Pain in the armpit, or axilla, is a common complaint arising from the complex structures within this region. The armpit is a crowded space containing skin, muscle, nerves, blood vessels, and lymph nodes. The source of discomfort can range from minor surface irritation to deeper muscular issues or internal inflammation. While most instances of armpit pain are temporary, persistent or severe pain warrants a consultation with a healthcare professional.
Causes Related to Skin and Sweat Glands
Superficial Irritations
The armpit skin is prone to irritation due to high concentrations of hair follicles and sweat glands, combined with warmth and moisture. A painful lump can be an ingrown hair or folliculitis, an infection of the hair follicle often caused by Staphylococcus aureus. These conditions present as small, red, tender, pimple-like bumps, frequently occurring after hair removal. Contact dermatitis is another superficial cause, resulting from an allergic reaction to products like deodorants or soaps. This irritation leads to a painful, itchy rash that resolves when the offending product is removed.
Chronic Skin Conditions
A more chronic and severe condition is hidradenitis suppurativa (HS), which involves the blockage and inflammation of hair follicles and sweat glands. HS is characterized by deep, painful, pea-sized lumps that may enlarge, rupture, and leak pus. These lumps sometimes form tunnels under the skin.
Swollen Lymph Nodes
Swelling of the axillary lymph nodes, known as lymphadenopathy, is a frequent cause of armpit pain. These bean-shaped organs filter fluid draining from the arm, breast, and chest wall, making them central to the immune system. When the body fights an infection, white blood cells multiply within the nodes, causing enlargement and tenderness. Localized infections, such as a skin infection or a common cold, are the most common reasons for this temporary swelling. The nodes typically feel movable, soft, and painful when pressed, subsiding once the underlying illness resolves. Systemic illnesses like mononucleosis or influenza can also cause widespread lymph node swelling, including in the armpit. Swollen nodes that are hard, fixed, non-tender, or persist for more than a few weeks require medical evaluation.
Muscular Strain and Nerve Irritation
Muscular Strain
Pain deep within the armpit aggravated by movement often points to a structural origin. A pectoral muscle strain is a common culprit, especially after intense physical activity like weightlifting or throwing. This strain involves the large chest muscles that connect near the armpit. The pain radiates into the axilla and worsens when the muscle is stretched or contracted forcefully.
Nerve Irritation
Nerve irritation can cause sharp or burning pain in the area. Intercostal neuralgia involves the compression or inflammation of nerves that run between the ribs, sending shooting pain into the armpit. Following surgeries like a mastectomy, nerves in the area can become damaged, leading to chronic or phantom pain. This discomfort is often described as a burning, tingling, or numb sensation, distinct from a muscle ache.
When Pain Requires Immediate Medical Attention
Focusing on the left armpit, certain accompanying symptoms require immediate emergency evaluation. The most concerning is referred cardiac pain, where heart discomfort is perceived in the left armpit, shoulder, or jaw. If this pain is accompanied by chest tightness, shortness of breath, sweating, or dizziness, it could signal a heart attack or angina. Other serious issues include signs of a rapidly progressing infection, such as high fever, red streaking, or an inability to move the arm due to severe pain. Any new, hard, or fixed lump that does not resolve within two weeks, or changes in breast tissue, also necessitates prompt medical assessment.