A swollen armpit can be caused by a number of conditions, ranging from mild to serious. This is because the lymph nodes located under the arms can swell up due to infection, injury, or serious diseases. In fact, one of the most common causes of swelling under the arm is an infection, as many areas of the body drain into the lymph nodes in this area. Surface injuries or allergies to certain products, such as deodorant, can also result in swelling. While most causes are mild and treatable, cancer, including melanoma, lymphoma, and breast cancer, can also cause swelling in the lymph nodes.
Since the lymphatic system is supposed to remove bacteria from the body, swollen lymph nodes are often a sign that it is trying to fight off an infection. Infections that come from the hands, arms, and breasts are likely to affect the underarm since these areas drain into the lymph nodes located here. Other signs of infection include chills, a fever, and headache as the body attempts to fight it off.
Injuries on the surface of the skin can also result in swelling under the arm, especially if an infection results. Bites, scratches, and cuts may cause the lymph nodes to flare up, particularly when they are located in the underarm area, such as tiny cuts caused by shaving. Additionally, allergies to certain products, such as deodorant, perfume, soap, and shaving cream, may cause swollen lymph nodes, especially when they enter the body through cuts in the skin. Fortunately, the swelling should go down once the injury heals or the product is no longer used. If the swelling does not disappear on its own within days, the individual may need antibiotics.
Though most cases are quite treatable, armpit swelling can also be a symptom of various types of cancer. Since breast tissue includes the skin under the arm, swelling of this area may be a symptom of breast cancer, especially if it is painless and gradual. Lymphoma, which is cancer of the lymphatic system, can also cause the lymph nodes under the arm to swell, as can melanoma, or skin cancer. For this reason, this symptom should not be ignored. If the swelling does not decrease within a few days, an individual should see a medical professional to determine the underlying cause.