Those who develop a cyst in the underarm often view it as a symptom of a very serious illness. While cysts can be indicative of serious health conditions, they most commonly are caused by a number of various infections with varying degrees of seriousness. The most common type of infection that can lead to cysts in the underarm are bacterial infections, though viral infections, such as the common cold, are also to blame. In some cases, cysts in the underarm may be caused by breast cancer. Those who have a family history of breast cancer should seek medical assistance immediately if they experience cysts in the underarm.

One of the most common causes of cysts in the underarm has been found to be bacterial infection. Typically, bacterial infections that lead to cysts in the underarm occur primarily due to antiperspirant use or shaving with a dirty razor. Those who develop a cyst in this location after switching to a new brand of antiperspirant or deodorant should consult with a dermatologist in order to make sure that this is, in fact, the cause of the cyst. In addition, those who notice an increase in the rate of occurence of cysts after shaving should consider switching to a new razor, or looking for a different brand of shaving cream. In some cases, a new shaving technique must be used in order to prevent infection.

In some cases, an infection that has been left untreated can lead to the development of an abscess. An untreated infection can cause the cyst to grow to a surprisingly large size, and can be very painful to the touch. While an abscess can often be treated through the use of prescription medications, in some cases, surgery or other more aggressive forms of treatment may be required.

A viral infection has also been commonly found to lead to the development of cysts in the underarm. Viral infections that can cause this condition typically include the common cold, influenza, or other similar respiratory conditions. Often, once the primary condition has been treated, the cysts in the underarm will also be eradicated.

One of the most serious causes of cysts in the underarm is breast cancer. Typically, these cysts grow relatively slowly, are small, and very hard. Those who have a family history of breast cancer and who develop cysts in the underarm should seek medical assistance as soon as possible. While not all tumors are cancerous, it is important to make a diagnosis as soon as possible for the best results.