The armpit is one of the sensitive parts of the body. Numerous blood vessels and nerves run through the armpits. Besides, your armpits are close to the breasts, and you may think you have developed breast cancer.
Luckily, most pains in the left armpit are not life-threatening and do not require medical help. But there are also cases you feel a sharp and shooting pain in your armpit area, which may be a sign of a severe health condition.
Many causes can lead to pain in the left armpit. For example, Muscle strain, Lymphadenitis, Angina, Hidradenitis Suppurativa, Sporotrichosis, Cancer, heartburn, Shingles, Anxiety, Infection, Pleurisy, Injury, Pinched Nerve or Cyst, etc. Here are some of the common causes.
18 Common Causes of Pain in Left Armpit
1. Muscle Strain
The overuse or injury of chest or arm muscles may lead to pain in the armpit. The pectoralis is a large muscle of the chest that runs up to the shoulders. This muscle can be injured by lifting weights or sports. The coracobrachialis, a muscle in the upper arm, can be damaged or strained from throwing activities or sports, such as tennis, javelin, and baseball.
If the chest or upper arm muscles become inflamed or sprained, you may feel pain in the left armpit or both.
2. Lymphadenitis (Lymph nodes inflammation)
Lymph nodes are the oval-shaped organs that contain immune cells. These are responsible for attacking and killing unwanted contaminants or invaders, such as viruses. Lymph nodes are found in many parts of the body, such as the groin, neck, and armpits.
When you are sick or infected by a virus, the lymph nodes release disease-fighting cells and compounds. They may also become painful or inflamed. Inflamed lymph nodes are called lymphadenitis.
Your doctor may advise you to take a fever-reducing painkiller and warm compress. You can also alleviate the inflammation by elevating the affected area. Antibiotics can also help in fighting the infection that leads to inflammation.
If the lymph nodes are infected, an abscess may form. Your doctor will drain the abscess to alleviate the swelling. If the lymphadenitis is due to a cancerous tumor, the treatment may include surgery, radiation, and chemotherapy.
3. Pain in Left Armpit Caused by Angina
Angina is chest pain due to reduced blood flow to the heart muscles. The blood carries oxygen, which the heart needs to function correctly. When the heart is deprived of oxygenated blood, it also leads to a condition called ischemia.
Angina is a symptom of coronary artery disease and is commonly described as pressure, tightness, heaviness, or pain in the chest. Other symptoms of angina may include:
- Shortness of breath
- Dizziness, nausea
- Pain in arms, shoulder, neck, jaw, or back with chest pain
- Chest pain
People who smoke, with diabetes, high blood pressure, high blood cholesterol, lack of exercise, history of heart disease, and always stress have a higher risk of developing angina. If you are experiencing pain in the left armpit along with chest pain, seek medical help immediately.
4. Hidradenitis Suppurativa
Hidradenitis Suppurativa is a skin condition that comes with sore lumps. It usually develops where the skin rubs together, such as the groin, buttocks, armpits, and under the breast. The small lumps may break, smell, and create tunnels under the skin.
This condition may occur when the hair follicles are inflamed or blocked. Many factors can lead to blockages, such as hormones, genetics, metabolic syndrome, irregular immune system response, excess weight, and smoking.
The signs and symptoms may include:
- Red Bumps
- Pea-sized lumps
Early diagnosis and treatment can control the symptoms and avert further complications, such as infection, scars, limited movement, obstructed lymph drainage, social isolation, and cancer.
Sporotrichosis, or rose handler’s disease, is an infection caused by a fungus (Sporothrix Schenck). This fungus is related to mold or yeast. Sporotrichosis is commonly linked with scrapes or cuts that occur when handling vegetation (wood, moss, hay, sphagnum moss, sharp-stemmed plant, and soil). The infection is common among farmers, gardeners, and nursery workers. When the mold spores enter the skin, it may take days or months to develop.
The first symptom of this condition is a bump or nodule on the skin. The color may range from pink to purple. It is usually tender and mild but may develop an open sore (ulcer) that drains clear liquid. Without proper treatment, the nodule and ulcer can be severe.
It may also spread to the arms and legs and may last for years. In severe cases, the infection may spread to joints, bones, lungs, or the brain. If you think that you or someone you know might have Sporotrichosis, seek medical attention for proper diagnosis and treatment.
6. Breast Cancer
Breast cancer forms in the cells of the breast and may occur in both men and women. The cause of breast cancer is not apparent, but lifestyle, environmental factors, and hormones may increase the risk of breast cancer.
It often starts with cells in the milk-producing ducts or may begin in the breast’s glandular tissue or other tissue or cells. The signs and symptoms of breast cancer may include:
- Breast lump
- Change in shape, size, or appearance
- Skin changes or scaling, flaking, and peeling around the nipple
- Suddenly inverted nipple
- Redness or pitting the skin
To diagnose breast cancer, tests and procedures may include a breast exam, mammogram, breast ultrasound, biopsy, and breast MRI. If you are experiencing any of the signs and symptoms of breast cancer, see a doctor immediately for early treatment.
