Armpit lump: 10 main causes and what to do

armpit lump

The lump in the armpit may arise due to inflammation or infection, as in the case of folliculitis, furuncle, suppurative hydrosadenitis, or infectious mononucleosis, or be indicative of a tumor, such as breast cancer or lymphoma, for example.

Depending on its cause, a lump in the armpit may be accompanied by other symptoms, such as an increase in local temperature, redness and sensitivity to the touch, formation of pus, fever, weight loss or night sweats.

In the presence of a lump in the armpit, it is important to consult the general practitioner or dermatologist, so that its characteristics and symptoms are evaluated, and, thus, it is possible to identify the cause and initiate the most appropriate treatment, which can be done with the use of antibiotics, anti-inflammatories or surgery, for example.

Main causes of armpit lump

The main causes of armpit lumps are:

  1. Folliculitis

Folliculitis is inflammation in the hair follicle, which is the structure in the skin where the hair root is located, making it difficult for the hair to come out on the surface of the skin, and leading to the appearance of symptoms, such as one or several small pimples in the armpit, which can be painful, reddish or yellowish, due to the presence of pus, and cause itching.

Armpit folliculitis, also known as ingrown hair, is a relatively common situation, and is usually caused by friction of the skin when wearing tight clothes or after shaving the hair with a razor or waxing, but it can also happen due to an infection by bacteria or fungi.

What to do : folliculitis can be treated at home by cleaning the armpit with antiseptic soap, but it may also be necessary to use anti-inflammatory drugs, creams, ointments or antibiotic pills to fight the infection, which should be recommended by the dermatologist. It may also be indicated to avoid shaving or shaving the skin until inflammation improves.

  1. Boil

The boil is also caused by infection at the root of the hair follicle, however, it is deeper and causes inflammation of the surrounding area, causing a larger, redder lump and producing a large amount of pus.

This pus-filled lump that can grow over time, causing pain, increased local temperature, redness and sensitivity to touch, and occur in the armpit region or any other region of the body that sweats a lot or suffers greater friction.

What to do : It is necessary to seek medical help to assess the region and indicate whether the furuncle should be drained. You can also guide antibiotics in ointment or pill, in addition to warm water compresses to speed up recovery.

During the treatment of the boil, and to prevent new infections, it may be indicated to use antiseptic soap, wash with soap and water daily and after bursting, in addition to washing with boiling water the clothes that are in contact with the region. You should never squeeze the boil, as this can worsen the inflammation and infection, making it more difficult to treat.

  1. Hidradenitis suppurativa

Hidradenitis suppurativa of the armpit is the inflammation of the glands that produce sweat in this region, causing the blockage of the passage of sweat out of the gland and the formation of painful lumps that leave scars on the skin.

What to do : It is necessary to evaluate the dermatologist, who will indicate treatments to reduce the symptoms of the affected region, such as creams with antibiotics or injection of corticosteroids in the armpit. In the most severe cases, surgery may be required to remove the affected area and replace it with a graft.

Keeping the region clean, avoiding the use of tight clothes and making warm compresses in the region can also help with the treatment.

  1. Sebaceous cyst

The sebaceous cyst is a lump that forms under the skin, rounded in shape, measuring a few centimeters, but which can increase in size over time, and can be hard or soft, and move during palpation, and can appear in the armpit. or any other region of the body.

This type of cyst is benign, caused by an obstruction in the sebaceous gland, which causes sebum to accumulate under the skin, and usually does not cause symptoms. However, when it becomes inflamed or infected, it can cause pain, an increase in temperature in the area, tenderness or redness.

What to do : the treatment must be indicated by the dermatologist, and consists of compressing the area with warm water for 15 minutes and using anti-inflammatories. In case of inflammation or infection of the cyst, the doctor can drain it and indicate the use of antibiotics.

  1. Tongue

The ingua is the enlarged lymph node, which can arise due to any inflammation or infection of the arm, chest or breast region. This happens because the lymph node is part of the immune system, and can increase in size to produce more defense cells to attack any germs that could bring problems to the body.

