Can lactic acid cause purging?

What happens when you use lactic acid?

Lactic acid is an alpha hydroxy acid, or AHA. These acids loosen the bonds between surface skin cells so dead cells can shed. Lactic acid also acts as a moisturizer and is one of the gentler AHAs, making it an option for sensitive skin and rough texture. That does not make a worsening breakout a necessary step toward smoother skin. There is no reliable lactic acid purging duration to use as a countdown for continuing an irritating routine.2

Which symptoms mean you should stop?

Burning, stinging, itching, peeling and skin discoloration can be signs of sensitivity. Discoloration can look like redness or a shade darker than your usual skin tone. Irritation can also produce bumps, so bumps alone do not tell you what is happening. If a new product causes a reaction, gently wash it off and stop using it. A cool compress or petroleum jelly can help relieve the reaction.34

See a dermatologist if the reaction is severe and does not improve with those measures. Get medical help if symptoms remain very bothersome or do not improve after about a week of home care. If the cause is unclear, a dermatologist can assess your routine and decide whether allergy patch testing would help.34

How can you introduce lactic acid more carefully?

Testing a small area first can help predict a negative reaction, even if it makes a less impressive routine reveal.4

1. 1Test before applying widely. Use your normal amount on a small area, such as the underside of your arm or elbow bend. General product testing guidance uses twice daily application for seven to 10 days; follow the product's directions for how long to leave it on.
2. 2Check your existing routine. Prescription retinoids, retinol and benzoyl peroxide can increase sensitivity or peeling. Adding exfoliation can worsen dryness or breakouts. Avoid introducing lactic acid alongside a new glycolic acid product.
3. 3Keep exfoliation gentle. Frequency depends on your skin and the product; more aggressive exfoliation needs less frequent use. Do not exfoliate sunburned skin, open cuts or wounds.
4. 4Follow exfoliation with moisturizer. Use SPF 30 or higher sunscreen every day, because facial acids increase vulnerability to sun damage.

Keeping the routine simple makes it easier to identify a troublesome product, which is one useful reason not to turn the bathroom shelf into a casting call. Be particularly cautious with strong exfoliation if you develop dark spots after irritation or have a darker skin tone.15

Why does glycolic acid sting my face?

Glycolic acid has smaller molecules than other AHAs and penetrates more easily, making it potentially more irritating. Sensitive, dry or unhealed skin needs particular caution. Start glycolic acid once or twice weekly at night rather than borrowing that schedule as a universal rule for every acid.25

Does a tingling exfoliant mean it is working?

Tingling is not a useful measure of exfoliation. It is also a symptom of sensitive skin, including reactions you can feel without visible changes. Judge tolerance by whether your skin remains comfortable, not by how noticeable the product feels.3