There is no “good” type of psoriasis to have. But if you’ve got psoriatic plaques hidden in the folds of your skin, rubbing every time you move, creating additional friction and discomfort, you know that inverse psoriasis can be among the most painful kinds.

According to the National Psoriasis Foundation, it’s not uncommon for people with inverse psoriasis to also have other types of psoriasis elsewhere on the body. But what, exactly, constitutes inverse psoriasis—and how can you treat it? Here are all the basics you should know.

What Is Inverse Psoriasis?

While inverse psoriasis typically presents in conjunction with other forms of psoriasis, it is defined primarily by where on the body it is found: in creases, where skin rubs on skin. “Inverse psoriasis presents as red plaques, or as a shiny smooth rash, confined to the folds of the body,” explains board-certified dermatologist Peterson Pierre, M.D., of Pierre Skin Care Institute in Westlake Village, California.