Boils are localised infections that lie deep under the skin. There are many different causes of boils, but the most common ones are because of bacterial infections or the inflammation of sweat glands. Boils that develop under the arm are extremely painful and not always easy to treat because of their location. There are a few things you can do at home, however, to treat underarm boils and speed their healing.
Apply heat to the area. Boil some water and steep a washcloth in the hot water. Lift it out with tongs and when it is cool enough, wring out the excess water and place the warm washcloth as a compress on the boil. Leave on until it cools. A hot water bottle can also be used as a warm compress, just be sure to place a towel or washcloth between your skin and the bottle to prevent burning.
Boil 1/2 cup of water and transfer it to glass cup. Add just enough cornmeal to make a paste. Apply to boil and cover with a gauze pad. Repeat every two hours as long as you can, or until the boil comes to a head.
Apply warm boiled egg whites directly to the boil. Cover with a gauze pad. This is a slower remedy that will help draw the pus to a head.
Cut a raw onion into thick slices. Place on top of the boil and cover with a gauze pad. Secure in place with medical tape. Change the onion every 3 hours. Do this until boil comes to a head. Onions are antiseptic and draw circulation to the boil and help draw it to a head for draining.
Wash all washcloths and towels that have touched the boil, as they can spread a bacterial infection if left dirty.
Never squeeze or try to pop a boil before it has come to a head. This can make the boil more painful and even cause the infection to spread further under the skin.