Some natural acids are present in our body that help us survive, whereas, some are synthetic that are used in a variety of products. One such group of acids, that is useful to us, is alpha hydroxy acids. These acids consist a variety of important acids, such as, glycolic acid, lactic acid and citric acid. Alpha hydroxy acids are carboxylic acids (acids with -COOH group) with a hydroxyl (-OH group) on the adjacent carbon or the alpha carbon, of the carboxyl group. These can be naturally occurring or synthetic. These acids have found a wide range of application in the cosmetic industry, as they have proven to be safe on the skin. Due to their acidic nature they act as good reducing agents and therefore, play a role in scavenging free radicals. This property has helped them to make a mark in the anti aging creams section to delay the occurrence of wrinkles. The major acids that are being used currently in the cosmetic industry are glycolic acid, lactic acid, malic acid, and citric acid. Glycolic Acid This acid has the smallest structure in the category of AHA. It is a crystalline solid, soluble in water. It is widely used in various skin care products. The most popular application of this acid is in chemical peels at a concentration of 20 to 70%, when prescribed by dermatologists, or as low as 10% in home products. Glycolic acid is used for acne, wrinkles, hyper-pigmentation, and hyperkeratosis. When used in keratosis, glycolic acid weakens the binding of lipids to the dead skin cells and thus, exfoliates the skin. Lactic Acid The main source of this acid is sour milk. Lactic acid is also used as an exfoliating agent, however, it is very gentle, hence, preferred for sensitive skin. More importantly, lactic acid acts as a very effective antibacterial agent. It maintains the pH of the skin and thus, prevents bacterial infections, which makes it a vital component of various antibacterial products. It is used in making lotions for smoothening elbows and heels. Lactic acid has the property of enhancing the absorption of cosmetics such as sunscreen lotions. Citric Acid Citric acid is present in fruits, such as, lemons, oranges, and grapefruits. Citric acid is a very effective antioxidant and therefore, present in many anti-aging or face-lift creams. It is also a good astringent and helps in the treatment of nasty spots. It also improves the effectiveness of skin moisturizers. Citric acid is also used in hair care products. It is also used in the post perm treatment. These were the major AHAs used in the cosmetic industry. The rest, such as malic and tartaric acid are less used in this industry, as there are certain safety issues associated with their use on the skin. These carboxylic acids are popularly used in anti-aging creams and are safe to use. However, ensure that you take a look at the chemical composition of the cosmetics before using them.