What is Contact Dermatitis?Contact dermatitis is an itchy, blistering skin rash typically caused by the direct contact of a substance with the skin. There are two types of contact dermatitis, irritant and allergic. This difference is often difficult to tell apart, and is not usually an important distinction to make.
Contact dermatitis results in 5.7 million doctor visits each year in the United States, and all ages are affected. Females are slightly more commonly affected than males, and teenagers and middle-aged adults seems to be the most commonly affected age groups.
How Do Sunscreens Work?Sunscreens work in one of two ways:
Chemical Absorbers: Most sunscreens absorb ultraviolvet (UV) radiation (the energy from the rays of the sun) and turn this energy into a less dangerous form of radiation that causes less damage to the skin. There are sunscreens that absorb different types of UV radiation, such as UVA and UVB. Chemical absorbers include most of the available sunscreens that can be rubbed completely into the skin.
Physical Blockers: These sunscreens reflect the sun’s radiation away from the skin, so that it is not absorbed. Physical blockers include zinc oxide, the brightly colored sunscreens frequently used on the nose and lips of beachgoers.
What is Sunscreen Allergy?While contact dermatitis to sunscreens is not as common as allergy to cosmetics, it is not a rare condition. The reaction to sunscreens can occur anywhere the substance is applied on the body, although tends to be more common on the areas of the body with the most exposure to the sun. This is called “photo-contact dermatitis.”
Photo-contact dermatitis usually occurs in a sun-exposed pattern on the body. These areas would include the face (but not the eyelids), the “V” area of the upper chest and lower neck, the backs of the hands and the forearms. The area of the neck under the chin is usually not affected.
Contact dermatitis to sunscreens can occur as a result of allergy to the active ingredients or to the fragrances and preservatives present in the product.
Find out about patch testing, an important part of the evaluation of contact dermatitis.
Who is at Risk for Developing Sunscreen Allergy?Those most at-risk for developing sunscreen allergy include the following groups:
- Females, possibly as a result of higher use of cosmetics containing sunscreens
- People with chronic sun-related skin conditions, such as sun-damaged skin
- People with atopic dermatitis
- People who have applied sunscreens to damaged skin
- People with outdoor occupations
Which Chemicals in Sunscreens Cause Allergies?Many active ingredients are present in sunscreens that cause contact dermatitis. Some of these chemicals cause more problems than the others. Many sunscreens have multiple active ingredients, so it may be difficult to determine the exact cause without patch testing for the individual chemicals. The following are the most common active ingredients in sunscreens reported to cause contact dermatitis.
Para-Aminobenzoic Acid (PABA). PABA was one of the earliest ingredients used in sunscreens, but now is rarely used due to the many side effects of this chemical, including contact dermatitis and its tendency to stain clothing. A number of chemicals related to PABA still used today, including padimate A and O. Many sunscreens are falsely labeled “hypo-allergenic” since they do not contain PABA, but can still cause contact dermatitis from other active ingredients.
Benzophenones. Benzophenones have been used in sunscreens for 50 years, and are one of the most common causes of sunscreen-induced contact dermatitis in the United States. Other names for benzophenones include oxybenzone, Eusolex 4360, methanone, Uvinal M40, diphenylketone and any other chemical name ending with “-benzophenone”.
Cinnamates. Cinnamates are less commonly found in sunscreens but are a common ingredient used as flavorings and fragrances in everything from toothpaste to perfumes. These chemicals are related to Balsam of Peru, cinnamon oils and cinnamic acid and aldehyde, so people allergic to cinnamates may also be allergic to these other chemicals.
Other names of cinnamate containing chemicals include Parsol MCX and any chemical ending with “–cinnamate.”
Salicylates. Benzyl salicylate was the first sunscreen used in the United States. Common chemicals in this group used today include octyl salicylate, homosalate and any chemical ending with “-salicylate.” Salicylates are rare causes of contact dermatitis.
Dibenzoylmethanes. These sunscreens have been used in the United States since 1997, and include the chemicals avobenzone and Eusolex 8020. They are frequently combined with other chemical absorbers in sunscreens.
Octocrylene. Octocrylene is a relatively new chemical used in sunscreens, but has been reported to cause contact dermatitis. It is similar to cinnamates, and may be used together with cinnamate chemicals in sunscreens.
Don't miss page 2: What sunscreens can I use if I have a sunscreen allergy?