Folliculitis is one of the most common reasons. It happens when hair follicles get inflamed, which is usually caused by bacteria, sweat, or clogged pores. These bumps can hurt, itch, and sometimes have pus in them.

Acne on the scalp is like acne on the face. It can happen because of too much oil, hair products, or not washing your hair well enough. These breakouts usually show up at the top of the head or along the hairline.

Sometimes, seborrheic dermatitis looks like pimples. People often mistake it for acne because it causes red, scaly patches that don’t go away. It has something to do with yeast on the skin and might need medicated shampoos to get rid of it.

Cysts and boils can also grow on the head. These are deeper and usually hurt more than regular pimples. They can be caused by infections or oil glands that are blocked. If they don’t go away or get worse, a doctor should look at them.