Done correctly, exfoliation helps your skin purge dead cells, revealing a better complexion underneath. That magic draws us to the practice but also makes us overzealous. At home, aggressive exfoliation can cause skin damage, irritation and breakouts.

So what kinds of products do the job best? We turned to dermatologists and an aesthetician for answers.

Do not exfoliate severely inflamed skin.

Dr. Arash Akhavan, founder of the Dermatology & Laser Group in New York, tells patients who have inflamed cases of acne or rosacea to skip exfoliation. "Exfoliation inherently causes some level of trauma to the skin, leading to a small amount of inflammation," Akhavan said. That irritation would overwhelm skin that is already inflamed.

Chemical peels are best, usually.

There are two main types of exfoliation: chemical and mechanical. Chemical exfoliations use fruit enzymes or acids like glycolic acid, derived from sugar, and lactic acid, which is made from milk. Mechanical exfoliations use beads, brushes and razors (dermaplaning) to lift dead cells off the skin.

"A scrub or tool like a brush involves your own manual pressure, and people tend to be very aggressive with them," said Dr. Sejal Shah, founder of SmarterSkin Dermatology in New York. "Scrubs made from fruit pits and nut shells create small tears in the skin."

With cosmetic procedures, "the injury is controlled and typically microscopic," Shah said. Not so with tears caused by harsh exfoliation. "I think most dermatologists tend to like chemical exfoliants because they are overall more effective while being gentler on the skin," she said. Chemical exfoliants gently break the bonds that hold dead skin cells together, so they can be easily rinsed away.

But for skin with a history of irritation or allergy from cleansers and lotions, mechanical is the way to go. With a brush, there are no ingredients for the skin to react to.

Most Clarisonic-style brush users press too hard. The bristles should lightly graze the skin to get the benefit of their back-and-forth, pore-cleaning motion, said Jeannel Astarita, an aesthetician and owner of Just Ageless in New York.

If you are new to exfoliation, start with enzymes.

Astarita prefers fruit enzymes like the papaya in DefenAge 2-Minute Reveal Masque ($74) because they are gentler and better tolerated than acids. For scrub loyalists, a product like Juara Radiance Enzyme Scrub ($38) combines apple enzymes and a fine, smooth polish. Know that the enzymes do most of the exfoliating work — no rubbing allowed.

For a stronger peel, graduate to acids.

Alpha hydroxy acids (AHA) — typically glycolic, lactic and citric — are stronger exfoliants than enzymes. Try them after a few weeks of enzyme exfoliation with no irritation. "Lactic acid is great for oily, sensitive skin and has good outcomes treating oiliness in African-American skin," said Dr. Macrene Alexiades, a New York dermatologist.

"Citric acid is a relatively weak alpha hydroxy acid," Alexiades said. "It does not peel the skin unless used at higher concentrations or long exposure times."

Glycolic acid, though, is the star AHA. It is the smallest molecule of the acids, so it penetrates deepest to treat fine lines, dullness and superficial hyper-pigmentation, and it is a humectant. Think of it as a skin care generalist, an assist for achieving the most beloved of skin goals: glow. AHAs that are stand-alone exfoliators are most effective. Exfoliating cleansers, for example, are not on the skin long enough to work.

But how strong is your peel?

Keep in mind that peel products are only as effective as their ingredient concentration and pH allow them to be. A measure called free acid value indicates the real amount of acid your skin will be able to use but is hardly ever disclosed. There are some exceptions.

The Glytone Rejuvenating Mini Peel Gel ($64) is a straightforward glycolic exfoliator that lists its free acid value of 10.8 right on the bottle. That is in the moderate strength range, so you will see better texture and more even tone over time (but could also see slight irritation).

The Drunk Elephant TLC Sukari Babyfacial ($80) combines all the AHAs at a peel-friendly acidic 3.5 pH. It also features salicylic acid, a beta hydroxy acid. "BHAs are oil soluble, which allows them to work deeper, inside the pores," Shah said. "It's a good treatment for acne-prone skin."

When paired with AHAs in relatively small amounts, as in this product, salicylic acid makes delivery of all the active ingredients more efficient.

For most products, unfortunately, you will have to judge strength by feel. "If you put it on and it itches, it's relatively mild," Alexiades said. "If it stings or burns, it's stronger."