Wednesday, July 11, 2007
The Perils of Dye
A patient came into our after-hours clinic this week complaining of a swollen lip. Cause: an allergic reaction to mustache dye (which he'd used before). He applied it, left it on overnight as per instructions, and woke the following morning with a swelling and itching upper lip.
Many -- in fact, most -- allergies don't appear until the patient has been exposed to the allergen multiple times. Anaphylactic reactions to bee stings or penicillin, for instance, generally don't occur the first time the person is stung or dosed; the extreme sensitivity is brought on by repeated exposures. This patient's history illustrates that fact. This is the same way vaccines work, actually; this is why we give 'booster shots', to boost the amount of antibodies the body forms in reaction to the protein injected - it generally is a purified protein derived from the virus (as in hepatitis) or toxin (as in tetanus) you're trying to protect against.
Several years ago I had another patient who had a reaction to hair dye. Hers was much more serious and could in fact have been a chemical burn -- I'm still not sure. She developed a deep ulcer at the top of her scalp, which eventually healed but she permanently lost the hair on that part of her scalp and later required plastic surgery.
I'm not sure how often people develop reactions to hair dye, but these reactions can be difficult to predict. They fall into the contact dermatitis category (like cosmetics or nickel allergies). The only advice we really have, when a patient develops a reaction to dye or other topical substances, is avoidance. Oh, and Benadryl is helpful too.