A boil is a localized infection deep in the skin. A boil generally starts as a reddened, tender area. Over time, the area becomes firm, hard, and tender. Eventually, the center of the boil softens and becomes filled with infection-fighting white blood cells from the bloodstream to eradicate the infection. This collection of white blood cells, bacteria, and proteins is known as pus. Finally, the pus "forms a head," which can be surgically opened or spontaneously drain out through the surface of the skin. Pus enclosed within tissue is referred to as an abscess. A boil is also referred to as a skin abscess.

Hot compresses with essential oils can be used to 'draw out' a boil and speed healing, the most suitable being Bergamot and Lavender because of their antiseptic properties, though Camomile is useful, too. The whole area around the boil should be washed several times a day with a 1% to 3% dilution of Lavender or Bergamot.

A person suffering from boils, especially if they are numerous or recur frequently, needs help in reducing the level of toxicity in the body, and regular massage and/or baths, using purifying and detoxifying oils such as Juniper, Lavender or Bergamot are valuable. Garlic perles taken daily will help with the detoxifying process, and so will herbal teas or infusions, particularly fennel and nettle. Dietary advice may be needed, particularly to guide the sufferer away from over-refined foods, and towards a diet high in raw and fresh fruit and vegetables. Vitamin and mineral supplements may be needed until the body returns to normal.

Boils often appear when a person's resistance has been lowered by illness or stress, and other essential oils and treatments might be needed to help with this state of lowered vitality that has contributed to the outbreak of boils.