What Causes a Painful Arm Bump & How to Treat It

A painful bump on the arm can be commonly caused by skin conditions like boils, cysts, warts, or a skin abscess. Less common causes for a painful arm lump under the skin include lipoma or melanoma. Read below for more information on causes and how to treat a painful arm bump.

Symptoms of a Painful Arm Bump

Even if you sit for most of the day at school, work, or during your commute, you're probably still using your arms quite a bit. The arms are among the most used parts of the body. Divided into the upper arm, forearm and the hand, the arms are used for essential activities such as writing, lifting, and moving objects. A painful bump anywhere on the arm can significantly interfere with these tasks.

Common accompanying symptoms of a painful arm bump

A bump may also be associated with symptoms such as:

  • Pain or discomfort
  • Tenderness to the touch
  • Redness
  • Blistering

Less-concerning characteristics

New lumps and bumps on the body are concerning since they can be the initial sign of a cancerous process. However, there are signs and symptoms that are reassuring. Bumps in the arm are less concerning if they have the following characteristics:

  • Soft
  • Easily mobile
  • Get smaller in size with rest

More-concerning characteristics

Painful bumps in the arm that require prompt follow-up have the following characteristics:

  • Hard
  • Fixed/stuck in place
  • Grows in size over time

Make an appointment with your physician if you experience these symptoms in order to get appropriate treatment.

What Causes Painful Arm Bumps?

All of the components discussed above can be injured or inflamed and lead to the development of a painful arm bump.

Traumatic causes

Traumatic causes of a painful arm bump may include the following.

  • Direct: Trauma to the arm from bumping into a wall or a motor vehicle accident can result in a painful arm bump. Traumatic causes may also be associated with visible deformity and bleeding, depending on the severity of the trauma.
  • Repetitive: The arm is used on a daily basis and is susceptible to injury from repetitive movements. Mechanical or anatomical problems with the joints of the shoulder and elbow may result in irritation or a painful bump.

Rheumatologic causes

Rheumatologic causes of a painful arm bump may include the following.

  • Arthritis: Arthritis is a general term for multiple conditions that cause painful inflammation and stiffness throughout the body. Arthritis can result in damage and deformity of the bones and cartilage in the form of nodules.
  • Cysts: Cysts are sacs that can be filled with fluid, air, or other material that can form in any part of the body. Cysts can occur in the arm and cause pain or injury from constant inflammation. The arm is especially susceptible to the formation of cysts given that it has many bursae — small, fluid-filled sacs that help reduce friction in the joints. These bursae can become inflamed, causing pain and a noticeable bump.

Inflammatory causes

Inflammatory causes of painful arm bumps may include the following.

  • Infectious: Some infectious pathogens (mainly bacteria) can infect the bones of the arm resulting in a condition known as osteomyelitis. An infection of the skin can also result in a painful, pus-filled collection called an abscess.
  • Dermatologic: There are many dermatologic conditions that can result in a painful bump on the arm. Panniculitis is a group of inflammatory diseases that affect the fatty tissue under the skin and result in skin nodules.

Malignant causes

In general, any growth is the result of cells dividing and growing uncontrollably. Sometimes there is a genetic mutation in DNA or a specific protein or failure in an important checkpoint. These abnormal cells accumulate to form a noticeable bump. A lump or bump (also known as a tumor) can be benign; however, if this bump grows and invades the body it is considered malignant.

The list below shows results from the use of our quiz by Buoy users who experienced painful arm bump. This list does not constitute medical advice and may not accurately represent what you have.


Lipoma is a word that translates as "fatty tumor," but a lipoma is not cancer. It is simply a growth of fat between the muscle layer and the skin above it.

The exact cause is not known. The condition does run in families and is associated with other unusual syndromes such as adiposis dolorosa, which is similar. Lipomas most often appear after age 40.

Symptoms include a soft, easily moveable lump beneath the skin, about two inches across. A lipoma is painless unless its growth is irritating the nerves around it. They are most often found on the back, neck, and abdomen, and sometimes the arms and upper legs.

It is a good idea to have any new or unusual growth checked by a medical provider, just to make certain it is benign.

Diagnosis is made through physical examination, biopsy, and imaging such as ultrasound or CT scan.

Most of the time, treatment is not necessary unless the lipoma is unsightly or is interfering with other structures. It can be removed through surgery or liposuction.

Rarity: Uncommon

Top Symptoms: skin-colored groin bump, marble sized groin lump, small groin lump

Symptoms that always occur with lipoma: skin-colored groin bump

Urgency: Wait and watch


Melanoma is the most serious type of skin cancer. Often the first sign of melanoma is a change in the size, shape, color, or feel of a mole. Most melanomas have a black or black-blue area. Melanoma may also appear as a new mole. It may be black, abnormal, or "ugly looking."

