Pain in Your Armpit? Cysts, Lymph Nodes, and When to See a Doctor

Pain in armpit areas is common and usually not serious. The armpit (also called the axilla) contains lymph nodes, sweat glands, hair follicles, nerves, muscles, and connective tissue. When something irritates or inflames any of these structures, discomfort can follow.

Most causes of pain in armpit regions are temporary and treatable. Still, some symptoms deserve medical attention. Here's what you need to know.

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Common Causes of Pain in Armpit Areas

1. Swollen Lymph Nodes

Lymph nodes are small, bean-shaped glands that help your body fight infection. You have several in each armpit.

When you're sick—especially with a cold, flu, skin infection, or even after a vaccine—lymph nodes can swell and become tender. This is called lymphadenopathy.

What it feels like:

• Tender or sore lump under the arm
• Swelling that may move slightly when touched
• Mild warmth or redness

Infections in the arm, breast, or chest can also cause swelling in nearby lymph nodes. In most cases, swollen nodes shrink back down within 1–3 weeks after the infection clears.

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2. Cysts

A cyst is a small sac filled with fluid, pus, or other material. In the armpit, cysts often form when:

• Hair follicles become blocked
• Sweat glands clog
• Skin trauma occurs (like shaving cuts)

What it feels like:

• A smooth, round lump
• Pain or tenderness if infected
• Possible redness or drainage

Infected cysts can turn into abscesses, which are more painful and may require medical treatment.

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3. Ingrown Hairs and Shaving Irritation

The skin in the armpit is sensitive. Shaving, waxing, or using deodorants can irritate hair follicles.

This may lead to:

• Small painful bumps
• Redness or itching
• Burning discomfort

Usually, this type of pain in armpit areas improves with gentle skin care and avoiding further irritation.

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4. Hidradenitis Suppurativa

This is a chronic skin condition that affects sweat glands. It can cause:

• Painful lumps under the skin
• Recurrent swelling
• Drainage or scarring over time

Hidradenitis suppurativa often starts after puberty and may require ongoing medical treatment. If you have repeated painful lumps in the same area, it's worth discussing with a doctor.

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5. Muscle Strain

Muscles in your chest and upper arm connect near the armpit. Heavy lifting, sports, or sudden movements can strain these muscles.

Signs of muscle-related pain:

• Pain that worsens with arm movement
• No visible lump
• Tenderness along the muscle

Rest and over-the-counter pain relief often help.

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6. Breast-Related Causes

Breast tissue extends into the armpit. Hormonal changes, infections (like mastitis), or other breast conditions can cause pain in armpit areas.

If you notice:

• A new breast lump
• Skin dimpling
• Nipple changes
• Persistent swelling

You should speak to a doctor promptly.

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7. Less Common but Serious Causes

Although rare, pain in armpit regions can sometimes be linked to more serious conditions such as:

• Certain cancers (including lymphoma or breast cancer)
• Severe infections
• Autoimmune diseases

These are not the most common reasons for armpit pain, but they should not be ignored if warning signs are present.

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When to See a Doctor

Most armpit pain resolves on its own. However, seek medical care if you notice:

• A lump that lasts more than 2–3 weeks
• A lump that grows larger
• Hard, fixed (non-movable) swelling
• Severe pain
• Fever or night sweats
• Unexplained weight loss
• Red streaking on the skin
• Drainage of pus
• Skin changes over a lump

If you have a history of cancer, any new swelling in the armpit should be evaluated.

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What You Can Do at Home

For mild pain in armpit areas without concerning symptoms, you can try:

• Warm compresses to reduce discomfort
• Resting the arm if muscle strain is suspected
• Gentle skin care (avoid harsh deodorants or shaving temporarily)
• Over-the-counter pain relievers like acetaminophen or ibuprofen (if safe for you)
• Good hygiene to prevent infection

Avoid squeezing lumps. This can worsen inflammation or spread infection.

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How Doctors Diagnose Armpit Pain

If you see a healthcare provider, they may:

• Ask about recent illness or injury
• Perform a physical exam
• Order imaging (such as ultrasound or mammogram)
• Recommend blood tests
• In rare cases, perform a biopsy

Most evaluations are straightforward and focused on ruling out serious causes.

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Is It a Lymph Node or Something Else?

It can be hard to tell what's causing pain in armpit areas on your own. Lymph nodes typically:

• Feel soft or rubbery
• Are tender during infection
• Move slightly under the skin

Cysts often:

• Feel smoother
• Sit closer to the skin surface
• May show redness

If you're unsure whether swelling is related to lymph nodes, you might find it helpful to use a free symptom checker for a lump in the neck to better understand what could be causing your symptoms. Since swollen lymph nodes in the neck and armpit often share similar underlying causes, checking your symptoms can help you determine whether you should seek medical attention.

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Special Considerations

After Vaccination

Some vaccines, including certain COVID-19 vaccines, can temporarily cause swollen lymph nodes in the armpit. This usually resolves within a few weeks.

During Pregnancy or Breastfeeding

Hormonal changes and breast infections can cause pain in armpit regions. Mastitis requires prompt treatment to prevent complications.

In Children

Swollen lymph nodes are very common in children and often linked to minor infections. Still, persistent swelling should be checked.

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When It's an Emergency

Seek immediate medical care if you experience:

• Rapid swelling
• High fever
• Difficulty breathing
• Severe spreading redness
• Signs of a serious allergic reaction

These situations are uncommon but require urgent attention.

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The Bottom Line

Pain in armpit areas is usually caused by:

• Swollen lymph nodes
• Cysts or blocked glands
• Skin irritation
• Muscle strain

Most cases improve with simple care. However, persistent lumps, worsening pain, or concerning symptoms should not be ignored.

Trust your instincts. If something doesn't feel right—or if symptoms last longer than expected—it's important to speak to a doctor. Early evaluation can provide reassurance and, when necessary, ensure timely treatment of potentially serious conditions.

Your body often gives clear signals when it needs attention. Listening to those signals—and acting when appropriate—is the healthiest approach.