Offering Expertise in Diagnosis of Skin RashesWatch to Learn About Patch Testing and Contact Dermatitis Show
What is patch testing?Allergic contact dermatitis occurs when your skin comes into contact with a substance that causes you to have a reaction. Patch testing is designed to identify substances that may be causing your skin rash. During patch testing, substances to which you may be allergic are applied to your back. Your skin is then examined for allergic reactions. Patch testing does not involve scratches or pricks to the skin. It does not identify allergies to food, oral medications or inhaled substances. How do I prepare for patch testing? You may continue to use moisturizers until the patch-test strips are applied. Avoid exposure to the sun or ultraviolet light (such as tanning booths) for four weeks before patch testing. On the day you are scheduled to have your patches applied, you may wish to wear clothes you won't mind getting stained. On rare occasions, the pen used to mark the area to be tested can stain clothing. How is patch testing done?Patch testing involves a series of appointments, each lasting about 20 minutes. These appointments will be scheduled with the patch test nurse.
What do my results mean?Positive Results — If patch testing reveals you are allergic to a substance or substances, the test is "positive." You will be given information about the substance or substances that caused your skin to react, including alternate names for them and the products in which they may be found. Examining the products you use can help you avoid substances to which you are allergic. Remember: Even if you have a positive result, it can be hard to determine exactly what product is causing your reaction and whether other factors also are involved. It may take time to lessen or eliminate your symptoms. Be patient and continue to work with your health care provider to determine the best ways to manage your condition. Negative Results — If your skin shows no reaction to patch testing, your results are negative. This may occur when an allergy is not the cause of your skin problems or when the exact chemical causing the problem has not been tested. Retesting of additional chemicals is sometimes needed. Side effects and risksAlthough patch testing can cause a reaction at the patch-test site, the test has very few risks or side effects. You may have itching at the patch-test site after testing is completed, but this typically goes away within a few days. Contact your health care provider promptly if a disk causes intense itching, burning or pain. SLUCare patch testing providerDr. Nicole Burkemper Locations offering patch testingCenter for Specialized Medicine1225 South GrandSt. Louis, MO 63104314-977-3400 314-977-9721 OverviewWhat is contact dermatitis?Dermatitis is the medical term for skin inflammation (irritation). Contact dermatitis is an allergic or irritant reaction that causes a painful or itchy skin rash. As the name suggests, you get contact dermatitis from coming into contact with an allergen (like poison ivy) or an irritant (like a chemical). How common is contact dermatitis?The condition is common. We are surrounded by irritants and potential allergens. You might experience contact dermatitis more often if you have sensitive skin or other chronic skin problems like atopic dermatitis. Who might get contact dermatitis?Irritant reactions can occur after a single exposure or after repeated exposures over time, whereas it takes multiple exposures to the same chemical to develop an allergy. People who work in certain professions have a higher risk of developing contact dermatitis. You might repeatedly encounter irritating chemicals or allergens in these professions:
What are the types of contact dermatitis?The two main types of contact dermatitis are: Allergic contact dermatitis: Your body has an allergic reaction to a substance (allergen) that it doesn’t like. Common allergens include jewelry metals (like nickel), cosmetic products, fragrances and preservatives. It can take several days after exposure for an itchy, red rash to develop. Irritant contact dermatitis: This painful rash tends to come on quickly in response to an irritating substance. Common irritants include detergents, soap, cleaners and acid. Symptoms and CausesWhat causes allergic contact dermatitis?Every time your skin comes into contact with an allergen that it doesn’t like, your body’s immune system responds. White blood cells are recruited into the skin, releasing chemical mediators of inflammation. This response causes the itchy rash. The rash may appear minutes, hours or several days after exposure. Poison ivy is a top cause of allergic contact dermatitis. Other causes include:
What causes irritant contact dermatitis?Irritant contact dermatitis occurs more often than allergic contact dermatitis. You develop a rash when a chemical substance irritates the skin’s outer layers. The rash is more painful than itchy. Common causes of irritant contact dermatitis include:
What are the symptoms of contact dermatitis?Signs of contact dermatitis include a skin rash that is:
