Symptoms and causes

Symptoms

Contact dermatitis usually occurs on areas of your body that have been directly exposed to the reaction-causing substance — for example, along a calf that brushed against poison ivy or under a watchband. The rash usually develops within minutes to hours of exposure and can last two to four weeks.

Signs and symptoms of contact dermatitis include:

  • A red rash
  • Itching, which may be severe
  • Dry, cracked, scaly skin
  • Bumps and blisters, sometimes with oozing and crusting
  • Swelling, burning or tenderness

When to see a doctor

See your doctor if:

  • The rash is so uncomfortable that you are losing sleep or are distracted from your daily activities
  • The rash is sudden, painful, severe or widespread
  • You're embarrassed by the way your skin looks
  • The rash doesn't get better within three weeks
  • The rash affects your face or genitals

Seek immediate medical care in the following situations:

  • You think your skin is infected. Clues include fever and pus oozing from blisters.
  • Your lungs, eyes or nasal passages are painful and inflamed, perhaps from inhaling an allergen.
  • You think the rash has damaged the mucous lining of your mouth and digestive tract.

Causes

Contact dermatitis is caused by a substance you're exposed to that irritates your skin or triggers an allergic reaction. The substance could be one of thousands of known allergens and irritants. Some of these substances may cause both irritant contact dermatitis and allergic contact dermatitis.

Irritant contact dermatitis is the most common type. This nonallergic skin reaction occurs when a substance damages your skin's outer protective layer.

Some people react to strong irritants after a single exposure. Others may develop signs and symptoms after repeated exposures to even mild irritants. And some people develop a tolerance to the substance over time.

Common irritants include:

  • Solvents
  • Rubbing alcohol
  • Bleach and detergents
  • Shampoos, permanent wave solutions
  • Airborne substances, such as sawdust or wool dust
  • Plants
  • Fertilizers and pesticides

Allergic contact dermatitis occurs when a substance to which you're sensitive (allergen) triggers an immune reaction in your skin. It usually affects only the area that came into contact with the allergen. But it may be triggered by something that enters your body through foods, flavorings, medicine, or medical or dental procedures (systemic contact dermatitis).

You may become sensitized to a strong allergen such as poison ivy after a single exposure. Weaker allergens may require multiple exposures over several years to trigger an allergy. Once you develop an allergy to a substance, even a small amount of it can cause a reaction.

Common allergens include:

  • Nickel, which is used in jewelry, buckles and many other items
  • Medications, such as antibiotic creams and oral antihistamines
  • Balsam of Peru, which is used in many products, such as perfumes, cosmetics, mouth rinses and flavorings
  • Formaldehyde, which is in preservatives, disinfectants and clothing
  • Personal care products, such as deodorants, body washes, hair dyes, cosmetics and nail polish
  • Plants such as poison ivy and mango, which contain a highly allergenic substance called urushiol
  • Airborne substances, such as ragweed pollen and spray insecticides
  • Products that cause a reaction when you're in the sun (photoallergic contact dermatitis), such as some sunscreens and oral medications

Children develop the condition from the usual offenders and also from exposure to diapers, baby wipes, sunscreens, clothing with snaps or dyes, and so on.

Risk factors

Some jobs and hobbies put you at higher risk of contact dermatitis. Examples include:

  • Health care and dental employees
  • Metalworkers
  • Construction workers
  • Hairdressers and cosmetologists
  • Auto mechanics
  • Scuba divers or swimmers, due to the rubber in face masks or goggles
  • Cleaners
  • Gardeners and agricultural workers
  • Cooks and others who work with food

Complications

Contact dermatitis can lead to an infection if you repeatedly scratch the affected area, causing it to become wet and oozing. This creates a good place for bacteria or fungi to grow and may cause an infection.

July 07, 2017
References
  1. Goldner R, et al. Irritant contact dermatitis in adults. https://www.uptodate.com/home. Accessed April 27, 2017.
  2. Goldsmith LA, et al., eds. Allergic contact dermatitis. In: Fitzpatrick's Dermatology in General Medicine. 8th ed. New York, N.Y.: The McGraw-Hill Companies; 2012. http://www.accessmedicine.mhmedical.com. Accessed April 27, 2017.
  3. Contact dermatitis. Merck Manual Professional Version. https:/www.merckmanuals.com/professional/dermatologic-disorders/dermatitis/contact-dermatitis. Accessed April 27, 2017.
  4. AskMayoExpert. Contact dermatitis. Rochester, Minn.: Mayo Foundation for Medical Education and Research, 2016.
  5. AskMayoExpert. Poison ivy rash. Rochester, Minn.: Mayo Foundation for Medical Education and Research, 2016.
  6. Fonacier L, et al. Contact dermatitis: A practice parameter — Update 2015. Journal of Allergy and Clinical Immunology Practice. 2015;3(3 suppl):S1.
  7. Gibson LE (expert opinion). Mayo Clinic, Rochester, Minn. May 7, 2017.