Your armpit, also known as the axilla, contains a large collection of lymph nodes, hair follicles, and sweat glands. A number of things can cause pain in the hollow created by your chest wall, muscles, and shoulder bones. A pulled muscle is one of the more benign causes.
A pulled muscle causing armpit pain may come from your pectoral muscles, triceps, or latissimus dorsi (lats). It also may come from the teres major muscles or the subscapularis, part of the rotator cuff.
Treatment for a muscle strain in your armpit depends on how severe your injury is.
What Happens During a Muscle Strain or Pull
Your muscles contain many individual fibers that can stretch only so far. A movement that stretches the muscle fibers past their natural range of motion can tear them.
Any movement that causes your pectoral muscles, triceps, or lats to become overstretched can cause an injury that leads to pain in your armpit. This injury can come from a single event, such as a fall, or from repeated extension or overuse.
The pain you feel may be mild, sharp, or severe. You may have even heard a popping sound or noticed bruising, swelling, or muscle weakness, the Cleveland Clinic says. A severe strain, or a complete tear, may result in loss of muscle function.
How to Gauge the Severity of a Strain or Pull
Muscle strains vary in severity, based on the symptoms. Knowing how severe your muscle strain is will help you figure out whether to treat the injury at home or visit your doctor.
According to Harvard Health Publishing, grades of muscle strains include:
- Grade I These are mild, involving only slight damage to the muscle fibers. The soreness may be uncomfortable, but it doesn’t prevent you from carrying out your daily activities. It may keep you from doing certain exercises, though.
- Grade II These are moderate injuries in which more muscle fibers are torn. The pain is likely more severe, and you may have swelling or bruising. You may also notice some muscle weakness when using your arm. Completing everyday activities could be harder to do, and exercise involving the upper body might be painful.
- Grade III In these severe strains, a muscle tears completely through or detaches from the tendon that connects it to bone. You may have heard a popping noise at the time of the injury, indicating this rupture. The pain, swelling, and bruising are severe, and there is a complete loss of muscle function. Daily activities and exercise are difficult or impossible.
How to Treat a Pulled Muscle
When you pull a muscle in or around your armpit, you need a treatment that’s appropriate for the severity of the strain. According to Cleveland Clinic, it’s best to call your doctor if you’re concerned about the pain, or if the pain happens along with symptoms such as tingling, a rash, or limited movement.
Grade I
If the muscle strain in your armpit is a grade I injury, you can treat it at home using the RICE method. Start it as soon as possible after your injury, and continue it for 48 to 72 hours.
According to Cleveland Clinic, RICE stands for:
- Rest Stop the activity that led to your injury, and avoid any activities that stress your sore underarm for at least 72 hours.
- Ice Apply an ice pack for 10 to 20 minutes each hour, as often as possible. Ice constricts the blood vessels to stop blood flow to the injured muscle, reducing swelling and bruising.
- Compression Wrap an elastic bandage snugly around your shoulder and through the armpit. Applying compression also helps reduce swelling and can provide support to a weakened muscle.
- Elevation Keeping the armpit at or above the level of your heart will help reduce blood flow to the injured area.
Be consistent with this treatment for the next two to three days. Doing so can reduce your pain, swelling, and recovery time.
Over-the-counter pain relievers also may help ease discomfort.
Grades II and III
If you have moderate to severe pain in your armpit, you should have a doctor check it out. To determine the scope of your injury, your doctor may:
- Ask how the strain happened.
- Ask if you heard a pop at the time of the injury.
- Examine the strained muscle.
- Ask you to perform physical tests, such as raising your arm, to determine muscle function.
- Order X-rays or magnetic resonance imaging (MRI) if a physical exam doesn’t provide enough information.
If your armpit muscle strain turns out to be a grade II injury, your doctor will likely send you home with instructions to carry out the RICE treatment. Use of an assistive device that keeps your arm from moving may protect it from further injury, and you may receive a prescription for a pain reliever.
Grade III injuries will require more comprehensive treatment, so your doctor will likely refer you to a specialist. Some complete muscle tears can be treated with immobilization via slings or casts. Others may require surgery.
How Long Recovery Takes
Your path to recovery will depend on which type of treatment you get.
Grade I strains may get better within a few weeks. Until that time, avoid strenuous activity involving your chest, lats, and arms on your injured side. Don’t pick up anything heavy or reach for something above your head. Avoid exercises that use those muscles.
For grade II and III strains, follow your doctor’s orders. Moderate strains can take two to three months to heal. Severe strains requiring surgery can take several months. During this time, you’ll need to limit your activities to those that your doctor and physical therapist say are safe.
Which Exercises Might Help With Armpit Pain?
At a certain point, all grades of muscle strain benefit from strengthening, flexibility, and mobility exercises. Depending on the muscle you strained, your pecs, lats, or triceps will likely lose some strength and range of motion while you’re recovering, even with a mild strain.
If you have a grade II or III strain, your doctor will tell you when you should start exercising. You may work with a physical therapist, who will design a program for you.
If your muscle strain was mild and you’re treating it at home, you can start to do some exercises once the pain and swelling are gone.
Do each of these exercises for three sets of 30 seconds, once or twice a day:
- Chest Doorway Stretch Stand in a doorway and raise your arm to shoulder height. Bend your elbow to 90 degrees and press your forearm against the door frame. Rotate your chest and hips away from your arm until you feel a stretch.
- Thoracic Extension Sit in a chair and bring both hands behind your head, elbows pointing out. Press gently against the back of your head while arching your spine and pushing your elbows out until you feel a stretch.
- Triceps Stretch Stand or sit upright. Raise your arm, bend your elbow, and place your palm against your middle upper back. Grasp your elbow with your opposite hand and push down gently.
- Arm Circles Reach your arms out to the sides and make small circular motions. Gradually widen the circles until you reach your full range of motion, then switch directions.
Do 10 repetitions of these exercises once or twice a day, holding each for five seconds each time:
- Isometric Chest Press your palms together at the center of your chest with your elbows at the same height as your hands. As you press, focus on the squeezing sensation in your chest.
- Scapular Retraction Stand with your arms at your sides. Roll your shoulders back and down, and squeeze your shoulder blades together.
Stop if you feel any sharp pain, and avoid overstretching the injured muscle.
When you return to your regular exercise activities, be conservative about increasing the intensity and load.
