People of African descent face unique hair concerns, and hair straighteners, relaxers and extensions can break, burn and otherwise damage the hair and scalp.
According to Marta I. Rendon, M.D., associate clinical professor at both the University of Miami and Florida Atlantic University, Boca Raton, African descent applies to several groups of patients, including, but not exclusive to, African Americans, African Caribbeans, Hispanics with African heritage and African immigrants.
"Each type of hair has specific physical and mechanical properties that give it certain qualities of shape, curl, density and (vulnerability) to breakage," she says.
She adds that people of African descent have fewer follicular units per mm2 in their scalp than either Asians or Caucasians; therefore, the hair is less dense. It also has less tensile strength, meaning that it breaks more easily and is more difficult to comb.
All of these properties make the hair vulnerable, ironically, to several common practices and products that are intended to make it more manageable.
"Several of the straightening products and practices can make things worse, because they break, burn and irritate the hair, and can cause allergic dermatitis of the scalp," Dr. Rendon says.
Historically, straightening products have contained formaldehyde, which is a carcinogen and can also cause life-threatening allergic reactions.
Therefore, some of the newer straightening products and procedures, often called "Brazilian treatments" and marketed as keratin compounds, are advertised as being "formaldehyde-free." Japanese straightening products are also available.
The challenge is to identify which ingredient in the formaldehyde-free products straightens the hair, Dr. Rendon says.
So-called "relaxing" agents are also often used by patients of African heritage or others with very curly hair. In these products, which loosen the curl and make the hair easier to blow dry and comb, the active ingredient is typically lye, which can also cause allergic contact dermatitis, dry scalp, and scalp infections.
Patients who use straighteners, relaxers, blow dryers and flat irons can eventually lose their hair, Dr. Rendon says. "The hair just can't tolerate all these procedures."
Other procedures that can cause traction alopecia are the gluing of hair extensions to the scalp and the fusing of hair strands to give the illusion of more volume. Some hair extensions are now fastened with clips, which create less traction than glue.
Newer flat irons are intended to cause less damage to the hair. The manufacturers emphasize that the irons are made of ceramic and, more recently, tourmaline, and claim that they are, therefore, less damaging to the hair.
As with many cosmetic products and devices, though, the devil is in the detail of less regulatory accountability, Dr. Rendon says.
"Many cosmetic products and devices are put on the market with very little research," she says. "Some companies, for example, may have tested the products in as few as 20 patients."