What Is Phlebitis?

Painful Inflammation of Superficial Veins of the Leg

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Phlebitis is the inflammation of a superficial vein in the leg. It is recognized by the gradual onset of redness, swelling, pain, and a cord-like hardening along the length of the affected vein.

Phlebitis is most often triggered by direct trauma to a vein, resulting in the formation of a blood clot. One of the most common causes is the placement of an intravenous (IV) catheter into a vein of a leg. When a blood clot is involved, it is more accurately referred to as superficial venous thrombophlebitis (SVT).

Other triggers of phlebitis include autoimmune diseases (in which the immune system mistakenly attacks the body's own tissues), blood clotting disorders, and cancer.

This article describes the signs and symptoms of phlebitis and the possible causes and triggers. It also explains how phlebitis is diagnosed and treated based on the underlying cause.

Back of legs of a person with phlebitis

Suze777 / Getty Images

What Are the Warning Signs of Phlebitis?

Phlebitis affects superficial veins, meaning those situated near the surface of the skin that are often visible and wispy. This differs from a more serious condition known as deep vein thrombosis (DVT) which affects deeper veins of the leg.

With phlebitis, the vein becomes inflamed either because the walls of the vein are damaged, a blood clot develops within the vein, or both. People with varicose veins are at greater risk than those without.

Symptoms of phlebitis tend to develop progressively, causing:

  • Localized redness, tenderness, and itchiness along a superficial vein
  • The gradual cord-like hardening of the vein
  • Increasing warmth, swelling, and pain
  • A throbbing or burning sensation

The pain will often get worse when lowering the leg or getting out of bed in the morning. There may also be fever and a pus-like discharge if an infection is involved.

Where Phlebitis Commonly Occurs

Between 60% and 80% of cases of phlebitis occur along the great saphenous vein (GSV), which runs from the inner thigh to the inner foot. Between 10% and 20% of cases occur along the short saphenous vein (SSV), which runs along the back of the leg from just above the knee to the outside of the foot.

Depending on the cause of phlebitis, it can take anywhere from weeks to months for the symptoms to fully subside.

Complications

SVT and DVT are closely linked. Both are caused by the formation of blood clots, and both are subject to recurrence. Adding to these concerns is the fact that SVT can sometimes be an early warning sign of DVT, particularly when it is recurrent.

Different studies have found between 3.1% and 65.6% of people with SVT also had deep venous thrombosis at the same time.

Risk factors include:

  • Venous insufficiency (improperly functioning vein valves in the legs)
  • SVT in a non-varicose vein
  • A prior history of cancer

Female gender was associated with a lower risk for SVT developing into DVT.

Note that Verywell Health prefers to use inclusive terms. But when citing a health authority or study, the terms for gender or sex from that source will be used.

Causes and Risk Factors

Phlebitis, most specifically SVT, is commonly experienced in people with varicose veins. These are large, twisted veins in the legs and feet that are generally more of a cosmetic concern than a medical one. The narrowing and coiling of these veins make them vulnerable to obstruction by blood clots.

With that said, phlebitis can affect people without varicose veins. One of the most common triggers of phlebitis is the placement of a peripheral intravenous catheter (PIVC). Other possible causes include thrombophilia (a blood clotting disorder), autoimmune connective tissue diseases, and cancer.

SVT is seen more often in these groups:

  • Older age (average age 60)
  • Women
  • People with higher body weight
  • People with a history of varicose veins

Peripheral Intravenous Catheter (PIVC)

A PIVC is a type of tubing placed in the vein of an arm or leg that is used to deliver fluids, drugs, or blood transfusions. The placement of a PIVC damages the walls of the vein and triggers an inflammatory response in which blood cells called platelets are activated.

Platelets, also known as thrombocytes, are responsible for blood clotting. During a venous injury, the activation of these cells can cause the formation of clots that can block superficial veins, leading to SVT.

Risk of Phlebitis From IV Catheters

Roughly one in eight people who receive a PIVC will develop phlebitis, according to a 2021 study in the Journal of Intensive Care.

While PIVCs are most commonly used in people in the hospital, SVT tends to be more common in people given a PIVC in an emergency or outpatient setting.

Thrombophilia

Thrombophilia, also known as hypercoagulation, is another possible cause of SVT. The condition is either due to the lack of proteins that regulate blood clotting or to the overproduction of clotting factors that promote clotting.

Causes of thrombophilia include:

  • Antiphospholipid syndrome (an autoimmune form of the disorder)
  • Hereditary thrombophilia (an inherited genetic form of the disorder)
  • Chronic infections like human immunodeficiency virus (HIV), viral hepatitis, and liver disease

Autoimmune Diseases

Autoimmune diseases are those in which the body's immune system mistakenly attacks its own cells and tissues. In cases of SVT, connective tissues that make up blood vessels are the target of the assault.

Autoimmune diseases associated with SVT are characterized by both hypercoagulation and vasculitis (blood vessel inflammation).

