Shampoos effectively wash hair and give hair shine. Special formulations target specific hair types and problems, such as dandruff or color-treated hair. Unfortunately, some shampoos contain ingredients that actually dry out hair and irritate the skin. Cheaper shampoos typically contain ingredients that are harsher. Some salon brands and higher quality store brands may not contain these ingredients.
Sulfates
The majority of shampoos available at drugstores and supermarkets contain either sodium lauryl sulfate (SLS) or sodium laureth sulfate (SLES). These sulfates produce a large amount of foam, giving shampoos the rich lather that many people consider desirable. Unfortunately, this rich lather may actually be unhealthy for hair and skin. According to information from the American College of Toxicology by Healthy Communications, patch tests showed sulfates to be irritants at concentrations of 2 perfect or greater. Most shampoos contain a concentration of up to 20 percent. Rat studies have also shown SLS to cause hair follicle damage, which could theoretically result in hair loss.
Formaldehyde
Formaldehyde, a chemical used for embalming, is released by two preservatives contained in shampoos--DMDM hydantoin and imidazolidinyl. This is particularly true of infant shampoo. Formaldehyde has disinfectant qualities, and its low cost makes it an attractive option for shampoo companies. In 1983, the Division of Cancer Cause and National Cancer Institute suspected the chemical as a carcinogen and recommended further investigation, according to 1stHolistic.com. Formaldehyde exposure may also lead to DNA damage.
Coal Tar Dyes
Dandruff shampoos may contain coal tar dyes. According to Pure Zing, coal tar dyes have carcinogenic qualities. These chemicals may increase the risk of Hodgkin's disease, non-Hodgkin's lymphoma and multiple myeloma. Additionally, other adverse effects may result from use, such as severe allergic reactions, headaches, nausea and fatigue.
Triethanolamine
Triethanolamine (TEA) is a detergent found in shampoo. Eye irritation as well as dry hair and skin may occur with use. TEA is restricted in Europe because of possible carcinogenic effects. Possible increased risk of kidney or liver cancer may be associated with long-term absorption of TEA into the skin.
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