Armpit lump

Overview

An armpit lump is a swelling or bump that appears under your arm. It can be caused by many things, most commonly swollen lymph nodes (small bean-shaped glands that help fight infection), a cyst (a fluid-filled sac), or a skin infection. Most armpit lumps are not serious, but a few may need medical attention.

Yes, armpit lumps are very common. Almost everyone will have one at some point, often due to a minor infection or irritation.

Anyone can get an armpit lump, from children to older adults. They are more common in people with recent infections, skin conditions, or those who shave their underarms.

Symptoms

Common symptoms

• A visible or feelable bump under the arm
• The lump may be tender, painful, or painless
• Redness or warmth over the lump
• Swelling in the armpit area

Symptoms in children

• Swollen lymph nodes often after a cold, ear infection, or vaccination
• A painful, red lump that may be a boil or abscess
• Fever or general feeling of being unwell

Symptoms in older adults

• A firm, painless lump that slowly grows
• Lump that feels fixed (does not move easily when pushed)
• Unexplained weight loss, night sweats, or persistent fever

Causes

Main causes

• Swollen lymph nodes (lymphadenopathy) from infections like colds, flu, strep throat, or skin infections
• Cysts (benign fluid-filled sacs) that form in the skin or deeper tissues
• Lipomas (harmless fatty lumps)
• Skin infections such as boils, abscesses, or hidradenitis suppurativa (chronic inflammation of sweat glands)
• Reaction to vaccines (especially COVID-19, flu, or shingles vaccines)
• Less commonly: lymphoma (cancer of the lymph nodes), breast cancer that has spread to armpit lymph nodes, or other cancers

Risk factors

• Recent infection or illness
• Shaving or waxing underarms (can cause small cuts and infections)
• Heavy use of antiperspirants or deodorants (may irritate skin)
• Weakened immune system (from conditions like diabetes or HIV)
• Family history of breast cancer or lymphoma

When to see a doctor

See a doctor urgently if:

• Lump that grows quickly over a few days
• Lump that feels hard, irregular, or fixed to the skin or deeper tissue
• Lump accompanied by unexplained weight loss, drenching night sweats, or persistent fever
• Red, hot, painful lump with fever (may be an abscess)

Book a routine appointment if:

• Lump that lasts longer than two weeks without improving
• Lump that changes in size or texture
• Lump that causes concern, even if painless
• Multiple lumps in the armpit or elsewhere

Diagnosis

Your doctor will ask about your symptoms, medical history, and examine the armpit lump. They will feel the lump to check its size, texture, and whether it moves. They may also check for other swollen lymph nodes in your neck, groin, or elsewhere.

Tests that may be done

• An ultrasound scan (uses sound waves to create an image of the lump) to see if it is solid or fluid-filled
• Blood tests to look for signs of infection or inflammation
• If needed, a needle biopsy (taking a small sample of cells from the lump) to check for cancer cells

What to expect at your appointment

The examination is quick and not painful. If an ultrasound or biopsy is recommended, your doctor will explain the procedure and any risks. Results may take a few days. Most tests come back showing the lump is harmless, giving you reassurance.

Treatment

Treatment depends on the cause of the lump. Many lumps need no treatment at all and go away by themselves. If an infection is present, treatment may involve antibiotics or draining an abscess. For lumps that are cysts or lipomas, removal is usually only done if they cause discomfort or for cosmetic reasons. If a serious condition like cancer is found, your doctor will refer you to a specialist for further care.

Self-care at home

• Apply a warm compress (a clean cloth soaked in warm water) to the lump for 10–15 minutes, three times a day to help reduce swelling and pain
• Keep the area clean and dry
• Avoid squeezing or poking the lump, as this can cause infection to spread
• If the lump is from a skin infection, stop shaving or using deodorant on that side until it heals

Medical treatments

If a bacterial infection is diagnosed, your doctor may prescribe antibiotics (usually taken by mouth). For an abscess (a collection of pus), a doctor may need to make a small cut to drain it. For benign lumps like large lipomas or cysts that are painful or unsightly, a minor surgical removal can be done under local anaesthetic. If cancer is detected, treatment options will be discussed with a cancer specialist and may include surgery, radiation therapy, or systemic treatments such as chemotherapy or targeted therapy – your doctor will explain the best plan for your situation.

When is surgery considered?

Surgery is usually only needed if the lump is an abscess that needs draining, or if a benign lump causes pain or discomfort, or if a biopsy shows cancer. In cancer cases, surgery to remove the lump and nearby lymph nodes may be part of the treatment.

Living with this condition

Most people with a harmless armpit lump can continue their normal activities. You may need to avoid wearing tight clothing or using irritating deodorants while the lump heals. If you have a lump that is being watched by your doctor, keep an eye on it and note any changes.

Lifestyle tips

• Use mild, fragrance-free deodorants or antiperspirants to reduce irritation
• Shave carefully with a clean razor to avoid cuts and infections
• Maintain good skin hygiene: wash underarms daily with mild soap
• If you have hidradenitis suppurativa, avoid smoking and maintain a healthy weight to reduce flare-ups

Diet and exercise

No specific diet is needed for most armpit lumps. A healthy, balanced diet and regular exercise help your immune system stay strong. If you have an infection, drinking plenty of water and resting may help recovery.

Mental health and emotional wellbeing

Finding a lump can be worrying. It is normal to feel anxious, especially while waiting for a diagnosis. Try to avoid jumping to worst-case conclusions – remember that most lumps are harmless. Talk to your doctor about your concerns; they can provide reassurance and information.

Prevention

Not all armpit lumps can be prevented, but you can reduce your risk of infection-related lumps by keeping the skin clean, avoiding cuts from shaving, and treating any skin infections promptly. A healthy lifestyle supports your immune system.

Vaccines

Vaccines, such as the flu vaccine and COVID-19 vaccine, can prevent infections that sometimes cause swollen lymph nodes. It is normal for lymph nodes to swell temporarily after a vaccination – this is a sign your body is building protection.

Screening programmes

There is no routine screening for armpit lumps. However, if you have a family history of breast cancer, your doctor may recommend regular breast checks or mammograms (breast X-rays), which can also detect changes in the armpit area.

Complications

If left untreated

• A small infection can spread and become a larger abscess that requires drainage
• An untreated abscess can lead to a skin infection that spreads to deeper tissues (cellulitis) or even into the bloodstream (sepsis, which is serious)
• Rarely, a cancerous lump left untreated can grow and spread to other parts of the body

Long-term outlook

The outlook is usually excellent. Most armpit lumps are harmless and go away on their own or with simple treatment. Even when lumps are caused by more serious conditions, early detection and modern treatments offer very good chances for recovery. If you have any concerns, seeing your doctor is the first positive step.

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