I have a pimple in my armpit. it's red, tender & hurts when i touch it. i use birth control so idk if it's causing it & what should i do if it has pus?

Folliculitis: Or skin infection. Hot shower to clean up the area, if you have fever or it doesn't clear up in a day or two, see your doctor. If it has pus, your body is doing its work clearing out this infection.

Common: Pimple/abscess in armpit is common. Moisture, warmth & abundant hair follicles make the area more susceptible. U shd use Advil (ibuprofen) and keep the area clean and dry. Avoid using deodorants and do not cause further trauma by shaving etc. if pain increasing and infection spreading u may need antibiotics- see ur doc. Topical antibiotic like polysporin (OTC) may prevent spread. OCs do not cause this.