A chemical peel is a body treatment technique used to improve and smooth the texture of the skin, often facial skin, using a chemical solution that causes the dead skin to slough off and eventually peel off. The regenerated skin is usually smoother and less wrinkled than the old skin. Some types of chemical peels can be purchased and administered without a medical license, however people are advised to seek professional help from a dermatologist, esthetician, plastic surgeon, oral and maxillofacial surgeon, or otolaryngologist on a specific type of chemical peel before a procedure is performed.
There are several types of chemical peels.
Alpha hydroxy acid peels
Alpha hydroxy acids (AHAs) are naturally occurring carboxylic acids such as glycolic acid, a natural constituent of sugar cane juice and lactic acid, found in sour milk and tomato juice. This is the mildest of the peel formulas and produces light peels for treatment of fine wrinkles, areas of dryness, uneven pigmentation and acne. Alpha hydroxy acids can also be mixed with a facial wash or cream in lesser concentrations as part of a daily skin-care regimen to improve the skin's texture.
AHA peels may cause stinging, skin redness, mild skin irritation, and dryness.
Beta hydroxy acid peels
It is becoming common for beta hydroxy acid (BHA) peels to be used instead of the stronger alpha hydroxy acid (AHA) peels due to BHA's ability to get deeper into the pore than AHA. Studies show that BHA peels control sebum excretion, acne as well as remove dead skin cells to a certain extent better than AHAs due to AHAs only working on the surface of the skin. Salicylic acid is a beta hydroxy acid.
Jessner's peel solution, formerly known as the Coombe's formula, was pioneered by Dr. Max Jessner, a German-American dermatologist. Dr Jessner combined 14% salicylic acid, lactic acid, and resorcinol in an ethanol base. It is thought to break intracellular bridges between keratinocytes. It is very difficult to "overpeel" the skin due to the mild percentages associated with the acid combination, and does not penetrate as deeply as other chemical peels.
Retinoic acid peel
Retinoic acid is a retinoid. This type of facial peel is also performed in the office of a plastic surgeon, oral and maxillofacial surgeon, or a dermatologist in a medical spa setting. This is a deeper peel than the beta hydroxy acid peel and is used to remove scars as well as wrinkles and pigmentation problems. It is usually performed in conjunction with a Jessner; which is performed right before, in order to open up the skin, so the retinoic acid can penetrate on a deeper level. The client leaves with the chemical peel solution on their face. The peeling process takes place on the third day. More dramatic changes to the skin require multiple peels over time.
Croton oil / Phenol peel
Formerly known as a phenol peel, this skin treatment was re-popularized by Dr. Gregory Hetter. In a series of articles, he covers its historical use on a clandestine basis by early Hollywood stars in the 1920s to maintain their youthful appearance, to its early incorporation into rejuvenating medical practice in the 1960s by Dr. Thomas Baker, all the way to developing a modern basis for its use and dosage. Briefly, the active ingredient is clearly the croton oil component, which previously was poorly understood or deliberately obfuscated. It is the basis for a deep chemical peel, which causes an intense caustic exfoliating reaction in the skin, and eventually results in regeneration of the dermal architecture, effectively restoring younger dermis in a way that cannot be replicated by other, more superficial peels.    
Complications of chemical peels
The deeper the peel, the more complications that can arise. Professional strength chemical peels are typically administered by certified dermatologists or licensed estheticians. Professional peels and lower-concentration DIY home peel kits can pose health risks, including injury and scarring of the skin. Possible complications include photosensitivity, prolonged erythema, pigmentary changes, milia (white heads), skin atrophy, and textural changes.
Light chemical peels like AHA and glycolic acid peels are usually done in medical offices. There is minimal discomfort so usually no anesthetic is given because the patient feels only a slight stinging when the solution is applied. No pain killer is needed.
Medium peels like TCA are also performed in the doctor’s office or in an ambulatory surgery center as an outpatient procedure and can cause more discomfort. Frequently, the combination of a tranquilizer like diazepam and an oral analgesic is administered. TCA peels often do not require anesthesia even if the solution itself has - at the contrary of phenol - no numbing effect on the skin.[clarification needed] ;patient usually feels a warm or burning sensation.
Phenol was historically a deep chemical peel. Early phenol peel solutions were very painful and most practitioners would perform it under either general anesthesia, administered by an MD-anesthesiologist or nurse anesthetist. Today it is more correctly referred to as a Croton oil peel, since that has proven to be the active ingredient responsible for most of its effects. Recent formulations allow more variation in the depth of treatment, and allow its use under sedation either orally or intravenously, usually in conjunction with local anesthetic injections.
- Chemical Peels | The Ageing Skin
- Textbook of Chemical Peelings, P.Deprez, Chapt 8, Informa Healthcare
- Textbook of Cosmetic Dermatology, R.Baran, Chapt 54, Informa Healthcare
- "What Happens During a Jessner’s Peel?". Skin NV. Retrieved 25 July 2014.
- Plast Reconstr Surg. 2000 Jan;105(1):227-39; discussion 249-51. An examination of the phenol-croton oil peel: Part I. Dissecting the formula. Hetter GP.
- Plast Reconstr Surg. 2000 Jan;105(1):240-8; discussion 249-51. An examination of the phenol-croton oil peel: Part II. The lay peelers and their croton oil formulas. Hetter GP.
- Plast Reconstr Surg. 2000 Feb;105(2):752-63. An examination of the phenol-croton oil peel: Part III. The plastic surgeons' role. Hetter GP.
- Plast Reconstr Surg. 2000 Mar;105(3):1061-83; discussion 1084-7. An examination of the phenol-croton oil peel: part IV. Face peel results with different concentrations of phenol and croton oil. Hetter GP.
- Halaas YP: Medium depth peels. Facial Plas Surg Clin North Am 2004 Aug; 12(3):297-303