Armpit pain is not uncommon, and it has many causes. The armpit or axilla contains lots of nerves, tendons, ligaments, and lymph nodes. Damage or inflammation to any of these components can lead to pain. Some armpit pain is caused by temporary injury or irritation, but sometimes armpit pain signals something more serious.
Skin irritation is one cause of armpit pain, and it can be caused by infections, medications, and allergies. Some of the most common allergens that affect the armpit are soap, deodorant, shaving cream, and fabric softener. People who suspect an allergy is causing a rash or irritation in the armpit should avoid the suspected allergen to prevent future problems.
Muscle Strain or Injury
Muscle strain can also cause armpit pain. Muscle strain can be minor from overuse or significant when the muscle is partially or completely torn. Although muscle strain or injury is more common in the back and lower limbs, it does happen to the muscles in and around the shoulder, as in a rotator cuff injury, leading to pain in the armpit.
Swollen Lymph Nodes
Another cause of armpit pain is a swollen lymph node, which indicates that something is causing a response from the immune system. They may or may not be tender. A swollen lymph node can be as big as a pea, golf ball, or larger, depending on the cause. In most cases, swollen lymph nodes are a normal reaction to an infection, though when found under the armpit, there is a possibility they are a sign of breast cancer and should be checked by a doctor.
The same virus that causes chickenpox causes shingles. Anyone who has had chickenpox can develop shingles. Before the rash appears, people experience pain and tingling. Shingles usually appear in a single line down the side of the body, following the nerve roots. If it appears near the armpit, it can cause armpit pain.
Peripheral Artery Disease
Peripheral artery disease (PAD) affects the arteries that carry blood to the limbs. It most commonly affects the legs, but it can happen in the arms, too. PAD causes narrowing or blocking of the arteries, which prevents blood from passing through. Eventually, this leads to tissue damage and tissue death. Pain in the legs is a common symptom of PAD, but it can occur in the arms and armpit if the disease is in the upper limbs.
A yeast infection is different from irritation or an allergic rash. Yeast normally lives on the skin, but it can overgrow in the right conditions, particularly in areas of the body that are warm and moist, like the armpit. Yeast infections leave the skin very red, and it may itch or burn. Most are easily treatable with ointment or antifungal pills.
Another cause of armpit pain is Hidradenitis suppurativa, a rare, chronic condition that causes boils to form under the skin. It most often appears in areas of the body where the skin rubs together, like under the armpit. Typically, the boils swell, drain, and heal, leaving thick scars that can cause pain and restrict mobility.
Diabetic Nerve Damage
Nerve damage from diabetes can also cause armpit pain. This type of neuropathy typically begins in the lower extremities and progresses to include the arms and hands. In addition to cramps and sharp pains, diabetic neuropathy can also cause. tingling, burning, or numbers. People with this condition are also are at risk for foot ulcers and infections.
Angina is chest pain, but it can radiate to the arm and cause armpit pain. It is a symptom of coronary artery disease and presents as a heaviness or tightness in the chest. In addition to radiating to the arm, angina can also cause pain in the neck, jaw, back, and shoulders. The most common type of angina is stable angina, which occurs when people exert themselves. Unstable angina can lead to a heart attack, so any chest pain should be considered a medical emergency.
When to See a Doctor
Many things cause armpit pain, some more serious than others. Anyone who experiences armpit pain accompanied by dizziness, shortness of breath, or pain in the chest, shoulder, or jaw should see a doctor immediately. Other causes of armpit pain, like a rash, pulled muscle, or swollen lymph node, indicate a possible need to check with a doctor for diagnosis and treatment.