Causes It is often very difficult to determine the specific cause of an episode of allergic or contact dermatitis. Many people are highly sensitive to specific types of chemicals in foods, cosmetics, medications, and perfumes. Some foods seem to cause hives to a greater extent than others. These include nuts, chocolate, fish, tomatoes, eggs, berries, and milk. Sometimes additives and preservatives in the food may be responsible for the hives.
Hives can also result from physical agents such as vibration, sunlight, cold pressure, and exercise.
Contact dermatitis can be caused by a great number of substances including cleaning chemicals, nickel dust, adhesives, and epoxy resins. The most effective method of dealing with any type of dermatitis risk is through prevention. The substitution of hazardous chemicals with safer materials, whenever possible, will greatly decrease the risk of dermatitis. This may involve modifications in procedures but can often be accomplished through direct substitution. The second line of defense against dermatitis is the use of protective equipment and barrier creams.