7. Heartburn or Acid Reflux
Another cause that can result in pain in the left armpit is heartburn. It is a burning sensation in the chest area behind the breastbone. The pain is usually worse when bending over or lying down. It occurs when the stomach acid backs up into the esophagus (a tube that transfers food from mouth to stomach). Heartburn that affects your daily tasks can sign a more severe condition that requires medical attention.
The symptoms of heartburn include:
- Pain that worsens when bending over or lying down.
- Chest pain that occurs after eating or at night.
If you are experiencing severe chest pain accompanied by other symptoms such as pain in the armpit, arm, jaw, or shortness of breath, seek medical help immediately.
8. Shingles near the Armpit
Singles are a viral infection that may occur in any part of the body. It looks like a single stripe of blisters that wrap around the right or left side of the torso. If there is an eruption near the armpit, it can cause armpit pain. Shingles are caused by the same virus (varicella-zoster virus) that causes chickenpox. The signs and symptoms of shingles may include:
- Pain, burning, numbness, or tingling sensation
- Red rashes
- Fluid-filled blisters that break open
A person with shingles may also experience a headache, fever, fatigue, and sensitivity to light. Seek immediate medical help if the rash or pain occurs near your eyes, if you are 70 or above, if you have a weak immune system due to illnesses, or if the rash is painful and already spreading.
Anxiety is also associated with underarm pain. It results in shaking, sweating, irritation, and rapid heart rate, which may cause pain in the underarms. People with anxiety disorders often have intense, persistent, and excessive worry about daily circumstances. These feelings and panic can affect your daily tasks. Other signs and symptoms of anxiety may include:
- Difficulty controlling worry
- Hyperventilation or rapid breathing
- Feeling tense or nervous
- Feeling tired or weak
- Difficulty sleeping
- Having the urge to avoid things that trigger anxiety
- Gastrointestinal problems
See a doctor if you think that you are worrying too much and it hinders your tasks, relationship, or other activities if you feel depressed and cannot control alcohol, drug intake, or suicidal thoughts.
10. Armpit Infection
Bacterial infections can result in fever, odor, and sore armpits. The condition could be caused by granular bacteriosis, trichomycosis axillaris, or folliculitis. If you find red splotches, lumps, and itchy spots, your pain in the left armpit could be caused by infected hair follicles or sweat glands. The most common causes of infection include:
- Poor hygiene
- Cosmetic products that contain harsh chemicals
- Extended periods of moist conditions underarms
- Excessive sweating or hyperhidrosis
The treatment of the infection depends on the underlying cause. If the condition occurred due to excessive sweating, your doctor might prescribe oral or topical drugs, antibiotics, and over-the-counter pain relievers.
It is important to use high-quality deodorants that do not contain harsh chemicals. Always keep your underarms dry and clean at all times to prevent sweat, oil, and bacteria from building up on your skin.
11. Breast Infection
Infections of the breast are commonly caused by Staphylococcus aureus, a type of bacteria found on the skin. Infection occurs when the bacteria penetrate through a crack or break in the skin, resulting in swelling.
This condition, which is also known as mastitis, occurs in breastfeeding women. A small percentage of infections not associated with breastfeeding is associated with rare forms of breast cancer.
Non-lactational mastitis may occur in women with a compromised immune system. Those who have diabetes or had lumpectomies may develop an infection. The common symptoms of breast infection may include:
- Abnormal swelling of a breast
- Presence of a painful lump in the affected breast
- Nipple discharge
- Burning sensation or pain during breastfeeding
- Enlarged lymph nodes in the neck or armpits region
Other symptoms may include warm breast, chills, redness, fever, breast tenderness, and nipple discharge. If you are experiencing pain in the left armpit along with some of the symptoms of a breast infection, contact your doctor for a proper diagnosis. During your treatment, you can also perform home remedies to relieve discomfort.
The lining of the lung and chest area may become inflamed. This may be caused by a wide variety of health conditions such as pneumonia, respiratory problems, and exposure to chemicals that may be toxic to the body.
The main reason why this condition is called pleurisy is that the lung and chest area is called “pleura.” Similar to Costochronditis, the pain brought about by this condition may be increased whenever there is any type of movement. For example, if you try to breathe deeply, this will make you feel a sharp pain in the left armpit.
13. Shoulder Dislocation
One of the possible causes of pain in the left armpit is the dislocated shoulder. A partial dislocation occurs when the humerus (top of the upper arm bone) is partially out of the glenoid (joint socket). When the humerus is all the way out of its socket, it is a complete dislocation. The symptoms of a dislocated shoulder include:
Dislocation of the bone may damage ligaments and nerves around the area. If you experience any of the symptoms mentioned, visit a specialist immediately. The doctor will place the humerus (upper arm bone) back into the glenoid (joint socket). He or she may also immobilize the shoulder for a few weeks.
You can also cool the area with ice three to four times daily to alleviate inflammation and pain. Once the swelling goes down, your doctor will prescribe rehabilitation exercises to strengthen the muscles and restore the range of motion.
