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What are the Common Causes of Armpit Swelling?

By Meshell Powell
Updated Mar 03, 2024
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Armpit swelling can be a disturbing symptom with several possible causes. Swollen lymph nodes are the most common reason for swelling in the armpits. Another possible cause may be skin irritation, which may occur from activities such as shaving. Most cysts or lumps that cause swelling are not serious, although certain cancers, especially breast cancer, may sometimes be the reason for this type of swelling. Treatment for this symptom depends on the direct cause of the swelling and may range from no medical treatment at all to the use of prescription medications or surgical intervention.

Swollen lymph nodes are a frequent cause of armpit swelling. The lymph nodes are small, round tissue masses that play a large role in the body's immune system. There are several possible reasons for lymph node swelling, including infections, medical conditions such as lupus, and cancer. A doctor should be consulted so that an accurate diagnosis can be made and proper treatment can begin. Prescription medications may or may not be needed, depending on the cause of the lymph node swelling.

Skin irritation may sometimes lead to swelling in the armpits. This type of irritation may occur from normal activities such as shaving or from friction caused by wearing tight clothing. Physical injuries that affect the hands or arms may also lead to swelling under the arms. Hormonal fluctuations can sometimes lead to irritation and swelling of the armpits.

Infection is a common cause of armpit swelling. In many cases, the infection is caused by illnesses such as the common cold or an infection of the breasts known as mastitis. Treatment with a prescription antibiotic usually clears up the infection, thereby reducing the swelling. In some cases, an infection may develop as the result of an ingrown hair or clogged sweat glands.

Benign masses or cysts frequently cause swelling in the armpits and are more common among women than men. Any unusual lumps or masses should prompt a visit to a doctor just to make sure that a serious medical condition is not present. Blood tests, mammograms, or needle biopsies may be ordered by the doctor to make sure that the lumps are not a cause of concern. Occasionally, certain types of cancer, particularly breast cancer or lymphoma, may be responsible for the swelling. Simple medical procedures can confirm or deny this as a cause of the swelling, and early diagnosis increases the chances of a complete recovery for the patient.

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Discussion Comments

By anon304043 — On Nov 18, 2012

What kind of antibiotic should I drink if I have this armpit cyst?

By anon274613 — On Jun 12, 2012

I have had itching just behind my armpit for four years. Later, the itching spread to the ribs below my armpit and today reaches the nipple of my left breast. It is so bad at night, but not so much during the day. My doctor in Dar es Salaam prescribed sea cucumber jelly but it has not helped. Please assist me.

By LisaLou — On Oct 22, 2011

I was scared when I noticed some swelling under my armpit. I knew this could be a possible sign of breast cancer, so went to the doctor right away.

When they performed a mammogram, they also found a small lump that was close to my armpit. This really had me concerned, and they scheduled a biopsy.

The three days that I had to wait to get the results back seemed like 3 years, but they said it was benign.

I still don't know specifically what caused the swelling in my armpit, but really keep a close eye on them now.

By wavy58 — On Oct 21, 2011

I have a bad tendency to keep using my disposable razors until they absolutely won’t cut hair anymore. Because of this, I have developed an armpit rash on numerous occasions.

When my razor gets dull, I have to go over the area several times to get rid of all the hair. Then, I get raised red bumps that sting when I put deodorant on, and they are irritated by my clothing.

Once this happens, I change my razor, because armpit swelling is very uncomfortable. I have to put alcohol on the bumps for days to make them go away, and I have to deal with the burning in the meantime.

By lighth0se33 — On Oct 21, 2011

@seag47 - I agree with you about going to the doctor whenever you get swollen lymph nodes under your arms. You never know when that could be a symptom of cancer.

My aunt noticed swelling under her arms, but she thought it was because of her razor. She stopped shaving for a week and bought a different kind. However, the swelling persisted.

She was diagnosed with breast cancer. Luckily, it was only in the beginning stage, so it was treatable. If she had waited too long, though, it could have spread. Our bodies have little ways of letting us know when something’s wrong, and we should always listen.

By StarJo — On Oct 20, 2011

I developed swollen armpits after using a new deodorant. I couldn’t find my usual brand in the store, so I bought the next best thing. I ended up being allergic to it.

In addition to the swelling, I developed big red circles under my arms. The entire area was very irritated.

I put aloe vera on it to soothe the burning. I had to go without deodorant for a day to let my armpits recover. I then bought a deodorant formulated for sensitive skin, and it worked fine.

I never would have thought that my armpits could have an allergy. My skin normally doesn’t react to any products that way, so this surprised me.

By seag47 — On Oct 19, 2011

My armpits have swollen before when I’ve had a bacterial infection. The lymph nodes in my neck swelled also, so I didn’t worry when the others joined in.

It hurt to put on deodorant or shave while I was sick. The area was very tender, and even keeping my arms down by my side hurt.

I wound up going to my doctor for some antibiotics, because the infection lingered for too long, in my opinion. Within a day, my armpits returned to normal.

I find that when I’m sick to the point that my armpits swell, it’s best to get treatment. It’s usually something my body has trouble kicking on its own.

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