The most common allergic reaction to hair care products is allergic contact dermatitis. This reaction is a red, itchy and scaly rash at skin sites that touched the allergen. The skin can even develop small blisters when the reaction is really bad. This rash, also called type 4 delayed hypersensitivity reaction, is different than hives (or welts), which many people associate with allergic reactions. Think of poison oak or poison ivy, which produce the classic and severe form of allergic contact dermatitis in many people. Allergic contact dermatitis is at first a slow type of allergy that builds into a rash. It can take days or weeks, and often happens after a person has successfully tolerated an ingredient or product in the past. Hair care products are full of allergens that can cause allergic contact dermatitis. The most notorious allergens in hair care products for allergic reactions include the fragrances and preservatives. Even ‘natural’ fragrances can cause trouble, citrus being one of those. Trouble develops because these taunting allergens remain on the skin due to:
- Sprays, which send airborne droplets onto facial skin, including the delicate eyelid skin. Eyelid skin is often the 'canary in the coal mine' that reacts to allergens first.
- Product that rinses over the skin such as the facial skin, behind the ears, and down the neck. This would include shampoos and conditioners (again eyelid skin reacts promptly because it is thin). It is common for us to forget to fully wash product residue off our skin. In this instance the rash often shows up behind the ears and in the nape of the neck, as well as the eyelids.
- Product on the hair shafts themselves, such as mousse, gels and even hair dyes absorbed into the hairs can cause allergic contact dermatitis as the hair touches skin over the course of the day.