What’s Behind The Swollen Lymph Nodes in Armpits

Finding a tender lump in armpits (also known as your lymph nodes) can feel alarming, but they’re often your body’s way of signaling that something is going on — and that your immune system is doing its job. Lymph nodes are small, bean-shaped glands that help filter out harmful substances. When they swell, it usually means your body is fighting off infection, inflammation, or another condition.

These nodes are found in many places — the neck, armpits, abdomen, groin, and chest — but swelling in the armpit may indicate an issue related to the arm, chest, or breast.

Common Causes of Lymph Node Swelling Under Arms

• Viral Infections
  • Colds, the flu, or other upper respiratory infections can trigger swelling in the armpit nodes. This is your body’s immune system ramping up its defenses.
• Skin Infections
  • Infected cuts, boils, or conditions like cellulitis in the arm or chest can cause nearby lymph nodes to swell.
• Breast Infections and Conditions
  • Issues such as mastitis or other breast-related conditions can cause the lymph nodes under the arm to enlarge, since these nodes help drain the breast area.
• Injury or Inflammation
  • An injury to your arm or shoulder, or systemic conditions like arthritis, may prompt swelling as part of the healing or inflammatory response.
• Allergies
  • Some allergic reactions or medications may lead to mild lymph node enlargement.
• Lyme Disease
  • Transmitted through tick bites, Lyme disease can cause swollen lymph nodes along with fever, fatigue, and joint pain.
• Autoimmune Disorders
  • Conditions like rheumatoid arthritis and lupus involve widespread inflammation, which can trigger lymph node swelling in multiple areas.
• Cancer
  • Although less common, swelling can sometimes be a sign of lymphoma, leukemia, or breast cancer. Cancerous cells can travel through the lymph system and accumulate in lymph nodes.

What do swollen lymph nodes in the armpit feel like?

Swollen lymph nodes under the arm may feel like:

• Small, firm bumps — Usually about the size of a pea or marble
• Tender to the touch — Especially early on or during an active infection
• Hard or immobile — Sometimes a sign of a more serious underlying issue

They may look like slightly raised or reddened areas under the skin, or go unnoticed unless touched. Any swelling that lasts more than two weeks, continues to grow, or is accompanied by fever or fatigue should be evaluated by a provider.

When should you see a health care provider?

Reach out to your doctor if the lymph node swelling is:

• Persistent (lasting more than two weeks)
• Painful or growing
• Paired with systemic symptoms like fever, weight loss or night sweats

Your primary care provider can typically start the evaluation. Depending on findings, they may refer you to:

• Internal medicine specialists
• Infectious disease doctors
• Oncologists (if cancer is suspected)

How to relieve swollen lymph nodes under the arm

While medical evaluation is important, especially for persistent swelling, you may find some relief from the following supportive measures:

• Rest — Give your body time to heal by avoiding strain on the affected side.
• Ice or warm compresses — Ice can help reduce swelling, while warmth improves circulation and comfort.
• Hydration and nutrition — Drink plenty of water and eat a balanced diet to support immune function.
• Over-the-counter medication — Ibuprofen or acetaminophen can help manage pain or inflammation.
• Gentle hygiene — Clean the area with mild soap and avoid irritating products or tight clothing.

Physical Therapy Can Help Pain & Discomfort from Swollen Lymph Nodes in Armpits

While physical therapy doesn’t treat the root cause of swollen lymph nodes, it can support the body’s natural healing process, especially if the swelling limits range of motion or causes discomfort.

Soft Tissue Techniques

Gentle manual therapy can help improve circulation and lymphatic drainage, easing pressure around the swollen node.

Myofascial Release

This hands-on technique targets the fascia — the connective tissue surrounding muscles — to reduce tension and promote lymphatic flow.

Manual Lymphatic Drainage

A specialized form of massage, this technique uses light, rhythmic strokes to encourage the movement of lymph fluid through the body and reduce swelling.

Stretching & Gentle Exercises

Once cleared by your provider, your PT may guide you through movements that restore range of motion and relieve tightness around the armpit and shoulder.

Lattimore Physical Therapy Can Help You Feel Your Best!

Whether your lymph node swelling is from an injury, infection, or chronic condition, our team is here to support your recovery. At Lattimore Physical Therapy, we create personalized care plans using gentle, effective techniques designed to relieve discomfort and restore function.

Schedule your appointment today to learn more about how we can help you feel better, faster.