Contact dermatitis is the major condition associated with cosmetic allergies. It is characterized by the appearance of redness, itching and swelling after a substance comes into contact with the skin. There are two kinds of contact dermatitis reactions to cosmetics:

• Allergic contact dermatitis. This occurs in people with allergies to one or more ingredients in a cosmetic. The damage occurs because the immune system is reacting to a substance that it considers harmful.
  
  

  

• Irritant contact dermatitis. This is a reaction unrelated to allergies that can occur in anyone. It is the result of contact with a substance that actually breaks down and damages the skin. Symptoms include patches of itchy, scaly skin or a red rash that develops into oozing blisters. Generally, these symptoms appear within minutes or hours of exposure if the substance is strong, or days to weeks in the case of weaker substances. Skin damage usually is confined to the area where the exposure occurred. Thin areas of skin, such as the eyelids, and cracked and dried skin are likely sites for contact dermatitis.

A number of other conditions may be related to the use of cosmetics, including:

• Hives. Red, swollen patches of skin that occur in groups and may burn, sting or itch. Hives may be caused by irritation due to cosmetic use as well as cosmetic allergies.
  

  

• Asthma. A condition in which the airways become blocked or narrowed, causing shortness of breath and difficulty breathing. Cosmetics can trigger asthma symptoms in some people.
  

  

• Allergic conjunctivitis. Inflammation of the tissue lining the inside of the eyelid (conjunctiva) that is caused by an allergic reaction. Conjunctivitis may be caused by allergies, irritation or infection – all of which could potentially be linked to cosmetic use.