Alpha hydroxy acid refers to a group of natural acids added to skin care products and recommended by dermatologists as a treatment for various skin problems including sun damaged and aging skin. There are several kinds of alpha hydroxy acids. They include glycolic acid, citric acid, lactic acid, tartaric acid, malic acid and mandelic acid, which are derived from natural sources such as sugar cane, milk, grapes and citrus fruits. Glycolic acid, from sugar cane, and lactic acid, from sour milk, are the most common alpha hydroxy acids used in skin products because they penetrate skin the best.
In skin care products, alpha hydroxy acids are effective for treating signs of skin aging. The outermost layer of the epidermis called the stratum corneum is made up of skin cells called keratinocytes that are sloughed off regularly to reveal new cells underneath. With age, this process slows down, causing skin to look dull. Alpha hydroxy acids speed up this process by dissolving the glue-like substance between the cells so that they're shed more easily. This increased rate of sloughing, called desquamation, thins out the outer layer of the skin so that it reflects light better and looks more youthful.
Creams and ointments containing allantoin are used to treat skin conditions like diaper rash in babies, wind burned skin from exposure to cold, sunburned skin from overexposure to the sun, chapped lips and to ease the discomfort of cold sores. Allantoin can also be applied to scrapes, burns and cuts as a way to soothe and protect the area. It also appears to speed up wound healing by stimulating new skin cell growth and is sometimes used to treat radiation skin burns in people who are undergoing radiation treatment for cancer. Allantoin is available as a shampoo combined with coal tar to treat scalp psoriasis, seboorhea, dandruff and eczema involving the scalp.
Research shows that alpha hydroxy acids help to soften fine lines and wrinkles, even out skin pigmentation and improve skin texture. With regular use, skin feels smoother and looks more youthful. There's also evidence that alpha hydroxy acids boost production of collagen, a protein in the dermis that gives skin support and its ability to resist wrinkling and sagging. Alpha hydroxy acids are available in anti-aging skin care products at concentrations of 5% of 10% for home use.
Dermatologists and health care professionals use alpha hydroxy concentrations of 50% to 70% to do superficial chemical peels or "lunchtime peels." These peels provide faster improvements in skin appearance and texture, but they have the greatest benefits when they're done as a series a few weeks apart. These peels cause moderate amounts of skin redness, irritation and burning and give the face a flushed appearance that may last for several days.
It's not necessary to get a chemical peel to get results from alpha hydroxy acids. Lower concentrations of these acids available in skin care products for home use have skin rejuvenating benefits when they're used regularly over several months. The weak acids increase the turnover of dead skin cells, soften fine lines, lighten pigmented areas and give skin a smoother texture that reflects light better. Alpha hydroxy acids also function as humectants, drawing water from the environment to keep skin moist. Lactic acid is a particularly effective humectant and moisturizer.
Alpha hydroxy acids are also effective for treating acne, although another type of weak acid called beta hydroxy acids are a better choice for treating acne-prone skin. That's because beta hydroxy acids are lipid soluble. This means they're better able to penetrate clogged sebaceous glands and exfoliate the dead skin cells inside that cause clogged pores and acne bumps. Beta hydroxy acids are best for acne-prone skin, while alpha hydroxy acids are a better choice for rough, sun-damaged skin.
People who use alpha hydroxy acids for facial rejuvenation should always wear a sunblock for sun protection. Since alpha hydroxy acids thin the stratum corneum, they make skin more susceptible to sun damage. Fortunately, a sunscreen with a high SPF (30 or greater) that blocks UVA and UVB rays, a hat and sunglasses provides some degree of protection against ultraviolet light.
Alpha hydroxy acids appear to be safe, but they can cause skin irritation, especially during the first few weeks. The degree of irritation varies with the concentration of the acid and the vehicle it's suspended in. People with sensitive skin may have more pronounced skin irritation when using alpha hydroxyl acids and will benefit by using a lower concentration or apply the product every other day to reduce irritation.
In summary, alpha hydroxy acids are available in a number of skin care products these because they work well for improving skin texture, fine wrinkles and increased pigmentation, but it's important to wear a sunscreen when using these products - and to be patient. It takes time to see results.