The short explanation
A painless armpit lump that has stayed for a month and is growing should be examined by a doctor soon, within a week or two. Many armpit lumps are swollen lymph nodes reacting to an infection, cysts or fatty lumps called lipomas. But lymph nodes in the armpit also drain the breast, so a lump that is persistent, firm or growing is checked carefully, even if the breasts feel normal. A family physician, a general surgeon or a breast clinic can all start the assessment. If you are unsure, begin with whoever you can see soonest.
What depends on your situation
The parts of this that change from woman to woman. Uncertainty is stated, not hidden.
- The doctor will feel both armpits, both breasts, the neck and above the collarbones, and ask about recent infections, skin problems on that arm, vaccinations, fever, night sweats, weight loss and tiredness.
- An ultrasound of the armpit is usually the first test. Depending on your age and the findings, a mammogram, blood tests or a needle sample of the lump may follow.
- Some causes, like a skin infection or a recent vaccine in that arm, make nodes swell for a few weeks and then settle. A lump that keeps growing does not fit that pattern.
What this answer cannot determine
The boundary of online education. These need a clinician who can see you.
- This cannot tell you what the lump is. Examination and imaging, and sometimes a needle test, are what decide it.
Questions for your clinician
Take these with you. You can add any of them to an appointment card.
- Is this a lymph node, and what might be making it swell?
- Do I need an ultrasound, a mammogram or both?
- Should a needle sample be taken?
- Should any blood tests be done?
When to seek help
Clinician-approved guidance for this topic. When in doubt, being seen is never the wrong choice.
Book an appointment soon
- See a clinician within a week or two for an armpit lump that has lasted more than a few weeks or is getting bigger.
Raise it at a routine appointment
- Bring a note of when you first noticed the lump and any changes in size. You can ask for a woman doctor for the examination, and you can bring someone you trust into the room with you.
Sources
The evidence this explanation is built on.
- Breast cancer — symptoms NHS
- Breast diseases MedlinePlus (NIH)
- Breast cancer MedlinePlus (NIH)
Who wrote and reviewed this
Every AskHer answer names its author. A clinically reviewed answer also names the clinician who signed it off — if no clinician is named below, it has not been clinically reviewed.
- Author
- AskHer Editorial (AI-assisted draft) AskHer's editorial team — not an individual clinician Works in English, தமிழ், हिन्दी
- Clinical reviewer
- Nobody yet No clinician has signed this answer off, and no person on the editorial team has read it yet. That is what the “Written with AI assistance” label means. It is queued for an editor to read, and then for a clinician who works in this area. The sources it was drafted against are listed above.
- Review status
- Written with AI assistance — not yet reviewed by a person
- Last reviewed
- Not yet reviewed by a person
- Version
- 1
Correction history
Substantive changes are listed, not quietly edited away.
No corrections have been made since this answer was first published.
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