A rare sensitivity to certain chemicals, particularly a substance called p-phenylenediamine (PPD), can cause an individual to have an allergic reaction to hair dye. Often, the allergic reaction is fairly mild, producing signs like burning, itching, and redness. In very rare instances, a hair dye allergy can bring on a life-threatening condition known as anaphylaxis, which can be recognized by symptoms like swelling of the throat and face, hives, rapid heartbeat, disorientation, and discoloration of the skin. Those who wish to color their hair may be able to avoid an allergy to hair dye by always testing a product on a small area of the skin.
Many medical experts believe that a sensitivity to the compound PPD, contained in many cosmetic dyes, is responsible for causing a small number of individuals to have an allergic reaction to hair dye. For many of these individuals, this reaction produces unpleasant but mild signs, such as itching, burning, and redness on and around the scalp. In many cases, the symptoms of a mild allergic reaction will diminish within hours or days. Taking an over-the-counter antihistamine may provide relief from symptoms until the reaction comes to an end.
In very rare cases, an allergic reaction to hair dye can cause an extremely serious condition called anaphylaxis. This condition occurs when the immune system detects the presence of an allergen and responds by releasing a large amount of a substance called histamine. Anaphylaxis can produce a number of signs, such as confusion, puffy face and eyes, closure of the throat, racing heart, hives, and skin discoloration. If left untreated, anaphylaxis can quickly lead to death. Therefore, those who show signs of this condition should seek medical attention as soon as possible.
It may be possible to prevent an allergic reaction to hair dye by performing a procedure commonly known as a patch test prior to applying dye to one’s hair. When doing a patch test, a small amount of dye is applied to a patch of skin in an inconspicuous area, such as the inner arm. The dye is allowed to sit on the skin for one to two days. If no symptoms occur at the treated area, the dye can most likely be applied to the hair without causing a reaction. As a product’s formulation can change, health experts stress that a patch test should be performed each time an individual plans to use hair dye.