A woman touching her skin.

There’s a distinct thrill that comes with ripping off the packaging of a brand new beauty purchase—whether it’s a jar of cream, a bottle of serum, or whatever skin care product you’ve been jonesing for—and slathering it on for the very first time. But before you do, here’s a quick reminder why patience is a virtue, especially when it comes to skin care: There’s always a chance that a new product may cause an adverse reaction on your skin (think: redness, itching, or swelling) so it’s best to patch test every single skin care product before really using it. 

What’s a patch test, exactly?

Simply put, a patch test means applying a small amount of product on a tiny area of skin—preferably somewhere discreet, like behind your ears or on the inside of your arms—and leaving it on for 24 hours or more. The purpose of this is to check if your skin will develop any signs of irritation or an allergic reaction from the product or any of its ingredients, potentially saving you from more serious (and angry!) skin issues.

Doing a patch test lets you see how your skin will react to the product.

But while patch testing is obviously crucial for those with sensitive skin or a history of product-caused flare-ups, it’s also recommended for those with well-balanced skin types as certain formulas or components can irritate even seemingly resilient complexions. This is because some products may contain allergens that can cause “allergic contact dermatitis,” usually characterized by a red itchy rash.

In some cases, your skin may simply not like a specific ingredient in your product, whether it’s natural or not. And then there are those ingredients that are known for being more likely to cause a reaction, such as fragrances, synthetic dyes, parabens, preservatives, and sulfates.

A quick note, though: There are some products, like acid-based skincare, that are meant to cause a skin reaction in order to be effective. This includes formulas with alpha hydroxy acids, like glycolic acid, and beta hydroxy acids, such as salicylic acid. These products (as well as those with retinol) usually cause a mild tingling sensation as it triggers exfoliation. That said, the slight discomfort is normal and often short-lived. If it worsens over time, though, it may be best to discontinue use.

How to do a patch test

The best area to do the patch test is somewhere close to where the product is really supposed to be applied. So if it’s a face product, you can test behind your ear or on the side of your neck. For body products, you can test on the inner arms or behind the knee. Get a dollop of product and apply it on a small area of clean, dry skin.

Allergic reactions typically appear after around 24 hours so monitor closely for any signs of irritation or discomfort. If irritation does appear, wash off the area immediately—and say goodbye to your new product. (Sorry!)

When doing a patch test, choose an area that you can easily hide in case of negative reactions.

On the other hand, patch testing for breakouts may take several days up to a week. Apply a small amount of product on the side of the cheek or chin—areas that are normally prone to pimples—and re-apply on the same area every day for about a week. If you break out, then your product is likely not a good fit. But if you don’t, then you can very well welcome it to your

Basically, there are two types of reactions to watch out for when testing your products. First is an allergic reaction that’s akin to skin irritation, which simply means the formula or an ingredient in it is not a match for you. Symptoms include redness, rashes, itching, and swelling or inflammation of the area. The second type of reaction? The formation of pimples or breakouts, which results from a bad chemical reaction or incompatibility with your skin.

Skin safety tips

Ready to do your patch tests? Heed these additional reminders for your own safety:

Watch out for severe reactions.

If you experience severe itching, burning, or swelling, thoroughly wash off the area and take an antihistamine to counteract the allergic reaction. You may also want to consult with your doctor.

Soothe irritated skin safely.

A cold compress can help relieve itching and rashes. You can also apply a soothing product like Vaseline Petroleum Jelly, which helps heal stressed or sensitive skin while delivering moisture.

Give skin extra TLC.

When in doubt, opt for gentle, hypoallergenic products made with non-irritating ingredients. Try Dove Body Wash for Sensitive Skin, which is specially formulated to nourish and care for delicate skin.

Sure, it’s always exciting to try a new beauty find, especially when you already have it in your hands, ready for slathering. But for your skin’s sake (and to save yourself from unnecessary drama), remember that a little testing—and a little waiting—can go a long way. Have fun!