Contact dermatitis is characterized by red and potentially painful inflammation of the skin. The term covers any such inflammation caused by direct contact from a substance to which the skin reacts. Determining and eliminating the cause of contact dermatitis is essential for effective treatment and, in some cases (i.e. contact with caustic chemicals), very serious injury can result if you don’t seek medical attention. Essentially, contact dermatitis boils down to a couple of different categories of causes, each with different reaction times and potential severity.
Direct contact with irritants. According to the U.S. National Library of Medicine, “Irritant dermatitis, the most common type of contact dermatitis, involves inflammation resulting from contact with acids, alkaline materials such as soaps and detergents, solvents, or other chemicals.” This type of contact dermatitis generally appears immediately or within a very short time span after contact. Chemical burns, itching rashes and other such skin issues are common manifestations of contact dermatitis in this case. Only the area that actually came into contact with the irritant will be affected.
Allergic reactions. If you have unexplained rashes, bumps or itchy areas of skin that may or may not have come into contact with a foreign substance, then it is likely allergen-related contact dermatitis. In most cases, allergens will cause a reaction within about 24 hours of direct contact. The reaction may be localized or may be spread over large areas of skin as part of a systemic allergic reaction. Common culprits include plants such as poison ivy, many common weeds and even grass if you have an allergy to it. Mild household chemicals or personal care products may also produce allergic contact dermatitis if you have sensitive skin.
Overtreatment. While the overtreatment form of contact dermatitis deals directly with the skin’s reaction after prolonged exposure to treatments for other skin issues, many substances may cause a reaction after days or weeks of uneventful use. This may include skin creams, sunblock, makeup or other products that come into contact with the skin on a regular basis and that may stay on the skin for extended periods of time. Overtreatment dermatitis is often the most difficult to diagnose because the reaction involves something that previously caused no problems and that you may be able to use again after the skin has had a break.