Pus in the armpit is caused by a bacterial infection. Bacteria can enter the body from broken skin related to shaving or other means of hair removal. To minimize the risk of broken skin in the armpit area, using an electric razor instead of a straight razor is often recommended. Using chemical depilatory products can also cause breaks in the skin because of the irritation that they cause. Boils and carbuncles can also cause an infection and subsequent pus in the armpit.

A boil or cyst accompanied by pus in the armpit should never be squeezed, lanced, or handled excessively. Disturbing pus in the armpit can aggravate the infection and even cause the infection to spread. Other symptoms of an infection in the armpit include pain, swelling, and redness. The color of pus in the armpit can vary, and can range from white to yellow or green. Blood may also be present in the pus, although it typically causes the pus to turn pink, instead of bright red. When an armpit infection occurs, a health care provider needs to be consulted for evaluation and treatment recommendations.

Sometimes, the health care provider may decide to lance the boil to relieve the pus. This should only be done in a medical setting and should never be attempted in the home. After the health care provider lances the boil or cyst, a topical antibiotic ointment is usually applied and then covered with a sterile dressing. Oral antibiotics may also be prescribed to treat the infection and reduce the risk of a secondary infection.

If the wound has been lanced, products such as antiperspirants, deodorants, powders, or depilatories should be avoided to reduce the risk of further irritation. Sometimes, an armpit infection can spread to other parts of the body, including the blood stream. Symptoms of a blood infection include fever, chills, body aches, and headache. In addition, fatigue, nausea, vomiting, and dizziness can occur.

An infection that causes pus in the armpit is referred to as a purulent infection and typically responds to antibiotic therapy. The entire antibiotic prescription needs to be finished to make sure the infection goes away. Sometimes, however, antibiotics can cause such severe side effects that they cause the patient to stop taking them. Side effects of antibiotics include stomach pain, nausea, and diarrhea. If these side effects occur, the health care provider can treat the side effects or prescribe a different antibiotic less likely to cause side effects.