How to Perform a Skin Sensitivity Test
The skin sensitivity test can indicate two different things. In the first case it is a medical procedure, the patch test, used to diagnose some contact allergies. In the second case, we refer to a “home” exam to check if you can spread the new product you purchased. In both cases, however, an allergic reaction to an irritant is sought.
Undergo a Cutaneous Allergological Test
1) Learn about the basic principles.
The patch test is used to quantify the allergic response of the skin to contact with particular substances. This is a different test from the prick test.
Through the prick test, reactions are sought to the common allergens that cause symptoms such as urticaria or rhinorrhoea. A nurse scratches or stings the skin to let the potentially irritating substance enter the skin.
The patch test instead reveals the reaction of the skin to the allergen. This reaction is called contact dermatitis.
2) Evaluate your medications with your doctor.
Some active ingredients may alter the result of the patch test. Antihistamines, for example, are designed to suppress the allergic reaction by changing the results of the examination. Your doctor may ask you to discontinue your treatment for a while before undergoing the exam, up to 10 days before the test.
Other medicines that may negatively interact are tricyclic antidepressants, some drugs against acid reflux (such as ranitidine) and omalizumab (an asthma medicine).
3) Be prepared for what will happen.
During the examination, a nurse or the doctor himself prepares a series of small patches, each containing a small amount of different substance known to trigger allergic reactions in some individuals. For example, in some cases, everything is used, from metals such as cobalt and nickel to lanolin and certain plant substances. The patches are applied directly on the back with medical adhesive tape. Generally, the chosen site is the back or the arm.
4) Ask to undergo a photo patch test.
If you often suffer from rashes on the backs of your hands, neck or arms, your skin may react negatively to substances only when exposed to sunlight. To diagnose this problem there is a special examination; if you need a photo patch test, the doctor puts a couple of each substance in contact with the epidermis, exposing only one to the light while the other remains covered.
5) Do not be afraid to feel pain.
Unlike the prick test, this examination does not require the use of needles; as a result, you do not feel any pain when the patches are applied.
6) Keep the area dry.
While keeping the patches in contact with the skin, you should avoid wetting them – this means that you do not have to sweat excessively or expose to high humidity. Do not swim, do not take a shower, do not swim, do not exercise and do not do any activity that could wet the patches.
7) Wait two days.
The patches should generally be left in place for two days; after this time you have to go back to the doctor. The nurse or allergist removes the patches and looks at the skin, to understand which substance has triggered a skin reaction.
The skin may show eruptions that occur as small detected ponphas or fluid-filled sacs.
8) Wait another couple of days.
Sometimes, the doctor wants to see you again, four days after the application of the substances, so you can observe the late reactions to the allergen.
9) Avoid irritants.
When you know the substances that cause you problems, you know what to avoid. Your doctor may advise you not to touch a particular item. In the opposite case, if you do not show any reaction, the doctor will perform further tests to define the causes of the rashes you suffer from.
Test New Products on the Skin
10) Understand the procedure.
When buying a new product, such as a chemical peel or even a simple facial cleanser, it is important to do a skin sensitivity test, especially if you have sensitive skin. In this case, you have to apply a small amount of cosmetic on a small area of the epidermis to observe its reactions.
In other words, you do not have to spread a substance that could trigger a diffuse urticaria all over your face or body; at the beginning it is better to circumscribe the surface.
You should also test the other products in the same way, such as shampoo, conditioner and hair dyes. In practice, if you have a delicate skin, you should do a test with any cosmetic or substance you plan to use.
11) Apply a small amount to the inside of the arm.
This area is perfect for the test, since it is covered with sensitive epidermis. Furthermore, any reaction will not be too visible to other people.
If you experience burning or notice an immediate negative response, wash away the product as quickly as possible.
12) Wait 24 hours.
If you’re testing a lotion, leave it on your skin. If it is a substance, like a chemical peel that needs to be rinsed, remove it once the time indicated on the package has passed. Wait an internal day to see if there are any skin reactions.
If it is, the skin becomes red, swollen or shows a real eruption. It could desquamate or ooze liquids; another symptom is itching.
13) Repeat the test on an even more sensitive area.
Next, you have to try the product on an area of the body where the skin is more delicate. For example, if you’re testing a facial cleanser, apply a small amount behind your ear. The reason for this second test is due to the fact that the ingredients could ignite a more delicate area, but not the inside of the arm.
14) Wait another day.
You have to wait patiently for an internal day in this case, looking for any skin reactions to the substance. If you do not notice any alteration, you can use the product in peace.
The first type of test can help you understand which products you can use for skin care; When you know the substances that irritate the epidermis, you can check that they are not on the list of ingredients in cosmetics.
The second test is suitable for a wide variety of products, including perfumes, makeups, shampoos, deodorants, aftershaves, sunscreens, depilatory creams and other cosmetics that apply directly to the skin.