Ammonium lactate is an organic compound used as an active ingredient in certain skin creams and lotions, usually available only by prescription, to treat various skin conditions. This compound works as a moisturizer and exfoliant. It is sometimes used to treat xerosis, the medical term for dry skin, and is also sometimes used as a scaly skin condition treatment, for example when treating icthyosis vulgaris, a genetic condition that causes scaly, dry and slightly thickened skin. Creams and lotions with ammonium lactate are sometimes also prescribed to help relieve the itching related to these and other skin conditions. Ammonium lactate can irritate skin, increases sensitivity to ultraviolet light, and is not advised for applying to the face unless one has been advised to do so by a medical professional.
In chemical terms, this compound consists of ammonium hydroxide, or ammonium salt, combined with lactic acid, or milk acid. Lactic acid is an alpha-hydroxy acid and has a peeling, or exfoliating, effect when applied to the skin. In ammonium lactate, the acidity of lactic acid is reduced by ammonium hydroxide, but the compound is still exfoliating, contributing to its effectiveness as a treatment of scaly, dry, and thickened skin. Ammonium lactate also has hygroscopic properties, meaning it helps the outermost layer of the skin, the so-called stratum corneum, absorb moisture when applied topically.
Usually, the instructions for using a topical cream or lotion containing ammonium lactate are to apply it to clean, dry skin twice per day. The product should be carefully and thoroughly rubbed into the affected area, and should not be applied to broken, excessively chapped, sunburned, or recently shaved skin. In some cases, the medicated solution can cause a stinging or burning sensation. It is advisable to wash one's hands both before and after application.
Ammonium lactate can cause minor skin irritation, such as redness and peeling, and can occasionally cause more serious side effects on treated skin such as discoloration, eczema, and small red spots due to broken capillaries. This ingredient can also make skin sensitive to sun or other sources of ultraviolet light like tanning booths. It is recommended that one use a sunscreen with at least SPF 15 and avoid direct sunlight by staying in the shade or covering skin with clothing while using ammonium lactate products. Pregnant and breastfeeding women should consult a doctor before using this prescription treatment.