My armpit hurts but there is no lump

The armpit contains skin, hair follicles, nerves, blood vessels, muscles and lymph nodes. Tenderness may follow shaving, a new deodorant, a blocked follicle, a minor infection, lifting, exercise or an injury to the chest, shoulder or arm. Some lymph nodes can be tender before they are easy to feel. A breast lump is a possible presentation of breast cancer, but armpit pain alone does not establish that diagnosis. Lymphoma can affect lymph nodes, although a painful armpit without a lump has many non-cancer explanations.

Notice whether the pain is on one side, linked to arm movement, associated with a skin change, or accompanied by fever, breast changes or swelling elsewhere. These details help a clinician decide whether examination, imaging or another test is useful.

Avoid shaving or fragranced products over the sore area for a short period, and reduce activities that clearly trigger the pain. Gentle movement can help if the discomfort follows exertion; do not force a painful shoulder or arm. Check the skin and breast area in good light without repeatedly pressing the tissue. Record when the pain began, what changes it, and any medicines or recent vaccinations. Arrange a clinical appointment if it persists, returns, or interferes with sleep or movement.

Seek prompt medical care for a new or growing swelling, redness that spreads, warmth, fever, unexplained weight change, night sweats, nipple or breast changes, arm swelling, or pain that becomes severe. Seek urgent help for chest pressure, breathlessness, fainting, or sudden weakness. A clinician can examine the armpit, breast, shoulder and neck rather than judging the cause from pain alone.

Could the pain be coming from my skin, shoulder, breast or lymph nodes? What findings would make imaging useful? Which changes should prompt an earlier review?