Rarity: Rare

Top Symptoms: brown-colored skin changes, atypical features of a facial bump, black-colored skin changes, growing facial lump, large facial lump

Symptoms that always occur with melanoma: atypical features of a facial bump

Urgency: Primary care doctor

Boil (furuncle)

A furuncle, also called a boil, is infection of a hair follicle. The infection forms under the skin at the root of the hair and may occur anywhere on the body.

The infection is caused by bacteria, most often Staphylococcus aureus or "staph." Irritation caused by clothes or anything else rubbing the skin can cause the skin to break down and allow bacteria to enter.

Staph bacteria are found everywhere. Frequent and thorough handwashing, and otherwise maintaining cleanliness, will help to prevent its spread.

Most susceptible are those with a weakened immune system; diabetes; and other skin infections.

Symptoms include a single bump under the skin that is swollen, painful, and red, and contains pus.

It is important to treat the boil, since infection can spread into the bloodstream and travel throughout the body.

Diagnosis is made through physical examination and sometimes fluid sample from the boil.

Treatment may involve incision and drainage of the infection, followed by creams to apply to the site of the boil and/or a course of antibiotic medicine.

Rarity: Uncommon

Top Symptoms: pink or red facial bump, small facial lump, painful facial bump, marble sized facial lump, constant skin changes

Symptoms that always occur with boil (furuncle): pink or red facial bump

Symptoms that never occur with boil (furuncle): fever

Urgency: Self-treatment

Skin cyst

A cyst is a small sac or lump, filled with fluid, air, fat, or other material, that begins to grow somewhere in the body for no apparent reason. A skin cyst is one that forms just beneath the skin.

It's believed that skin cysts form around trapped keratin cells – the cells that form the relatively tough outer layer of the skin.

These cysts are not contagious.

Anyone can get a skin cyst, but they are most common in those who are over age 18, have acne, or have injured the skin.

Symptoms include the appearance of a small, rounded lump under the skin. Cysts are normally painless unless infected, when they will be reddened and sore and contain pus.

Diagnosis is made through physical examination. A small cyst can be left alone, though if it is unsightly or large enough to interfere with movement it can be removed in a simple procedure done in a doctor's office. An infected cyst must be treated so that the infection does not spread.

Rarity: Common

Top Symptoms: skin-colored armpit bump, marble sized armpit lump, small armpit lump

Symptoms that always occur with skin cyst: skin-colored armpit bump

Urgency: Wait and watch

Basal cell carcinoma

Basal cell carcinoma is a slow-growing form of skin cancer. Skin cancer falls into two major groups: Non-melanoma and melanoma. Basal cell carcinoma is a type of non-melanoma skin cancer.

Rarity: Uncommon

Top Symptoms: facial skin changes, pink or red facial bump, small facial lump, painless facial bump, growing facial lump

Urgency: Primary care doctor

Skin abscess

A skin abscess is a large pocket of pus that has formed just beneath the skin. It is caused by bacteria getting under the skin, usually through a small cut or scratch, and beginning to multiply. The body fights the invasion with white blood cells, which kill some of the infected tissue but form pus within the cavity that remains.

Symptoms include a large, red, swollen, painful lump of pus anywhere on the body beneath the skin. There may be fever, chills, and body aches from the infection.

If not treated, there is the risk of an abscess enlarging, spreading, and causing serious illness.

Diagnosis is made through physical examination.

A small abscess may heal on its own, through the body's immune system. But some will need to be drained or lanced in a medical provider's office so that the pus can be cleaned out. Antibiotics are usually prescribed.

Keeping the skin clean, and using only clean clothes and towels, will help to make sure that the abscess does not recur.

Rarity: Common

Top Symptoms: rash with bumps or blisters, red rash, red skin bump larger than 1/2 cm in diameter, pus-filled rash, rash

Symptoms that always occur with skin abscess: rash with bumps or blisters

Urgency: Primary care doctor


Pimples are also called comedones, spots, blemishes, or "zits." Medically, they are small skin eruptions filled with oil, dead skin cells, and bacteria.

Pimples often first start appearing at puberty, when hormones increase the production of oil in the skin and sometimes clog the pores.

Most susceptible are teenagers from about ages 13 to 17.

Symptoms include blocked pores that may appear flat and black on the surface, because the oil darkens when exposed to the air; blocked pores that appear white on the surface because they have closed over with dead skin cells; or swollen, yellow-white, pus-filled blisters surrounded by reddened skin.

Outbreaks of pimples on the skin can interfere with quality of life, making the person self-conscious about their appearance and causing pain and discomfort in the skin. A medical provider can help to manage the condition, sometimes through referral to a dermatologist.

Diagnosis is made through physical examination.

Treatment involves improving diet; keeping the skin, hair, washcloths, and towels very clean; and using over-the-counter acne remedies.

