Not washing the hair regularly and thoroughly, wearing tight headgear, and build-up of hair products on the scalp are some causes of scalp pimples. Scalp pimples can develop in the form of pimples, blackheads, whiteheads, pustules, or nodules on the scalp as well as at the back of the head. Yeast, bacteria and mites can worsen the situation by entering into the pores and causing a reaction. Germs like Malassezia yeast, Staphylococcus aureus, Demodex folliculorum, and curtobacterium can cause severe scalp pimples. Stress, hormonal balances, certain foods, and abnormal immune responses can all be contributing factors for the appearance of these pimples.

Ref: NewsDeal