As board-certified dermatologist Ava Shamban, M.D., founder of SKINFIVE previously told mbg, hydrocolloid is a special type of wound dressing that “heals and acts like a vacuum for your skin.”

See, the hydrocolloid material absorbs excess fluid, like oil and pus, without drying out the skin. That’s why the spot tends to turn white underneath the covering—it’s from all the pus and gunk accumulating under the patch without any air. 

Not to mention, the covering can keep you from picking and prodding at your pimples, which can speed up healing time. 

As hydrocolloid patches become more popular, brands have even infused them with extra acne-fighting ingredients, like tea tree or salicylic acid. “Most pimple patches are made with a hydrocolloid material, and sometimes another active ingredient such as salicylic acid will be added to the material to help speed the treatment and healing of pimples,” notes board-certified dermatologist Rebecca Marcus, M.D., founder of MaeiMD.

Different patches will be best suited for different types of acne; below, you’ll find the best of the best for every type of spot.