Lump under armpit
Key facts
- You have lymph glands in your armpit that can sometimes swell and make a lump.
- Your lymph glands may swell when you have an infection, an inflammatory disease or cancer.
- See your doctor if you have lumps under your arm that do not go away after 3 weeks or longer.
- Treatment for an underarm lump depends on the cause, and you may need blood tests to help determine it.
- To help prevent a lump under your armpit, you can self-monitor for cancer, wash your hands often and avoid risky behaviours to prevent infections.
What is a lump under the armpit?
A lump under the armpit is a swelling or mass that you can feel beneath the skin under your arm.
The lump may be:
- soft or firm
- mobile (moves under your skin) or fixed (does not move)
- painful or painless
A lump under your armpit may happen together with other symptoms, such as redness, warmth, or feeling generally unwell.
The medical name for a lump under your armpit is axillary lymphadenopathy. It can happen when you have an infection.
You might feel a lump or swelling when you are washing yourself or monitoring yourself for breast cancer.
A common reason for a lump under your armpit is enlarged (swollen) lymph nodes (glands). Normal lymph nodes measure less than 1cm.
What symptoms are related to a lump under the armpit?
If you have swollen glands in your armpit, you might have an infection such as glandular fever or tonsillitis. Some symptoms of viral or bacterial infections are:
- fever (a temperature of 38℃ or above) or chills
- sore throat
- tiredness
- cough and runny nose
- rash
- weight loss
If the lump under your arm is caused by a skin condition, you may have lumps on other parts of your body too.
If you have an inflammatory disease, you may have other symptoms such as muscle or joint pain.
CHECK YOUR SYMPTOMS — Use the Symptom Checker and find out if you need to seek medical help.
What causes a lump under the armpit?
Some causes of swollen lymph nodes (swollen glands) in your armpit are:
- infection with a virus
- infection with bacteria
- breast cancer
- blood cancer such as leukaemia
- lymphoma (cancer of the lymphatic system)
- sarcoidosis or lupus (inflammatory diseases)
The most common cause of a lump in your armpit is an infection. When you have an infection, your body makes more white blood cells in your glands. White blood cells help your body kill the virus or bacteria. Your lymph glands get bigger when they are making extra white blood cells.
Cancer is a rare cause of swollen glands under your arm.
Here are some other things that can cause a lump under your armpit:
- lipomas — lumps made of fatty tissue that usually appear on your chest, back, shoulders, arms or neck
- cysts — sacs filled with fluid under your skin
- boils — painful red lumps filled with pus
- hidradenitis suppurativa — an uncommon skin condition that causes painful lumps
- medicines — taking certain medicines such as phenytoin, allopurinol or some antibiotics
How is the cause of a lump under the armpit diagnosed?
Your doctor will examine you and ask you how long you have had the lump in your armpit. They will look at the number of lumps you have and their:
- size
- location
- shape
- texture (how they feel)
Your doctor might do a throat swab or send you for some blood tests to work out the cause. They might want to check:
- how many white blood cells you have — this is a way to check if you have an infection
- your full blood count — this can help check your general health
- your liver health — this is a way to check if the cause relates to medicines
You might need a chest x-ray or other medical imaging tests.
You may also need to have a biopsy. This is when your doctor takes a small sample from the lump with a needle. The sample is then sent to a laboratory for testing. You will have a local anaesthetic to numb any pain during a biopsy.
When should I see my doctor?
If you have lumps under your arm and they are bothering you, show them to your doctor.
Swollen lymph glands during an infection should go down as you get better.
If you still have swollen lymph nodes after 3 weeks or longer, see your doctor.
When to seek urgent care for lumps under the arm
Seek urgent care if you have sudden weight loss and feel very tired. Some other warning signs for a serious illness are excessive sweating or unexpected bruising or bleeding.
FIND A HEALTH SERVICE — The Service Finder can help you find doctors, pharmacies, hospitals and other health services.
How is a lump under the armpit treated?
The treatment will depend on the cause of the lump.
Self-care at home
If you have an infection, such as a cold or flu, rest at home and make sure you drink plenty of fluids.
You can take over-the-counter medicines to help with cold and flu symptoms.
Your doctor will choose a medicine based on the cause of your condition.
If you have:
- a bacterial infection, your doctor may prescribe a course of antibiotics
- shingles or another viral infection, you may need antiviral medicine
- an inflammatory disease, your doctor or specialist will recommend a treatment plan that might include medicines
- cancer, you will need to see an oncologist or haematologist for advice and treatment
- a skin problem that is not getting better, you may be referred to a dermatologist (skin specialist) who can prescribe the medicine you need
What are the complications of a lump under the armpit?
A lump under your armpit could be a sign of a serious condition, such as:
Can a lump under the armpit be prevented?
You should go for routine health checks and screening to help pick up any problems with your health early.
If you have a serious condition like cancer, it's best to find out as soon as you can, so that you can start treatment.
You can prevent some infections that may cause a lump in your armpit. Glandular fever is spread through saliva, so avoid kissing someone that is unwell. Wash your hands regularly.
You can also ask your doctor if your vaccinations are up to date. You can get a vaccine to prevent many infections.
If you inject illicit drugs, make sure you always use clean needles. Serious infections like HIV and hepatitis B and C are spread through shared injecting equipment. Protect yourself from sexually transmitted infections by using condoms.
Resources and support
Read another healthdirect article on how to protect yourself from serious blood-borne viruses, such as HIV, which can cause swollen lymph nodes.
Find out about lymphoma from Cancer Australia. Their information on lymphoma care can be found through Health Translations in several languages other than English.
Go to Breast Screen Australia for information about breast cancer checks.
You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with 24 hours a day, 7 days a week.
Learn more here about the development and quality assurance of healthdirect content.
Last reviewed: August 2025
