Symptoms · Armpit
A lump or swelling in the armpit
The short answer
Most armpit lumps are swollen lymph nodes reacting to an infection or injury in the arm, hand or breast, and they settle in a few weeks. Painful lumps that keep coming back, with pus, in the armpit and groin may be hidradenitis suppurativa. A lump that is hard, painless, growing, or lasting more than three weeks, or that comes with a change in the breast, needs a doctor's check. Go to the emergency room for a hot, red, very painful swelling with fever.
How patients describe it
- A lump under my arm
- A swollen gland in my armpit
- A boil in the armpit that keeps coming back
- A tender lump after shaving
- A lump after a vaccine
See a doctor soon if you have
- A lump that is hard, painless, or growing
- A lump that lasts more than three weeks
- A new lump together with a lump or change in the breast
- Fever, night sweats or weight loss with a lump
- A hot, red, very painful swelling with fever (go to the emergency room)
What can cause it
A swollen lymph node
A tender, movable lump after an infection, a cut in the hand or arm, or a vaccine on the same side.
Next step: Wait and recheck; it settles in a few weeks.
Hidradenitis suppurativa
Painful lumps and abscesses that keep coming back in the armpits and groin, with scars. It is not caused by poor hygiene.
Next step: See a doctor; medicines and sometimes surgery.
A boil or an irritated hair follicle
A single red, tender lump, often after shaving or sweating.
Next step: Warm compresses; see a doctor if it does not settle.
A breast cause
A lump in the breast that extends to the armpit, or a hard, painless node.
Next step: See a doctor; breast and armpit ultrasound.
Other causes (uncommon)
A lump that persists, with fever, night sweats or weight loss.
Next step: Examination, scans and a needle sample.
What you can do now
- Do not squeeze the lump
- Avoid shaving and deodorant on a sore lump
- Use a warm compress on a tender boil
- Check your breasts, and tell the doctor about anything you find
- See a doctor if the lump lasts more than three weeks, and note any fever, night sweats or weight loss
Tests your doctor may order
- Examination of the armpit and the breasts
- Ultrasound, and a mammogram when your doctor advises it
- Blood tests, and a needle sample if the lump is suspicious
When is surgery needed?
- Most lumps need no surgery. A boil or an abscess is drained.
- Hidradenitis that keeps coming back can be treated with medicines and, when needed, surgery. See the guide.
- A suspicious node is sampled, and the treatment depends on the result.
Related operation guides
Questions people ask
Is an armpit lump always cancer?
No. Most are swollen lymph nodes reacting to an infection. A lump that is hard, painless, growing or persistent should be checked.
Can a vaccine make my glands swell?
Yes. A vaccine can swell the glands on the same side for a few weeks.
Is hidradenitis caused by poor hygiene?
No. It is a long-term skin disease and is not contagious.
This page gives general information and does not replace the advice of your treating team. In an emergency, go to the nearest emergency room.