In most cases, it is not a cause for concern, and can arise from various causes, such as an ingrown hair, folliculitis, furuncle, lymphadenitis, but it can also indicate a systemic disease, such as lupus, rheumatoid arthritis, dermatomyositis or sarcoidosis or cancer, especially when they grow a lot or are located in various parts of the body.

What to do:  the treatment should be carried out with guidance from the general practitioner, according to the cause of the inflammation in the lymph node, and the use of anti-inflammatory drugs, antibiotics, antivirals, corticoids or biological therapy, for example, may be indicated. In case it was caused by cancer, surgical removal of the ganglion or tumor that is causing its swelling may be recommended, in addition to chemotherapy or radiotherapy sessions.

  1. Allergies

Allergy is an inflammatory reaction that arises due to an exaggerated response of the immune system to substances such as deodorants, creams, or even the fabric of clothing, for example, leading to the appearance of a lump in the armpit, irritation, intense itching, balls or reddish spots. in the skin.

What to do: try to identify the cause of the allergy, and thus, avoid exposure to the substances that trigger them. If the symptoms do not improve, consult a dermatologist who can perform an allergy test to identify the type of substance that is causing the symptoms and, if necessary, indicate treatment with antiallergic drugs or corticoids.

  1. Infections

Some infections, such as HIV infection , herpes simplex or mononucleosis , can cause enlargement of the lymph nodes, and the appearance of a lump in the armpit or in other regions of the body, such as the neck and nape of the neck.

What to do: consult your general practitioner or infectologist so that diagnostic tests can be carried out to identify the type of infection and thus initiate the most appropriate treatment, which may include the use of antiretrovirals, in the case of HIV, antivirals, such as acyclovir or valacyclovir, in the case of herpes simplex, or the use of analgesics or anti-inflammatories to reduce swelling and fever, in the case of mononucleosis, for example.

  1. Lipoma

Lipoma is a round and soft lump, which forms under the skin and is composed of fat cells, and can appear in the armpit, neck, back, shoulders or anywhere in the body where fat cells are present.

Generally, the lipoma does not cause pain, however, in some cases it can grow and press the surrounding nerves and cause pain and even inflammation with symptoms of redness or increased temperature at the site.

What to do: Generally, no treatment is needed for the lipoma, however, when the lipoma is very large or causes discomfort, the dermatologist may perform surgery to remove it.

  1. Breast cancer

Breast cancer is one of the main types of cancer that affect women, but it can also affect men, and although in the early stages breast cancer does not cause symptoms, the main sign that can indicate the presence of the tumor is the palpation of a hardened lump in the breast.

In addition, other symptoms may be present, such as swelling, lump formation in the armpit or pain that can radiate to the arm, redness, discharge from the nipples or sore breasts, for example.

What to do: in the presence of any alteration in the breast, you should consult the mastologist, so that tests can be carried out to diagnose breast cancer, and start the most appropriate treatment that can be done with surgery, chemotherapy, radiotherapy, hormone therapy or biological therapy, for example.

In addition, breast cancer can be cured, depending on the type and stage it is in, so prevention is very important, through breast self-examination and mammography. Understand the  step-by-step on how to do the breast self-exam correctly .

  1. Lymphoma

The lump in the armpit can arise due to lymphoma, which is a type of cancer of the lymph nodes, leading to the appearance of a hard lump in the armpit, which does not disappear after 1 or 2 months and does not stop growing.

Generally, in this type of cancer, other symptoms may be present in addition to the lump in the armpit, such as fever, night sweats, excessive tiredness and weight loss for no apparent reason.

What to do: you should consult your general practitioner, hematologist or oncologist so that blood tests, tomography or PET-CT can be performed, for example, to identify the type of lymphoma, and start the most appropriate treatment, which usually it is done with chemotherapy or radiotherapy.

Abbas Jahangir

I am a researcher and writer with a background in food and nutritional science. I am the founder of, our reputable online platform offering scientifically-backed articles on health, food, nutrition, kitchen tips, recipes, diet, and fitness. With a commitment to providing accurate and reliable information, we strive to empower our readers to make informed decisions about their health and lifestyle choices. Join us on's journey toward a healthier and happier lifestyle.

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