Research has shown that this combination in "no lye" relaxers results in less scalp irritation than lye relaxers, but the same safety rules apply for both. They should be used properly, left on no longer than the prescribed time, carefully washed out with neutralizing shampoo, and followed up with regular conditioning.

For those who opt to straighten their own hair, it's wise to enlist help simply because not being able to see and reach the top and back of the head makes proper application of the chemical and thorough rinsing more of a challenge.

Some stylists recommend applying a layer of petroleum jelly on the scalp before applying a relaxer because it creates a protective barrier between the chemical and the skin. Scratching, brushing, and combing can make the scalp more susceptible to chemical damage and should be avoided right before using a relaxer.

Parents should be especially cautious when applying chemicals to children's hair and should keep relaxers out of children's reach. There have been reports of small children ingesting straightening chemicals and suffering injuries that include burns to the face, tongue, and esophagus.

How often to relax hair is a personal decision. According to Pearl Freier, an instructor at the International Academy of Hair Design in South Daytona, Fla., relaxing at intervals of six to eight weeks is common, and the frequency depends on the rate of a person's hair growth.

Leslie F. Safer, M.D., a dermatologist in Albany, Ga., who has treated women with scalp irritation from relaxers, says straightening every six weeks is too frequent, in his opinion. Relaxers can cause hair breakage in the long term, he says, and blow drying and curling can do more damage.

Consumers should be aware that applying more than one type of chemical treatment, such as coloring hair one week and then relaxing it the next, can increase the risk of hair damage. "The only color we recommend for relaxed hair is semi-permanent because it has no ammonia and less peroxide," compared with permanent color, Freier says.

Hair Dye Reactions
As with hair relaxers, some consumers have reported hair loss, burning, redness, and irritation from hair dyes. Allergic reactions to dyes include itching, swelling of the face, and even difficulty breathing.