When it comes to skin care, you can’t always be sure a product will work for you, especially if you have sensitive skin. While completing a skin patch test isn’t necessary for most, if you struggle with sensitivities and allergies, patch testing might be a very rough guide as to whether or not your skin can tolerate a particular product.

What is a Skin Patch Test?

A skin patch test uses a small patch of skin to test new skin care products or ingredients. Patch tests can be done anywhere on the body, but the most common places are the underside of the jaw, behind the ear, side of the neck, crease of the elbow, back of the hand or the inside of the wrist.

If you have sensitive skin and you’re concerned about a product affecting you, simply apply the product to an inconspicuous area and wait for 24 hours. Did your skin react? If so, you might want to avoid applying the product to your entire face. If not, try patch testing in another area before you apply to your entire face. Dr. Joel Schlessinger, board-certified dermatologist and LovelySkin CEO, says:

“Certain areas are not a great match for products, though they can work well elsewhere. Something that works fine on the face or arm may be awful for the neck or eyes. If you are typically allergic or sensitive to many ingredients, it may be helpful to find out what is causing these reactions by doing an in-office patch test with your dermatologist.”

An in-office skin patch test, which involves a dermatologist testing your skin’s reaction to common allergens like parabens, synthetic fragrances and dyes or preservatives, tends to be much more reliable than an at-home patch test, but it can also be quite expensive ($1000 and upward depending on how many items are tested). These types of tests are typically done on the back, and are a much more effective way to pinpoint which ingredients might be irritating your skin.

Why Should I Patch Test Skin Care?

Whether you patch test your skin care products or not is up to you, but it’s only really necessary when you have known sensitivities or allergies. In these cases, a patch test can help you avoid irritation and unwanted side effects. We asked Dr. Schlessinger for his take on the best ways to patch test skin care:

“Patch testing at home is something that can be attempted, but often is just a rough guide. It doesn't actually solve the issue as the product itself contains so many individual ingredients, and it can be difficult to narrow down the cause of the reaction. If there is a reaction, it could be to one or many ingredients and the next product could have the same issues. For this reason, while it is a reasonable idea, it isn't always practical.”

If you happen to have a reaction to your skin care, ask your dermatologist to do an in-office patch test. Dr. Joel Schlessinger recommends this method to ensure you pinpoint which ingredients are causing the reaction:

“Patch testing can be an excellent way to determine allergies to commonly used ingredients in products. While it is helpful, there is a limit to how many actual ingredients can be tested as it involves placing patches on the back and then waiting 48 hours to see if any reaction ensues. These patches are long, rectangular strips that contain 10 potential allergy-causing ingredients. The size of the back generally limits us to no more than about 80-100 at maximum.

We generally test for up to 80 of the most common 'allergens' (potential allergy-causing ingredients) in our tests, but keep in mind that there are millions of actual causes and we can only test for those that are most common. Having said this, it is extremely helpful in many cases!”

Have you ever been patch tested? Let us know what you found out in the comments below!