You may think of psoriasis as being pretty straightforward—you’d know it when you saw it, right? But psoriasis doesn’t always present the same way or show up in the same places.

About 7.5 million people in the U.S. have psoriasis, according to the American Academy of Dermatology. People who suffer from psoriasis can have flare-ups that cause the characteristic red, itchy, scaly skin patches to show up on their skin. And it can show up wherever you have skin. “Psoriasis can appear anywhere—on the eyelids, ears, mouth and lips, skin folds, hands and feet, and nails,” Michael Siegel, Ph.D., vice president of research programs at the National Psoriasis Foundation, tells SELF. “The skin at each of these sites is different and requires different treatments.”

“The impact of psoriasis ranges from annoying to life-altering depending on the location and the extent of the disease,” Cynthia Bailey, M.D., a diplomate of the American Board of Dermatology and president and CEO of Advanced Skin Care and Dermatology, tells SELF. And, as you can imagine, it can have an impact on your self esteem. “I have young women who have just a few patches on their legs and won’t wear shorts or skirts because they’re embarrassed by it,” New York City dermatologist Doris Day, M.D., tells SELF. “They say people think they’re contagious.”

For the record, psoriasis isn’t contagious—it’s caused by a combination of genetics and environmental triggers like stress, sunburn, allergies, diet, certain medications (including lithium and the heart medication quinidine), and even the weather, per the National Psoriasis Foundation.

There are different types of psoriasis and, while Siegel says you can have any type of psoriasis in any part of your body, some are more likely to show up in certain places than others. Here are the most common places psoriasis appears on the body, and what you should look out for at each site: