01 · Overview
The short version
The same pain can start in different places
Pain under the arm may come from skin, lymph nodes, muscles, tendons, nerves, the shoulder, or nearby chest tissue. Location alone does not identify the cause.
Movement clues matter
If the pain changes when you lift, push, pull, or reach, an arm or shoulder strain becomes more likely. If it hurts more when the skin is touched, a skin problem is more likely.
Lumps need context
A tender lump can be a reactive lymph node or a skin infection. A painless, persistent, hard, or growing lump needs medical review sooner.
Whole-body symptoms raise concern
Fever, weight loss, night sweats, chest pain, shortness of breath, or ongoing fatigue can point to a broader illness, not just a local sore spot.
02 · Care guidance
When to get help
Emergency help
- Call 911 right away if armpit pain comes with chest pressure, shortness of breath, fainting, severe swelling of the face or throat, or sudden weakness, because those can be signs of a medical emergency.
- Get urgent help for stroke symptoms or signs of a severe illness if they are part of the overall illness picture; do not wait to see if armpit pain improves.
Get advice promptly
- Contact a clinician soon if the pain lasts more than a few days, keeps coming back, follows an injury, or comes with a new lump, redness, warmth, drainage, fever, unexplained weight loss, or night sweats. Seek prompt care if the pain is paired with a breast change, arm weakness, numbness, or pain that makes it hard to move the shoulder.
If the pain is mild, clearly linked to a minor strain or skin irritation, and you otherwise feel well, arrange a non-urgent visit if it does not improve over 1 to 2 weeks or if it keeps recurring.
03 · Armpit Pain
What the pain pattern can tell you
The way the pain behaves often gives more useful clues than the spot where you feel it.
Armpit pain is not one diagnosis. It can feel sharp, dull, sore, burning, or tender to the touch, and each pattern points in a different direction. Pain that shows up only with movement often points toward muscle, tendon, or shoulder trouble. Pain that feels like a sore spot in the skin raises the chance of irritation, a boil, or another surface problem.
It also helps to notice whether the pain is constant or comes and goes. Pain that keeps returning after the same activity suggests a repeat trigger. Pain that starts with a new lump, redness, or drainage suggests a problem in the skin or lymph nodes rather than simple overuse.
A short note about when it started, what makes it worse, and whether anything else changed nearby can make a later exam more useful.
- Sharp, burning, or sore can each suggest different sources.
- Movement-related pain often points away from the skin alone.
- A new lump, rash, or drainage changes the concern level.
04 · Armpit Pain
When the problem starts in the arm or shoulder
A pulled muscle, irritated tendon, or other arm injury can be felt under the arm even when the armpit itself is not the main problem.
MedlinePlus notes that arm injuries and disorders can involve tendinitis, bursitis, sprains, dislocations, fractures, and nerve problems. Because the armpit is close to the shoulder and upper arm, pain from those problems can be felt there, especially after sports, a fall, an accident, or repeated reaching.
This kind of pain often gets worse when you raise the arm, push, pull, or lie on that side. You may also notice stiffness, bruising, a weak feeling, or reduced motion. Those clues matter because a strain is handled differently from a joint injury or a broken bone.
If the pain followed a clear injury, or if the arm looks deformed or motion is much more limited, that needs earlier evaluation.
- Lifting, throwing, or repetitive reaching can irritate nearby muscles and tendons.
- Pain tied to motion is a common clue for shoulder or upper-arm involvement.
- A fall, deformity, or major loss of motion should not be watched for long.
05 · Armpit Pain
Skin irritation, boils, and sweat gland problems
The armpit skin is sensitive, so a small surface problem can cause real pain.
Shaving, friction, sweating, and irritated skin can make the armpit burn or sting. Sometimes the soreness is easy to point to with one finger. A small inflamed hair follicle, an ingrown hair, or a skin infection can feel much worse than it looks early on.
A painful bump, warmth, redness, or drainage suggests inflammation or infection rather than simple dryness. Repeated painful lumps in the same spot deserve more attention because recurring skin inflammation can leave scars and may need treatment.
Keeping the area clean and dry can reduce irritation, but skin pain that keeps returning should not be written off as just a product reaction if there is a lump or drainage.
- Shaving or friction can make a sore spot worse.
- Warmth, spreading redness, or pus points to possible infection.
- Repeated painful lumps should be checked.
06 · Armpit Pain
Swollen lymph nodes and body-wide illness
A lump in the armpit may be a lymph node reacting to infection or inflammation, but persistent painless swelling needs more attention.
Lymph nodes sit in the armpit and can enlarge when the immune system is reacting to something nearby or farther away. A swollen node may feel like a pea, bean, or larger lump and may be tender if it is reacting to inflammation.
MedlinePlus says non-Hodgkin lymphoma can cause swollen, painless lymph nodes in the armpits, along with unexplained weight loss, fever, soaking night sweats, coughing, trouble breathing, or chest pain. Sarcoidosis can also involve swollen lymph nodes, including in the armpits, and may come with fatigue, fever, night sweats, cough, shortness of breath, joint pain, or skin changes.
That does not mean a lump is cancer or sarcoidosis. It means a lump that does not go away, grows, or comes with body-wide symptoms should be examined.
- Tender, short-lived swelling is often reactive.
- Painless persistent swelling is more concerning.
- Weight loss, fever, and night sweats make evaluation more important.
07 · Armpit Pain
Which symptoms should move you to faster care
Armpit pain is more urgent when it is not alone.
Seek prompt care if the area becomes very red, hot, swollen, or drains fluid, because that may mean infection. A lump that is hard, fixed, or rapidly enlarging also deserves quick attention. A change in the breast, such as a new lump, skin dimpling, nipple discharge, or a change in shape, should be reported even if the armpit is the part that hurts most.
Whole-body symptoms matter too. Fever, unexplained weight loss, soaking night sweats, cough, shortness of breath, chest pain, weakness, or ongoing fatigue can point to an illness beyond the armpit itself.
If the pain is severe enough to limit movement, or if it came after injury, that is another reason not to wait.
- Rapidly spreading redness or swelling can be infection.
- A hard, fixed, or growing lump should not be watched indefinitely.
- Breast changes and body-wide symptoms deserve a closer look.
08 · Armpit Pain
What an appointment usually involves
The exam is meant to sort out whether the pain is coming from the skin, a lymph node, the shoulder, or another nearby structure.
A clinician will usually ask when the pain started, what makes it better or worse, whether you noticed a lump, and whether you had a recent injury, illness, or other new symptom. They may examine the armpit, shoulder, arm, and breast area, and check whether movement changes the pain.
If a lymph node or other lump needs more attention, testing may include blood work, imaging, or a biopsy. MedlinePlus notes that lymphoma diagnosis may use a physical exam, blood tests, a chest x-ray, and a biopsy. Sarcoidosis may also be checked with blood tests, imaging, and sometimes biopsy, depending on where the symptoms are.
- Bring a timeline of symptoms and any lump changes.
- Mention fever, night sweats, weight loss, cough, or breast changes.
- Testing depends on what the exam shows.
09 · Armpit Pain
What to do while you wait for care
Simple steps can reduce irritation, but they should not delay care when warning signs are present.
If the pain seems mild and local, rest the area and avoid the activity that seems to trigger it. Gentle movement can help keep the shoulder from stiffening, as long as movement does not make the pain much worse. If shaving, friction, or a product seems to irritate the skin, pause that trigger for now.
Do not squeeze a lump or try to drain it yourself. Track whether the lump changes, whether the skin gets red or warm, and whether you develop fever, cough, night sweats, or weight loss. Those details help a clinician decide what kind of problem this is and how quickly it needs to be handled.
- Rest the trigger, but do not force complete immobility unless told to.
- Do not squeeze or pick at a lump.
- Write down new symptoms, because they change the urgency.
10 · FAQ
Questions people ask
Is armpit pain usually from the armpit itself?
Not always. The skin, lymph nodes, muscles, tendons, shoulder, chest wall, and nearby breast tissue can all send pain to that area. The pattern of pain and any lump, rash, or movement trigger usually gives more clues than the location alone.
Can exercise cause armpit pain?
Yes. A strain, tendon irritation, or sore chest and shoulder muscle can feel like armpit pain, especially after lifting, pushing, or new upper-body workouts. Pain that improves with rest and returns with the same activity is more suggestive of a muscle-related cause.
Could swollen lymph nodes cause pain under the arm?
Yes. Lymph nodes may become tender when they react to infection or inflammation. A painless lump, especially if it lasts, grows, or comes with fever, night sweats, or weight loss, should be checked sooner.
What does a painful armpit lump mean?
A painful lump is often related to a swollen lymph node, irritated skin, or a small infection, but it is not possible to tell from feeling alone. A hard, fixed, or growing lump, or one with fever or weight loss, needs medical review.
Could armpit pain be from a more serious illness?
Sometimes. Less common causes include conditions that affect lymph nodes or the immune system, such as lymphoma or sarcoidosis. These are more concerning when pain is paired with painless swelling, fever, night sweats, weight loss, cough, or breathing changes.
Should I worry if the pain is only on one side?
One-sided pain often comes from a local problem such as a muscle strain, skin irritation, or a single swollen lymph node. That said, one-sided pain with a new breast change, a growing lump, or trouble moving the shoulder should be checked rather than ignored.
What should I tell the clinician about my symptoms?
Say when the pain started, what makes it worse, whether there is a lump, and whether you have fever, weight loss, night sweats, cough, or shortness of breath. Mention any recent injury and any change in the breast, shoulder, or arm, because those details help narrow the cause.
11 · References
References and supporting evidence
These sources support the points identified below. Source checking is not clinical approval.
- S1: Arm Injuries and DisordersMedlinePlus / U.S. National Library of Medicine
Explains that arm and shoulder injuries can involve tendons, joints, bones, and nerves, which can make pain felt near the armpit.
- S2: LymphomaMedlinePlus / U.S. National Library of Medicine
Explains that persistent armpit lymph node swelling can be a lymphoma symptom and lists body-wide warning signs that make evaluation more important.
- S3: SarcoidosisMedlinePlus / U.S. National Library of Medicine
Explains that sarcoidosis can involve the lymph system and other organs, which helps frame armpit lymph node swelling with broader symptoms.
General information, not a diagnosis. This guide is not a substitute for care from a qualified healthcare professional. For an emergency, call 911 in the US or your local emergency number. Illustrations are conceptual and are not diagnostic images.