Read below about swelling of one arm, including causes, treatment options and remedies. Or get a personalized analysis of your swelling of one arm from our A.I. health assistant. At Buoy, we build tools that help you know what’s wrong right now and how to get the right care.

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Swelling of One Arm Symptoms

Since the arms are used for so many activities of daily life, a problem is unlikely to go unnoticed for long. Swelling of one arm can interfere with mobility and strength, particularly if other symptoms like pain are also present. There are multiple types of structures that drain fluid out of the arm: the venous system drains blood on its way back to the heart, and the lymphatic system drains cellular waste fluid. Blockage of the venous or lymphatic system in one arm can cause a backup of fluid, leading to swelling. Problems with the elbow joint can also cause swelling.


Depending on the cause, arm swelling can be associated with the following additional symptoms:

Swelling of One Arm Causes Overview

Swelling of one arm is typically caused by a local problem since systemic diseases associated with swelling will affect both arms and likely other parts of the body as well. Unilateral arm swelling can result from a problem with venous or lymphatic drainage; a local infection or inflammatory reaction; or an injury.

Venous problems

Problems in the veins can lead to swelling of one arm, such as the following.

  • Blood clot: A clot in one of the deep veins (deep vein thrombosis or DVT) of the arm can cause swelling, often accompanied by pain and redness. Arm clots are uncommon but can occur in the setting of vascular trauma, such as when a pacemaker or catheter is present[1]. A clot may be complicated by chronic arm swelling [2].
  • Compression: Compression of the large subclavian vein near the neck can obstruct venous drainage, leading to swelling and blue discoloration of the arm. Tingling in the fingers is often present as well due to hand swelling and/or nerve compression [3]. Anatomic abnormalities such as an extra rib are the primary cause. Subclavian vein compression is the primary cause of deep venous clots in the arm in the absence of catheters or other devices[2].

Lymphatic problems

Damage to the arm's lymphatic drainage system or mechanical blockage can cause a backup of lymph fluid (lymphedema). Tumors, lymph node surgeries, and certain infections can cause lymphedema and swelling in one arm[4,5]. Removal of lymph nodes in the armpit as part of breast cancer treatment is a particularly common cause of upper extremity lymphedema [6].

Inflammatory reaction

Inflammatory causes can lead to swelling of one arm, such as the following.

  • Vaccination: Rarely, swelling of the arm can be observed after receiving multiple doses of a childhood vaccine (DTaP) [7].
  • Insect bites: Most people will experience some degree of swelling with an insect bite on the arm. Those who have an allergy can have a larger amount of swelling, extending as much as 10 inches beyond the site of the bite [8].


Injuries can result in swelling of one arm in regards to the following.

  • Overuse injuries: Biceps tendinitis and acute injuries such as a fracture can cause swelling of the arm along with pain.
  • Chronic pain syndrome: An injury to the arm can be followed by a chronic pain syndrome characterized by pain, swelling, abnormal temperature sensation, and changes in the appearance of the skin[9].


An infection of the skin and deeper tissues of the arm will result in swelling, redness, and warmth.

A.I. Health Assistant Causes for Swelling of One Arm

The list below shows results from the use of our A.I. Health Assistant by Buoy users who experienced swelling of one arm. This list does not constitute medical advice.

  1. 1.Repetitive Strain Injury of the Upper Arm

    Repetitive strain injury of the upper arm is caused by consistent repetitive use.

    Resolves with rest

    Top Symptoms:
    upper arm pain from overuse, upper arm weakness, upper arm numbness
    Symptoms that always occur with repetitive strain injury of the upper arm:
    upper arm pain from overuse
    Symptoms that never occur with repetitive strain injury of the upper arm:
    upper arm injury, severe upper arm pain
  2. 2.Deep Vein Thrombosis

    Deep vein thrombosis (DVT) is a blood clot that forms in a vein deep in the body. Most deep vein clots occur in the lower leg or thigh.

    Curable with medication or surgery but may recur.

