Anxiety, hormones, and armpit hair can turn your sweat sour. Wildly overactive sweat glands (hyperhidrosis) can also cause underarm odor. Most folks need deodorants, not antiperspirants, but if you really suffer from armpit odor, try a boric acid or tannic acid solution. Still dripping? Put on 20% aluminum at night and wash it off in the morning, or try antibiotic creams to kill multiplying bacteria. If you have hyperhidrosis, Botox turns off the faucet. Beta-blockers (high blood pressure medication) can help relieve chronic, stress-related sweating.