Azelaic acid

Azelaic acid is a saturated dicarboxylic acid found naturally in wheat, rye, and barley. It is a natural substance that is produced by Malassezia furfur (also known as Pityrosporum ovale), a yeast that lives on normal skin. It is effective against a number of skin conditions, such as mild to moderate acne, when applied topically in a cream formulation of 20%. Azelaic acid may be useful as a hair growth stimulant.

Properties
Azelaic acid is:
 * Antibacterial: it reduces the growth of bacteria in the follicle (Propionibacterium acnes and Staphylococcus epidermidis).
 * Keratolytic & comedolytic: it returns to normal, the disordered growth of the skin cells, lining the follicle.
 * Scavenger of free radicals and reduces inflammation.
 * Reduces pigmentation: it is particularly useful for darker-skinned patients, who have melasma, or whose acne spots leave persistent brown marks known as actinic lentigenes (per the product insert: "There have been reports of hypopigmentation after use of azelaic acid.  Since azelaic acid has not been well studied in patients with dark complexions, these patients should be monitored for early signs of hypopigmentation.").
 * Non-toxic, and is well tolerated by most patients.

Azelaic acid does not result in:
 * Bacterial resistance to antibiotics.
 * Reduction in sebum production.
 * Photosensitivity (easy sunburn).
 * Staining of skin or clothing.
 * Bleaching of normal skin or clothing.

Because 20% azelaic acid can be a skin irritant, it should be used only when prescribed by a physician.

Acne treatment
Azelaic acid is used to treat mild to moderate acne, i.e. both comedonal acne and inflammatory acne. It works in part by stopping the growth of skin bacteria that cause acne, and by keeping skin pores clear.

Hair loss
Azelaic acid may be useful as a hair growth stimulant. A research report by Stamatiadis in 1988 suggested that azelaic acid (and combinations of it, with zinc ion and vitamin B6) was a strong type I 5-alpha reductase (5-AR) inhibitor. The enzyme, 5-AR (both Types I and II) convert testosterone to dihydrotestosterone (DHT). DHT has been shown to contribute to prostate enlargement (benign prostatic hyperplasia, BPH) and to damage hair follicles. However, no clinical studies have confirmed its efficancy in helping with hair loss.