    Top Symptoms:
    fever, thigh pain, upper leg swelling, calf pain, butt pain
    Hospital emergency room
  3. 3.Cellulitis

    Facial cellulitis is a skin infection that typically comes from other parts of the face like the mouth or the sinuses and needs antibiotic treatment. Symptoms can be pain, redness, warmth and swelling of the affected area.

    Dependent on severity of infection

    Top Symptoms:
    fever, chills, facial redness, swollen face, face pain
    Symptoms that always occur with cellulitis:
    facial redness, area of skin redness
    Primary care doctor
  4. 4.Compartment Syndrome

    Compartment syndrome is a serious condition that involves increased pressure in a muscle compartment. It can lead to muscle and nerve damage and problems with blood flow.

    Prognosis is highly variable after surgery and depends on how rapidly you are treated.

    Top Symptoms:
    arm numbness, hand numbness, foot numbness, pain in one leg, thigh numbness
    Hospital emergency room

    Swelling of One Arm Checker

    Take a quiz to find out why you’re having swelling of one arm.

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  5. 5.Bicep Bruise

    A bruise is the damage of the blood vessels that return blood to the heart (the capillaries and veins), which causes pooling of the blood. This explains the blue/purple color of most bruises. Bruises of the bicep are common due to minor injuries.

    Bruises tend to begin healing within one week.

    Top Symptoms:
    constant upper arm pain, recent bicep injury, pain in one bicep, swelling of one arm, upper arm bruise
    Symptoms that always occur with bicep bruise:
    recent bicep injury, constant upper arm pain
  6. 6.Bruised Tricep

    A bruise is the damage of the blood vessels that return blood to the heart (the capillaries and veins), which causes pooling of the blood. This explains the blue/purple color of most bruises. Bruises of the tricep are common, often due to minor injury.

    Bruises tend to begin healing within one week.

    Top Symptoms:
    constant upper arm pain, tricep injury, pain in one tricep, swelling of one arm, upper arm bruise
    Symptoms that always occur with bruised tricep:
    tricep injury, constant upper arm pain
  7. 7.Benign Bony Growth (Osteochondroma)

    An osteochondroma is a non-cancerous growth that usually develops during childhood or adolescence. It is a benign tumor that forms on the surface of a bone near the growth plate.

    Will remain for life if not treated with surgery, but is benign and is not expected to affect life expectancy.

    Ultra rare
    Top Symptoms:
    lower leg bump, upper leg bump, numbness in one thigh, painful thigh lump, hip bump
    Primary care doctor
  8. 8.Chronic Upper Arm Bone Infection (Osteomyelitis)

    Osteomyelitis of the upper arm is a bacterial or fungal infection of the bone, typically caused by Staph Aureus (40-50% of the time). It is difficult to diagnose as the infection can come from a break in the skin at the area or anywhere else in the body that spreads by blood.

    Improvement during a 6-week treatment with antibiotics

    Top Symptoms:
    spontaneous shoulder pain, moderate fever, painful surgical site
    Symptoms that always occur with chronic upper arm bone infection (osteomyelitis):
    spontaneous shoulder pain
    Hospital emergency room

Swelling of One Arm Treatments and Relief

The treatments for arm swelling vary since there are many different causes. Treatment can also be targeted to the pain that often goes along with swelling. The first step is a knowledge of risk factors and prevention of certain conditions associated with arm swelling.


There are methods of preventing swelling of one arm that can be coordinated between you and your medical provider.

  • Biopsy for cancer: Starting with a biopsy rather than lymph node removal for breast cancer staging and treatment leads to lower rates of arm lymphedema [10].
  • Avoid injected drug use: This behavior is a risk factor for clots and infections. If you do inject drugs, use clean needles and inject intravenously rather than into the skin or muscle, which will decrease the risk of infection.
  • Reduce clot risk: If you have any history of clots, avoid drugs containing estrogen, which will increase the risk of recurrent clots. Avoid smoking, which also contributes to clot risk.

At-home treatments

Some treatment methods for swelling of one arm can begin at home.

