A patch test on the skin can mean two different things. First, the doctor does a patch test on your skin for a specific allergen. Second, a patch test is conducted to test the newly purchased product whether it is safe to use on the skin. Both test for allergic reactions to allergenic substances.
Step
Method 1 of 2: Performing a Skin Allergy Test
Step 1. Understand the basics of testing
Patch testing is used to test for allergic reactions to contact with a substance or substances. The patch test is different from the prick or scratch test.
- The scratch test checks for reactions to common allergens that may cause symptoms ranging from hives to runny nose. The nurse will scratch or prick the skin to extract allergens from the skin.
- The patch test only checks the skin's reaction to the allergen. The skin reaction to an allergen is called contact dermatitis.
Step 2. Discuss treatment with your doctor
Certain medications can affect the patch test. For example, antihistamines are designed to suppress an allergic reaction, which would alter patch test results. Your doctor may tell you to stop using these medications for a while before testing is done (about 10 days in advance).
Other medications that interfere with patch testing are tricyclic antidepressants, some medications for acid reflux (eg ranitidine), and omalizumab (an asthma medication)
Step 3. Be prepared for things to come
During the patch test, the doctor or nurse will apply a series of small patches. Each patch contains a small amount of a substance known to cause allergies. For example, some patch tests use substances ranging from metals such as cobalt and nickel to lanolin and certain plant species. This patch will be attached to the skin with a medical tape. Usually the patch is placed on the back of the arm.
Step 4. Ask about photo-patch testing
If you often get a rash on the back of your hands, neck, or arms, your skin may react only to sunlight. In this case, a special test was carried out. If you need a photo-paste test, the doctor will place two of each substance and expose one of them to light, the other not.
Step 5. Don't be afraid to feel pain
In fact, unlike the scratch test, the patch test does not use a needle. Hence, there will be no pain during patch testing.
Step 6. Keep the test area dry
While still attached, try not to get the plaster wet. This means that you should avoid extreme heat and humidity and sweat profusely. Avoid swimming, bathing, and exercising to prevent getting wet.
Step 7. Wait two days
After two days, go back to the doctor. The nurse or doctor will take the patch from the skin and see the results. Skin that reacts to one of the patches indicates the substance to which you are allergen.
The skin reaction may appear as a rash, possibly with small, raised, pimple-like areas or fluid-filled sacs
Step 8. Wait two more days
Sometimes, your doctor will tell you to come back within four days of the initial test. This step is done to see delayed reactions to allergens.
Step 9. Avoid allergens
Once you know the substance causing the allergy, stay away from the allergen. Your doctor will give you advice on avoiding certain allergens. On the other hand, if the test returns nothing, the doctor will look for other causes of the rash.
Method 2 of 2: Testing a new Product on the Skin
Step 1. Understand testing new products on the skin
When buying a new product, such as a chemical peel or simply a facial cleanser, it's important to test the product on your skin first, especially if you have sensitive skin. Patch test is done by giving a small amount of product on the skin and seeing the reaction.
- In other words, you don't rub the product all over your body or face and cause itching everywhere. First of all, it's best to limit the area where your product is used.
- It's also a good idea to test other products, such as shampoo, conditioner, and hair dye. Basically, if you have sensitive skin, test all products that touch your skin.
Step 2. Apply a small amount of the product under test on the inner arm
The inner arm is a good test site because the skin is quite sensitive. In addition, the reactions that may arise will not be seen too clearly.
If the product burns or causes an immediate reaction, wash it off as soon as possible
Step 3. Wait for 24 hours
If the product being tested is like a lotion, leave it on your skin. If the product being tested is like a chemical peeler, rinse it off in time. Wait a full day for a reaction.
Reactions that appear can be in the form of reddened skin, welts, or a rash appears. The skin may also become scaly or slimy. Another symptom is itching
Step 4. Test on a more sensitive area
Next, move on to a more sensitive area. This time, select the area where the product will be used. For example, if you use a facial cleanser, try doing an under-ear test. The reason for retesting is that the allergen may act on a more sensitive area even if it doesn't react on your arm.
Step 5. Wait one day
Again, wait a day to see how the product reacts to the skin. If no reaction occurs, the product is safe to use.
Tips
- The first patch test can help you determine the substance that can be applied to the skin. If you already know your allergen, look for the substance in the ingredients of beauty products.
- The second test was conducted on a wide variety of products, including perfumes, makeup, shampoos, deodorants, post-shave products, sunscreens, depilatory creams, and other cosmetic products that come into direct contact with the skin.
