier to trace. AHA products can be alternated with retinoid creams or vitamin C, rather than used together, but a prescription routine needs particular care because exfoliation can add to existing sensitivity.36

How long does chemical exfoliation take to work?

With home glycolic acid products, brighter skin or more even pigmentation can take several months of consistent use. Professional AHA peels also retexture skin over a few months, although office procedures can produce more dramatic changes. Professional glycolic peels use concentrations of 20% to 70% and involve controlled application and removal. Those treatment strengths are not a starting point for a home routine.36

Can you use chemical exfoliation on your face?

Yes. Facial exfoliants include AHA preparations for dry, normal and oily skin, and salicylic acid products sold as washes, toners, serums and moisturizers. The format alone does not determine how often to apply one. Follow its directions rather than assuming every toner stays on or every acid product belongs in a daily routine.23

Can you use chemical exfoliation on your body?

Yes. Lactic acid appears in body washes as well as facial products. It is used for keratosis pilaris, painless bumps caused by dead skin building up around hair follicles. These bumps commonly occur on the upper arms, legs and back, and sometimes the cheeks. Before using a BHA over a large body area, test a small area and follow the product's application limits.27

When should you stop or get medical advice?

• Never exfoliate sunburned skin or areas with open cuts or wounds.
• Avoid strong exfoliation if you have a darker skin tone or develop dark spots after acne, burns or insect bites. Aggressive exfoliation can increase pigmentation.
• Stop a BHA product and consult a physician if you develop irritation or prolonged stinging. Avoid BHA products on infants and children.
• AHA reactions can include rash, swelling, blistering and chemical burns; stronger skin peeling products carry greater risks.
• While using an AHA and for a week after stopping, use sunscreen, wear protective clothing and limit sun exposure.
• Low concentration glycolic acid is generally considered safe during pregnancy, but check with your healthcare provider before using it while pregnant or breastfeeding.