  • Pain medication: Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen are effective in treating pain associated with venous compression, injuries, and chronic pain syndrome.
  • Antihistamines: Benadryl, for example, will help alleviate the swelling and itching associated with insect bite reactions.
  • Rest and ice: Initial rest and icing followed by strengthening activities can help with overuse tendinitis[11].

Professional treatments

Professional medical treatments, such as the following, can be recommended after a proper consult with your physician.

  • Anticoagulation medication: This medication inhibits clot formation, and is the best treatment for an arm clot. In some cases, a thrombolytic (medication to break up a clot already present) may also be used [2].
  • Surgery: This may be required to repair anatomic abnormalities causing venous compression [12] or for tendon overuse injuries [11] when other treatments have failed.
  • Antibiotics or drainage: An infection will require antibiotics and possibly drainage of infected fluid.
  • Massage and compression: Blocked lymphatic drainage can be partially improved via massage and compression, as well as addressing underlying causes like an infection or tumor [4].
  • Other medications: Steroids and multiple types of pain medications, including antidepressants and antiepileptic drugs used for nerve pain, can help mitigate chronic pain syndromes[9].

Seek immediate treatment for the following

You should get emergency care if you have:

  • Fever, drainage of a wound, and a spreading red or black/blue color of the skin.
  • Shortness of breath and chest pain, which may indicate that a clot has dislodged from the arm and entered a lung (pulmonary embolism or PE).
  • Extreme pain and blue discoloration of the arm, which may indicate venous backup so severe that arterial blood flow is also blocked [1,2].

FAQs About Swelling of One Arm

Here are some frequently asked questions about swelling of one arm.

Can a swollen arm be a sign of infection?

Yes, a swollen arm may indicate that an infection is present. Redness, warmth, and drainage may also occur. Some types of infection will cause blackened skin. Animal bites, intravenous drug use, and other types of injuries that break the skin are risk factors for infection. Seek emergency care if you have rapidly spreading skin changes or signs of systemic illness such as fever [13,14].

Why does one of my arms swell after activity?

Swelling after activity, particularly a repetitive activity like throwing, can be a sign of venous compression by an anatomic abnormality such as an extra rib. You may also notice pain and/or a red or blue appearance of the arm. It is important to get a medical evaluation if you notice swelling and other changes in your arm after activity since a clot can occur as a complication of venous compression [1-3,12,15].

Why do I have swelling of just one arm?

Many systemic medical conditions can cause swelling of both arms and/or legs; swelling of just one arm indicates a problem on that side. The swelling may be due to infection, particularly if it is localized to one area. It can also be caused by an acute or chronic injury. In addition, a unilateral structural abnormality can cause swelling by obstructing drainage of fluid out of the arm, either in the veins or in the lymphatic system [1,4,13,15].

What treatments are available for a chronically swollen arm?

Arm swelling that persists over time is often caused by a problem with venous or lymphatic drainage. Compression can help reduce swelling in both of these conditions. Additional treatments like massage and particular limb exercises can also be effective for lymphatic blockage. Surgery can be required for chronic swelling, but other treatments are typically tried first [4,12,16].

How can I tell if an insect bite on my arm is infected?

An insect bite is often followed by a small amount of swelling along with itching and redness. Some people develop more extensive reactions at the site of the bite, with a larger area of swelling, redness, and warmth. These large reactions can appear similar to a skin infection. However, the large inflammatory response to a bite starts quickly and peaks in about half a day. If the bite is complicated by an infection, worsening symptoms will occur after a few days [17].

Questions Your Doctor May Ask About Swelling of One Arm

  • Q.Did you just suffer from a high impact injury (e.g., a fall, collision, accident or sports trauma)?
  • Q.Any fever today or during the last week?
  • Q.Does your calf feel very tense?
  • Q.Have you suffered from a burn?

If you've answered yes to one or more of these questions, try our swelling of one arm symptom checker to find out more.

