You feel it when you reach overhead. You feel it when you try to sleep on your side. And oddly enough, that dull ache has worked its way into your armpit. So now you’re wondering — can a torn rotator cuff cause pain in the armpit?
It’s a surprisingly common question we hear at Pyramid PT in San Antonio, and it’s not without good reason. Shoulder pain that extends into the armpit can be unsettling, especially when you’re unsure what’s causing it. Whether you’re dealing with an old injury, persistent soreness, or a sudden sharp pain that caught you off guard, understanding what’s behind it is the first step toward relief.
Let’s break it all down.
Understanding the Shoulder Anatomy and the Rotator Cuff’s Role
The shoulder isn’t just one joint — it’s a finely-tuned network of bones, muscles, tendons, and nerves working together to give you an incredible range of motion. At the center of it all is your rotator cuff, a group of four muscles and their tendons that stabilize the shoulder joint and help you lift and rotate your arm.
Now, here’s where it gets interesting: your armpit region, or axilla, isn’t technically part of the shoulder joint — but it is closely connected through nerves and muscles. So when there’s a problem like a rotator cuff tear, the pain can refer or radiate to nearby areas, including the armpit.
And yes — that means a torn rotator cuff can absolutely cause pain that shows up in your armpit.
Common Causes of Armpit Pain Related to Shoulder Issues
So what might be behind the pain? Here’s a closer look at how shoulder and armpit pain often tie together:
1. Rotator Cuff Tear (Partial or Full Thickness)
When one or more of the rotator cuff tendons tear, either from overuse or injury, you may feel pain not just in the top or back of the shoulder — but deeper in the armpit. Why? Because the surrounding muscles and nerves in that region get irritated or overworked trying to compensate.
2. Shoulder Impingement Syndrome
This happens when the tendons of the rotator cuff get pinched during arm movement, especially overhead. The pain often radiates into the side of the arm and armpit, and may feel worse when you lie on that side.
3. Biceps Tendon Involvement
The long head of the biceps tendon runs right near the rotator cuff and dives into the front of the shoulder — very close to the armpit. If the tendon becomes inflamed or damaged, it can mimic or add to rotator cuff symptoms and contribute to pain in the upper inner arm and armpit area.
4. Referred Pain from Nerve Irritation
Nerves like the brachial plexus pass through the shoulder and into the arm. If they’re compressed or irritated due to a rotator cuff injury, that discomfort might travel down toward the armpit or even the chest wall.
5. Postural Compensation
Pain leads to compensation. If you’ve been guarding your shoulder, your posture changes, and the muscles under your shoulder blade and near the armpit start to overwork. The result? Deep soreness or a pulling pain in the axillary region.
Diagnosing the Root of the Problem
Knowing whether your armpit pain is truly linked to a torn rotator cuff — or something else — takes a little investigation. Here’s what we at Pyramid PT look for:
Self-Assessment Red Flags
If you notice any of the following, it’s worth getting evaluated:
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Pain when lifting or rotating your arm
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Weakness or difficulty raising your arm above shoulder height
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Pain that worsens at night or when lying on one side
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A dull ache that spreads from the shoulder into the armpit or upper arm
Clinical Evaluation
A physical therapist or orthopedic provider will run through range-of-motion tests, strength evaluations, and palpation of the shoulder and axilla to pinpoint what’s really going on. In some cases, imaging like MRI or ultrasound can confirm a tear or inflammation.
Rule Out Other Conditions
Pain in the armpit can also be linked to lymph node swelling, brachial plexus injuries, or even referred cardiac or lung pain in rare cases. This is why getting a proper diagnosis is crucial — and not something to delay.
Treatment Options for a Torn Rotator Cuff (and That Armpit Pain)
The good news? You don’t always need surgery to fix it — especially if you catch it early. Here’s how we treat it at Pyramid PT in San Antonio:
Home Strategies
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Rest (but not too much): Avoid overhead lifting or aggravating movements, but stay gently mobile.
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Ice & Heat Therapy: Ice can reduce inflammation, and heat can loosen up stiff muscles.
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Postural Correction: Better shoulder posture can reduce strain on both the rotator cuff and armpit muscles.
Physical Therapy (Your Best First Step)
This is where real recovery happens. A targeted PT program can:
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Strengthen the rotator cuff and supporting muscles
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Improve joint mobility and range of motion
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Reduce nerve tension and inflammation
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Address posture and movement patterns to prevent recurrence
You’ll work on restoring function, not just masking the pain.
Medical Intervention (If Needed)
If conservative care doesn’t relieve your symptoms, you might need:
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Corticosteroid injections
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Platelet-rich plasma (PRP) treatments
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Surgical repair (for full-thickness tears or chronic damage)
But again — many rotator cuff-related armpit pain cases respond extremely well to physical therapy when started early.
How to Prevent Future Shoulder and Armpit Pain
Once you’ve dealt with rotator cuff trouble, prevention becomes your long-term game. Here’s what we recommend:
Stay Strong and Mobile
Focus on strengthening your rotator cuff, scapular stabilizers, and core. We also teach mobility exercises for the shoulder joint to keep everything moving freely.
Fix Your Posture
Rounded shoulders and forward head posture? They’re major culprits. Good posture sets the foundation for shoulder health.
Smart Movement Patterns
If you’re a weightlifter, swimmer, or work overhead — we’ll coach you on better technique to reduce strain.
Regular Tune-Ups
Physical therapy isn’t just for pain. Checking in for movement assessments and mobility training can help you avoid bigger issues down the road.
Let’s Get Real — If Your Shoulder Hurts and It’s Spreading to Your Armpit, Let’s Talk
Armpit pain tied to a torn rotator cuff isn’t something you want to ignore. It’s a warning sign — not just of injury, but of imbalance, overuse, or nerve irritation that’s only going to snowball if left untreated.
At Pyramid PT in San Antonio, we specialize in solving problems like these with a hands-on, movement-focused approach. No cookie-cutter protocols. No endless waiting rooms. Just real answers, real relief, and a path back to strong, pain-free movement.
Schedule your one-on-one shoulder assessment with Pyramid PT today, and let’s figure out exactly what’s going on — and how to fix it.