What should I do if I develop contact dermatitis on the job?If you’re regularly exposed to irritating chemicals or allergens at work and develop contact dermatitis, ask your employer for a chemical Safety Data Sheet. You can take this information to your healthcare provider to help determine what’s causing the rash. Diagnosis and TestsHow is contact dermatitis diagnosed?Clinical examination can reveal clues to the underlying diagnosis of irritant or allergic contact dermatitis. A careful history can uncover clues as to the offending agent. With either type of contact dermatitis, you can avoid the substance for a while to see if the rash goes away. If avoidance is not possible or not sustainable, further diagnostic testing may be indicated. For suspected cases of allergic contact dermatitis, a series of tests called patch testing can identify the underlying cause of allergic contact dermatitis. With a patch test, you wear adhesive patches on your skin. The patches contain chemicals known to commonly trigger allergic reactions. After 48 hours, your healthcare provider checks your skin for reactions. You’ll see your provider again in another 48-96 hours for one last skin check. There isn’t a test for irritant contact dermatitis. Your healthcare provider may be able to determine what’s causing the rash based on the types of irritants or chemicals you’re exposed to regularly. Management and TreatmentHow is contact dermatitis managed or treated?Treatment for both types of contact dermatitis is the same. Even with treatment, it can take several weeks for the rash to go away. Treatments include:
What are the complications of contact dermatitis?Allergic contact dermatitis is a Type IV hypersensitivity reaction, caused by a different immunologic mechanism than hives, angioedema, or anaphylaxis. However, very rarely, patients may have immunologic dysfunction which results in multiple types of concurrent hypersensitivity reactions. Thus, it is possible that people with contact dermatitis can develop hives (urticaria) and swelling (angioedema) after coming into contact with an allergen. Hives are red, raised, itchy skin welts. Angioedema is swelling deep under the skin. Extremely rare, allergic contact dermatitis can overlap with a severe, life-threatening allergic reaction called anaphylaxis that can swell airways and close them. If you think you are experiencing anaphylaxis, call 911. You’ll need an immediate epinephrine injection to counteract this allergic response. People with known allergies can carry an EpiPen®, a brand of injectable epinephrine. PreventionHow can I prevent contact dermatitis?Avoiding known allergens and irritants is the best way to prevent contact dermatitis. But you can’t always stay away from every possible irritant. These steps can help:
Outlook / PrognosisWhat is the prognosis (outlook) for people with contact dermatitis?If you’ve reacted to an allergen or irritant, you will continue to do so every time you’re exposed to it again. You can prevent flare-ups by avoiding that substance. Most people who have occupational contact dermatitis can find ways to reduce exposure so they can continue their work without breaking out in a rash. Living WithWhen should I call the doctor?You should call your healthcare provider if the skin rash:
What questions should I ask my doctor?If you’re experiencing signs of contact dermatitis, talk to your healthcare provider. You may want to ask:
Contact dermatitis is uncomfortable and can be painful or itchy. Talk to your healthcare provider about how you can find out what’s causing it, reduce your exposure and prevent reactions. You might develop contact dermatitis from working with irritants or chemicals. Ask your employer about how you can minimize rashes while remaining on the job. What type of test is used to identify the allergen of contact dermatitis?Patch test
Patch testing is generally done to see whether a particular substance is causing allergic skin inflammation (contact dermatitis). Patch tests can detect delayed allergic reactions, which can take several days to develop.
How can you identify contact dermatitis?Signs and symptoms of contact dermatitis vary widely and may include:. An itchy rash.. Leathery patches that are darker than usual (hyperpigmented), typically on brown or Black skin.. Dry, cracked, scaly skin, typically on white skin.. Bumps and blisters, sometimes with oozing and crusting.. Swelling, burning or tenderness.. What test helps identify allergens?Both blood and skin allergy tests can detect a patient's sensitivity to common inhalants like pollen and dust mites or to medicines, certain foods, latex, venom, or other substances. Skin testing is the preferred method used by trained allergists, and is usually the most accurate.
Which test is the most reliable one for allergic contact dermatitis?The Skin Prick Test (SPT) is the most common type of allergy test doctors use to diagnose allergies. Skin tests can be the most accurate and least expensive way to confirm allergens.
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Which of the following tests is used to identify allergens causing contact dermatitis?
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