Armpit lump

An armpit lump is a swelling or bump in the hollow under your arm. It may come from the skin, hair follicles, sweat glands, fatty or breast tissue, or lymph nodes.

Lymph nodes help the immune system respond to infection. Those in the armpit may swell because of infection or inflammation in the arm, chest, or nearby skin.

Many armpit lumps are temporary or treatable, but their cause cannot be confirmed by feel alone. Important clues include how long the lump has been present, whether it is changing, and whether you have other symptoms.

You may notice one lump or several. It might be:

• Tender, warm, or painless
• Soft and movable or firm and less mobile
• Close to the skin or deeper in the armpit
• Red, skin-coloured, or associated with a visible spot
• Stable, growing, or changing over several days

An infection may cause redness, warmth, pain, or pus. A swollen lymph node often feels like a small bean, while a cyst may feel smooth and rounded. These features do not confirm the cause.

Check for nearby cuts, bites, rashes, or infections. Also note breast or chest changes such as a new lump, skin dimpling, or nipple discharge.

Swollen lymph nodes may occur with a cold, sore throat, skin infection, or another infection. A node can also swell after a vaccine in the same arm and may take several weeks to settle.

Ingrown hairs and inflamed hair follicles can follow shaving, waxing, friction, or sweating. They often appear as tender red spots and may contain pus.

A skin abscess is a painful, warm pocket of pus. It may leak, but squeezing it can spread infection. Cysts may be painless unless inflamed or infected. A lipoma is a non-cancerous fatty lump that is usually soft, slow-growing, and movable.

Hidradenitis suppurativa causes repeated painful lumps, abscesses, drainage, and scarring, usually in the armpits or groin. Recurrent “boils” should be medically assessed.

Breast tissue can extend into the armpit and may become fuller or tender during hormonal changes.

Less commonly, a persistent lump may be related to lymphoma, breast cancer, skin cancer, or another cancer. Most armpit lumps are not cancer, but hard, fixed, enlarging, or unexplained lumps need assessment.

Arrange a same-day medical assessment if the lump rapidly becomes more painful, red, hot, or swollen, especially with fever or feeling very unwell. This may indicate an abscess or spreading skin infection.

Seek emergency help for severe breathing difficulty, confusion, collapse, or blue, grey, or unusually pale skin. These are signs of serious illness.

Book a routine appointment if:

• The lump remains after two to four weeks
• It is growing, hard, or difficult to move
• It keeps returning or repeatedly drains
• You have unexplained night sweats, weight loss, or ongoing fever
• You notice a breast or chest lump, skin dimpling, or nipple changes
• You have had cancer or have a weakened immune system

Do not delay assessment because the lump is painless. Pain does not reliably indicate whether a lump is serious.

A healthcare professional will ask when the lump appeared, how it has changed, and whether you recently had an infection, vaccination, skin injury, or new medicine. They may ask about fever, night sweats, weight changes, and breast or chest symptoms.

The examination may include both armpits and the skin of your arms, neck, chest, and breasts. You can ask what it involves and request a chaperone for a breast or chest examination.

An ultrasound may show whether the lump is a lymph node, cyst, abscess, or solid growth. Other tests may include blood tests, breast imaging, fluid sampling, or a biopsy, which removes a small tissue sample for examination.

Treatment depends on the cause. A lymph node reacting to a minor infection or vaccination may only need observation. Bacterial infections may require antibiotics like amoxicillin or doxycycline, while an abscess may need professional drainage. Antibiotics do not treat viral infections.

Until the cause is clear:

• Do not squeeze, pierce, or repeatedly press the lump
• Pause shaving or waxing if the skin is irritated
• Apply a warm, clean compress to a tender surface lump
• Keep draining skin clean and cover it with a dry dressing
• Use non-prescription pain relief only as directed on the label

Ask a pharmacist which pain relief is suitable for your health conditions and other medicines.

Hidradenitis suppurativa may require prescription skin treatments, tablets, injections, or surgery. A suspicious lymph node or breast-related lump may need specialist tests and treatment.

Lumps caused by minor infections, irritation, or vaccination often shrink over days to weeks. A lymph node may remain noticeable after you feel better.

Cysts and lipomas can persist even when harmless and may only need treatment if painful, infected, or troublesome.

Track the lump’s size and symptoms without repeatedly checking it. Arrange an appointment if it does not settle within two to four weeks or changes sooner. Attend any requested follow-up even if the lump remains painless.

Can deodorant cause an armpit lump?

Deodorant may irritate the skin or cause a rash, but it does not usually cause a deep lymph node lump. Stop using a product that causes burning, itching, or redness.

Can shaving cause one?

Yes. Shaving can irritate hair follicles or cause ingrown hairs. These lumps are often close to the skin, tender, or red.

Can a vaccine cause swollen armpit nodes?

Yes. A vaccine can temporarily enlarge lymph nodes on the same side as the injection. Tell a healthcare professional about recent vaccinations, particularly before breast imaging.

Does a painless lump mean cancer?

No. Painless lumps may be cysts, lipomas, or reactive lymph nodes. However, a persistent, enlarging, hard, or fixed lump should be examined.

Should I try to drain it?

No. Piercing or squeezing can worsen inflammation, spread infection, and make assessment harder. A lump containing pus may need safe drainage by a healthcare professional.