Armpit discomfort without a lump: causes and next steps

Tender skin after shaving, a reaction to deodorant, an inflamed hair follicle, or friction can cause local soreness. Pain from the chest, shoulder or upper-arm muscles can also be felt in the armpit, especially after lifting or unfamiliar exercise. Some infections cause tenderness before swelling is obvious. Breast cancer and lymphoma can involve underarm lymph nodes, but discomfort alone cannot identify either condition.

Note when the discomfort began and whether arm movement, clothing, shaving or a skin product changes it. Examine the skin in good light for redness, a rash, a small spot or a cut, but avoid repeated pressing. Temporarily stop irritating products and strenuous upper-body activity. Arrange a routine appointment if the discomfort continues, returns, or has no clear trigger.

Seek prompt care for spreading redness, warmth, pus, fever, rapidly worsening pain, or swelling of the arm or breast. An appointment is also warranted for a newly felt node or lump, unexplained night sweats, persistent fever, unplanned weight loss, breast skin or nipple changes, or discomfort that does not settle. Urgency comes from these accompanying warning signs, not from guessing the cause.

Tell the clinician which side is affected, what movements trigger it, and whether you have noticed skin, breast or arm changes. Mention recent vaccination, infection, injury, shaving irritation, new products, breast surgery or cancer treatment. Ask whether the examination should include the breast, chest wall, shoulder and lymph-node areas.