The autoimmune diseases commonly linked to SVT include:

Cancer

Active cancer increases the risk of phlebitis, which in some cases may be an early warning sign of malignancy. Phlebitis can occur with any number of cancers, the most common of which include:

  • Brain cancer
  • Colon cancer
  • Lymphoma (cancer of the lymphatic system)
  • Multiple myeloma (a type of blood cancer)
  • Pancreatic cancer
  • Ovarian cancer

Cancerous tumors cause phlebitis by releasing chemicals that stimulate the production of clotting factors. Clotting factors are proteins made by the liver that combine with platelets to form blood clots.

The higher your cancer stage (a measure of how far it has spread, from 0 to 4), the greater your risk of phlebitis.

In severe cases, an active malignancy can trigger the onset of DVT and a potentially life-threatening condition called pulmonary embolism (in which a fragment of a blood clot breaks off and gets lodged in the lungs).

Chemotherapy-Induced Phlebitis

Certain chemotherapy drugs like anthracyclines and Navelbine (vinorelbine) are also associated with an increased risk of SVT (referred to as chemotherapy-induced phlebitis).

How Phlebitis Is Diagnosed

Phlebitis can often be diagnosed with a physical exam and a medical history review. This is especially true in people with varicose veins or those who have undergone a recent PIVC insertion.

Given the increased risk of DVT, your healthcare provider will likely order an ultrasound. In an ultrasound, a handheld device uses sound waves to create detailed images of blood vessels and other soft tissues. This imaging study can help rule out DVT or diagnose borderline cases in which a blood clot is situated closer to a larger vein.

If phlebitis occurs with respiratory symptoms (such as shortness of breath, chest pain, and fainting), a radioactive imaging test called lung scintigraphy may be used to check for a pulmonary embolism.

Other tests may be ordered if SVT is unexplained, recurrent, and/or develops in the absence of varicose veins. These may include blood tests to detect thrombophilia, autoimmune diseases like lupus, or antiphospholipid syndrome. Cancer screening may also be advised based on your family history and individual risk factors.

Cancer screening and blood testing are generally considered unnecessary when SVT develops in the presence of varicose veins.

Treatment of Phlebitis

As painful and distressing as phlebitis can sometimes be, most cases are not serious and will resolve on their own over time.

Uncomplicated cases will typically respond to the following treatments aimed at easing pain and reducing local inflammation:

  • Heat applications: Applying a heating pad or a hot water bottle to the affected area increases blood circulation and promotes healing.
  • Elevating the leg: Propping up your feet as much as possible reduces blood pressure around the affected vein, easing pain and swelling.
  • Compression stockings: Elastic compression socks, available over the counter or by prescription, prevent blood pooling in the lower limbs, reducing pain and swelling.
  • Oral painkillers: Over-the-counter (OTC) nonsteroidal anti-inflammatory drugs (NSAIDs) like Advil (ibuprofen) and Aleve (naproxen) can also reduce inflammation and pain.

Additional treatments may be prescribed based on the severity of your symptoms and/or the location of the venous blockage, including:

  • Anticoagulants: Also known as blood thinners, these may be used in people with varicose veins or those without varicose veins who have SVT in their thighs. Options include Arixtra (fondaparinux) and Lovenox (enoxaparin).
  • Antibiotics: These prescription drugs may be used if there are signs of bacterial infection, such as fever and a pus-like discharge at the PIVC placement site.
  • Hirudoid (heparinoid) cream: This prescription topical cream is commonly used to treat severe bruises caused by ruptured veins (known as hematomas).
  • Surgery: Venous ligation and stripping is a surgical procedure in which the affected vein is tied off and removed through a small incision. It is commonly used to treat varicose veins.

Summary

Phlebitis is the inflammation of a superficial vein of the leg caused by an injury to the vein and/or the formation of a blood clot in the vein. The term superficial venous thrombophlebitis (SVT) is used when a blood clot is involved.

A peripheral intravenous catheter (PIVC) is the most common cause of phlebitis, although phlebitis can also result from an autoimmune disease, thrombophilia, or cancer.

Phlebitis is commonly diagnosed with a physical exam, a medical history review, an ultrasound, and possibly blood tests. The first-line treatment choices are heating pads, compression socks, and OTC anti-inflammatory drugs.

A Word From Verywell

Although many cases of phlebitis are not serious and will resolve on their own without treatment, you shouldn't ignore the symptoms. This is especially true if you've had phlebitis in the past.

According to a 2016 study published in the journal Blood, recurrent phlebitis increases the lifetime risk of DVT and pulmonary embolism by no less than 400%.

By getting a proper diagnosis and treatment, you can take steps to further reduce your risk of DVT, including losing weight, exercising regularly, and quitting cigarettes.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By James Myhre & Dennis Sifris, MD
Dennis Sifris, MD, is an HIV specialist and Medical Director of LifeSense Disease Management. James Myhre is an American journalist and HIV educator.