Boils usually do not mean your body is lacking a specific vitamin or mineral. They are most often caused by a bacterial infection in a hair follicle, commonly involving Staphylococcus aureus, and many people who get an occasional boil are otherwise healthy.
When boils keep coming back, certain factors may make them more likely, such as diabetes, obesity, smoking, malnutrition, anemia, iron deficiency, weakened immunity, or skin conditions like atopic dermatitis. However, recurrent boils alone do not prove that you have an iron or vitamin deficiency. They can also be related to carrying staph bacteria on the skin or in the nose, including MRSA, or to bacteria spreading between household members.
Recurrent lumps in the armpits, groin or under the breasts may not be boils, but a chronic condition called hidradenitis suppurativa, which needs specific treatment.
To help a boil heal, apply a warm compress several times a day, which can help it drain on its own. Avoid squeezing or popping it, and do not share towels, razors or other personal items.
See a doctor or dermatologist if boils keep returning, appear in clusters, are on the face, are very large or painful, do not improve, or occur with fever, chills or spreading redness. People with diabetes or weakened immunity should see a doctor sooner. For recurrent boils, a doctor may recommend treatment to remove staph bacteria from the skin and nose. Avoid taking iron, high-dose vitamins or antibiotics on your own, since treatment should depend on the underlying cause.