What are common reasons for experiencing underarm pain?

There are several common reasons why you might feel pain under your arm. One common cause is muscle or soft tissue strain. This can happen if you overuse your arm or do too many heavy lifts. Nerve irritation is another possibility, where a nerve in your shoulder or upper chest becomes pinched or pressed, sending sharp or dull signals to your underarm. Swollen lymph nodes, which help fight infections, might also cause pain if you have an infection nearby. Sometimes, after surgeries like breast removal or other procedures in the armpit, a condition called axillary web syndrome can occur. This makes the tissue feel tight and sometimes painful when you move. Even daily movements or exercise that put extra pressure on this area can cause discomfort. All these causes mean that underarm pain is usually linked to how your muscles, nerves, or lymph nodes are doing. If the pain keeps coming or gets worse, you can check your symptoms with our free AI symptom checker to better understand what might be causing your discomfort and whether you should talk with a healthcare provider to make sure you get the right care.