Rarity: Common

Top Symptoms: pink or red facial bump, small facial lump, painful facial bump, marble sized facial lump

Symptoms that always occur with pimple: pink or red facial bump

Urgency: Self-treatment

Severe skin abscess

A skin abscess is an infection of the deeper skin that's typically due to bacteria seen on the skin. Recently, infections are more frequently caused by Staph. Aureus (puts the "staph" in "staph infections"). If the infection begins to spread, urgent treatment is required.

Rarity: Rare

Top Symptoms: fatigue, fever, painful neck lump, marble-size neck lump, pink or red neck bump

Symptoms that always occur with severe skin abscess: pink or red neck bump, red bump

Urgency: Hospital emergency room

Worried about a condition?

Take a thorough self-assessment of your symptoms to find the cause.

Free, private, and secure

Powered by advanced Buoy Assistant AI, learn more.

Painful Arm Bump Treatments and Relief

At-home treatments

In the meantime, resting, elevating, and icing your arm along with using compression bandages may also help alleviate swelling and discomfort. If your painful arm bump goes away with these supportive measures, your condition is most likely not life-threatening.

When to see a doctor

If your painful arm bump persists or worsens, it is important to make an appointment as soon as possible. You should continue to monitor the bump and make sure to alert your medical provider of any changes. Depending on the cause of your symptoms, your physician may suggest:

  • Surgery: This is the first-line option for removing both benign and malignant growths from the arm and other parts of the body.
  • Pain medication: Medications such as NSAIDs (non-steroidal anti-inflammatory agents) that help alleviate the pain associated with painful arm bumps are often used to help treat this condition.
  • Anti-inflammatory: Inflammatory causes of painful arm bumps can be treated with various types of medications that target and decrease inflammation, including immune system suppressing drugs.
  • Cancer treatment: If your painful arm bump and associated symptoms are due to malignant cancer, your physician will discuss treatment options including surgery, radiation or chemotherapy.

When it is an emergency

You should seek immediate medical attention if you have the following:

  • Severe difficulty moving the arm
  • Severe arm numbness, warmth, or color changes
  • High fever
  • Severe, sudden, or worsening pain and/or swelling of the area
  • Nausea and/or vomiting

FAQs About Painful Arm Bump

Will the bump on my arm go away on its own?

Depending on the cause, there is a possibility that the bump and the accompanying pain will go away on its own. If the arm bump is a cyst or caused by trauma or repetitive injury, the likelihood that it will go away on its own is high. However, if the arm bump is a benign or malignant tumor, it will not resolve on its own and will require follow-up.

How will the bump affect my daily activities?

An arm bump can be very painful and uncomfortable, but those related to temporary causes should not affect your day-to-day in the long-term. After a traumatic event, bed rest and limited activity with the affected arm will help with recovery. An arm bump associated with a benign or malignant growth may cause fatigue or unexplained weight loss. See a medical provider promptly if you feel like your symptoms are significantly affecting your life.

What is elbow bursitis?

Elbow bursitis is inflammation or irritation of the olecranon bursa — a thin, fluid-filled sac located at the bony part of the elbow (olecranon). See a visual representation of this condition here. With inflammation, the bursa fills with fluid, causing pain and limitation of movement. Elbow bursitis can be caused by trauma, prolonged pressure, infection, and some medical conditions such as arthritis.

Can a painful bump on my arm be cancer?

There is a possibility that a new painful bump on the arm is cancer; however, there are certain signs and symptoms that can be reassuring. Bumps in the arm are less concerning if they have the following characteristics: soft, easily mobile, get smaller with rest or over the course of the day. Painful bumps in the arm that require prompt follow-up include the following characteristics: hard, fixed/stuck in place, irregular, grows in size over time.

What can I do to prevent the development of painful arm bumps?

It is very difficult to prevent the development of painful arm bumps. The only situations in which the development of forearm bumps may be prevented are those related to environmental factors such as bug bites. There are several strategies to prevent bites, such as using wearing protective clothing, using insect repellent, and going outside at times when mosquitoes are less active.

Questions Your Doctor May Ask About Painful Arm Bump

  • What color is the bump?
  • Any fever today or during the last week?
  • Are you experiencing a headache?
  • Do you have a rash?

Self-diagnose with our free if you answer yes on any of these questions.

Share your story
Was this article helpful?
Read this next
Slide 1 of 1


  1. Panniculitis, Idiopathic Nodular. National Organization for Rare Disorders. NORD Link
  2. Elbow (olecranon) bursitis. American Academy of Orthopedic Surgeons: OrthoInfo. Reviewed March 2018. OrthoInfo Link
  3. Medial epicondylitis – golfer’s elbow. U.S. National Library of Medicine: Medline Plus. Updated November 13, 2018. MedlinePlus Link
  4. Lumps on forearm: Photo rounds. The Journal of Family Practice. 2015;64(5). MDedge Link
  5. Schweitzer WJ, Goldin HM, Bronson DM, et al. Solitary hard nodules on the forearm. JAMA Dermatology. 1989;125(6):831-2. JAMA Link