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Swelling of One Arm Symptom Checker Statistics

  • People who have experienced swelling of one arm have also experienced:

    • 11% Pain in One Arm
    • 7% Pain in the Upper Arm
    • 6% Pain in One Shoulder
  • People who have experienced swelling of one arm had symptoms persist for:

    • 32% Less Than a Week
    • 26% Less Than a Day
    • 25% Over a Month
  • People who have experienced swelling of one arm were most often matched with:

    • 54% Deep Vein Thrombosis
    • 36% Cellulitis
    • 9% Repetitive Strain Injury of the Upper Arm
  • Source: Aggregated and anonymized results from visits to the Buoy AI health assistant (check it out by clicking on “Take Quiz”).

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  1. Douketis JD. Deep Vein Thrombosis (DVT). Merck Manual Consumer Version. Updated March 2018. Merck Manual Consumer Version Link
  2. Mintz A, Levy MS. Upper Extremity Deep Vein Thrombosis. American College of Cardiology. Published November 16, 2017. ACC Link
  3. Goshima K. Overview of Thoracic Outlet Syndromes. UpToDate. Updated January 5, 2018. UpToDate Link
  4. Douketis JD. Lymphedema. Merck Manual Professional Version. Updated September 2017. Merck Manual Professional Version Link
  5. Zakaria S, Johnson R, Pockaj BA, Degnim AC. Breast Cancer Presenting As Unilateral Arm Edema. Journal of General Internal Medicine. 2007;22(5):675-676. NCBI Link
  6. Mehrara B. Clinical Features and Diagnosis of Peripheral Lymphedema. UpToDate. Updated February 21, 2018. UpToDate Link
  7. Rennels MB, Deloria MA, Pichichero ME, et al. Extensive Swelling After Booster Doses of Acellular Pertussis Tetanus-Diphtheria Vaccines. Pediatrics. 2000;105(1):online. Pediatrics Link
  8. Golden DBK. Stinging Insect Allergy. American Family Physician. 2003;67(12):2541-2546. AAFP Link
  9. Complex Regional Pain Syndrome Fact Sheet. National Institute of Neurological Disorders and Stroke. Updated July 6, 2018. NINDS Link
  10. Purushotham AD, Upponi S, Klevesath MB, et al. Morbidity After Sentinel Lymph Node Biopsy in Primary Breast Cancer: Results From a Randomized Controlled Trial. Journal of Clinical Oncology. 2005;23(19):4312-4321. ASOC Journal Link
  11. Wilson JJ, Best TM. Common Overuse Tendon Problems: A Review and Recommendations for Treatment. American Family Physician. 2005;72(5):811-818. AAFP Link
  12. Rubin M. Thoracic Outlet Compression Syndromes (TOS). Merck Manual Professional Version. Updated July 2018. Merck Manual Professional Version Link
  13. Spelman D, Baddour LM. Cellulitis and Skin Abscess: Clinical Manifestations and Diagnosis. UpToDate. Updated August 14, 2018. UpToDate Link
  14. Cellulitis. Johns Hopkins Medicine. Johns Hopkins Medicine Link
  15. Young C. Throwing Injuries of the Upper Extremity: Clinical Presentation and Diagnostic Approach. UpToDate. Updated April 18, 2018. UpToDate Link
  16. Douketis JD. Chronic Venous Insufficiency and Postphlebitic Syndrome. Merck Manual Professional Version. Updated March 2018. Merck Manual Professional Version Link
  17. Kelso JM. Large Local Reactions to Mosquito Bites. UpToDate. Updated August 29, 2017. UpToDate Link
  18. Schutzman S. Evaluation of the Immobile Arm in Children. UpToDate. Updated February 12, 2018. UpToDate Link
  19. Berube C, Zehnder JL. Catheter-Related Upper Extremity Venous Thrombosis. UpToDate. Updated September 27, 2018. UpToDate Link
  20. Trayes KP, Studdiford JS, Pickle S, Tully AS. Edema: Diagnosis and Management. American Family Physician. 2013;88(2):102-110. AAFP Link