A pimple is a result of a blockage of the skin's pore. It can be a pustule or papule.
Inside the pore are sebaceous glands
which produce sebum
. When the outer layers of skin shed (as they do continuously), the dead skin cells left behind may become 'glued' together by the sebum. This causes a blockage in the pore, especially when the skin becomes thicker at puberty
. The sebaceous glands produce more sebum which builds up behind the blockage, and this sebum harbours various bacteria
including the species Propionibacterium acnes
. Pimples can often be caused by stress.
Common over-the-counter medications
for pimples are benzoyl peroxide
and/or salicylic acid
. Both medications can be found in many creams and gels used to treat acne through topical application. Both medications help skin slough off more easily, which helps to remove bacteria faster. A regimen of keeping the affected skin area clean plus the regular application of these topical medications is usually enough to keep acne under control, if not at bay altogether. 1-2% of the population is allergic to benzoyl peroxide treatments.
Severe acne usually indicates the necessity of prescription medication to treat pimples. Prescription medications used to treat acne include isotretinoin
, which is a retinoid
. Historically, antibiotics
such as tetracyclines
were prescribed. While they were more effective than topical applications of benzoyl peroxide, the bacteria eventually grew resistant to the antibiotics and the treatments became less and less effective. Also, antibiotics had more side effects than topical applications, such as stomach cramps and severe discoloration of teeth.