14. Cerebrovascular Accident / Stroke
Cerebrovascular accident or stroke occurs when blood flow to a part of the brain is restricted by a blood vessel or blockage rupture. If you suspect that you or someone you know might have stroke symptoms, make sure that you visit a doctor quickly. Leaving it untreated for too long can cause permanent damages to the brain. The symptoms of a stroke are:
- Difficulty walking
- Dizziness, blurred vision
- Loss of coordination and balance
- Paralysis or numbness in the arm, leg, or face
- A sudden headache, usually accompanied by dizziness, nausea, and vomiting
- Difficulty speaking or understanding
If any of the symptoms are present, it is important to go to a fast prognosis and treatment hospital. Your doctor will perform tests to discover the cause and determine its location. Treatment will depend on the type of stroke.
To reduce your risk, limit cholesterol and saturated fat consumption. Maintain blood pressure, control diabetes, eat a diet rich in fruits and vegetables, and get regular exercise. Do not drink alcohol excessively and refrain from smoking.
15. Brachial Plexus Injury
Another possible cause of pain in the left armpit is brachial plexus injury. This condition occurs when the network of nerves that delivers signals from the spine to shoulders, arms, and hands are compressed, stretched, or torn. In minor cases, brachial plexus injuries are caused by contact sports, such as wrestling and football. However, tumors or inflammation may also lead to damages.
Severe brachial plexus injuries are caused by motorcycle or auto accidents and may leave the arm paralyzed. Surgical procedures will be required to restore sensation and function. Depending on the location and severity of the injury, the signs and symptoms of this condition are:
- Minor injuries – Burning sensation or electric shock shooting down the arm, weakness, and These symptoms may last for a few seconds to several minutes.
- Severe injuries – Symptoms include weakness, inability to use your shoulder, arm, or hand, and severe pain.
See a doctor if you experience weakness in your arm or hand, neck pain, and other symptoms of brachial plexus injuries. It is crucial to be treated immediately after the injury as it can result in permanent weakness or disability.
Overactive thyroid or hyperthyroidism is a condition in which the thyroid gland produces excessive hormone thyroxine. This boosts the body’s metabolism process significantly and leads to irregular heartbeat, sudden weight loss, irritability, nervousness, and sweating. In some cases, it may also cause pain in the left armpit. The common symptoms of hyperthyroidism include:
- Sudden weight loss
- Increased appetite
- Rapid or irregular heartbeat
- Trembling fingers
- Frequent bowel movements
- Brittle hair and thinning skin
- Anxiety, irritability, and nervousness
Other symptoms of hyperthyroidism include sweating, increased sensitivity to heat, changes in menstrual patterns, muscle weakness, and fatigue. Treatment depends on the physical condition, age, severity, and underlying cause. Your doctor may recommend anti-thyroid medications, radioactive iodine, beta-blockers, or surgery.
17. Pinched Nerve
The Pinch nerve could also be a cause of pain in the left armpit. It occurs when excessive pressure is applied to the affected nerve by surrounding tissues, such as muscles, bones, tendons, or cartilage. Other health conditions may lead to pinched nerve or nerves, such as obesity, sports activities, injury, repetitive work, wrist arthritis, or rheumatoid.
The signs and symptoms may include:
- Pins and needles or tingling sensations
- Reduced sensation or numbness in the area
- Burning, aching, or sharp pain
- Feeling that your hand does not function properly.
In most cases, conditions related to a pinched nerve are worse during the night. If you experience the signs and symptoms for a few days now, see a specialist immediately. The most recommended treatment for a pinched nerve is rest. Avoid any activities that can aggravate the condition. Your doctor may also recommend physical therapy and medications. Surgery may be required if the condition does not improve.
A cyst in your armpit may sound scary, but it does not pose a life-threatening condition. As a matter of fact, cysts can develop anywhere in the body. They are more likely to appear on the skin, and they are filled with pus, fluid, or air. Most cysts are usually harmless and caused by infections or blocked glands.
The common causes of armpit cyst are:
- Bacterial, fungal, or viral infection
- Fibrocystic breast changes
- Hidradenitis Suppurativa
In rare cases, a cyst in the armpit could be caused by cat scratch fever, mononucleosis, AIDS, and cancer. If the pain is not severe, you can try home remedies to eliminate the cyst. If the cyst and surrounding area are inflamed, visit a doctor to have it examined properly. Your doctor may recommend injecting steroids to alleviate the inflammation.
How to Treat Pain in Left Armpit
If the pain is mild or while you are waiting for your appointment, you can try simple remedies to reduce the pain.
- A cold compress or cold water can help you reduce itchiness and inflammation.
- Take a warm bath and add one tablespoon of baking soda to treat pain, itchiness, inflammation, and lumps.
- Practice good hygiene by washing your underarms daily with antibacterial soap and warm water.
- Massage the affected area gently to reduce swelling and improve blood circulation.
- Avoid spicy and oily foods as these can make you sweat. Eat more vegetables and fruits instead.