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Is Phlebitis Dangerous and Life-Threatening?

“Is Phlebitis Dangerous and Life-threatening''

I will explain why Yes, Phlebitis can be dangerous and life-threatening. I will also cover what it is, what causes it, what it looks like, what you should do if you think you have phlebitis

What is Phlebitis?

Phlebitis is an inflammation of a vein. The vein is hot, red and lumpy. The lump is tubular in shape and it is tender to touch, it may throb and walking may be painful. The cause of phlebitis in the leg is most often a clot in the vein just under the skin. The clot may disperse and the phlebitis then gets better, but sometimes phlebitis is serious and the condition may become dangerous.

What are the risk factors?

When specifically talking about phlebitis in the leg veins, there are certain risk factors that increase the chances of a blood clot forming:
  • Obesity
  • Smoking
  • Pregnancy
  • Immobility for long periods
  • Varicose veins
  • Some oral contraceptives and hormone replacement therapy (HRT)
  • Certain medical conditions (cancer, blood disorders)

What are the signs of Phlebitis?

In the case of leg vein phlebitis, you may not have any symptoms but if you do, they generally tend to be pain, sensitivity, redness and bulging of the vein.

As you can see in this photograph of phlebitis, the skin over the vein is often discoloured but sometimes there may be nothing to see, particularly if the vein is a little deeper under the skin.

This patient had quite a lot of tenderness. 

An ultrasound scan confirmed that there was clot in the vein and I prescribed blood thinning medication.

When is Phlebitis Dangerous?

Phlebitis does not usually result in serious complications. However, if the clot in the superficial vein is extensive and if it involves the area where the superficial vein and a deep vein come together that is near the groin or behind the knee, a DVT can develop.
Sometimes people are unaware that they have a DVT until they experience a life-threatening complication. The most common and serious complication of DVT is a PE. A PE occurs when a piece of the blood clot breaks off and travels to the lungs, where it blocks blood flow.
Symptoms of a PE include:
  • unexplained shortness of breath
  • chest pain
  • coughing up blood
  • pain with deep breathing
  • rapid breathing
  • feeling lightheaded or passing out
  • fast heart rate

What Should I do if I think I have Phlebitis?

If you think you have phlebitis, you should see your GP and request a scan. If the area of redness, lumpiness or tenderness is getting bigger, if it is near your groin or at the back of your knee, then the phlebitis may be near a deep vein. You may be at high risk of a DVT. Request a scan and insist that is done urgently.


  1. Phlebitis is not caused by an infection and antibiotics are not necessary.
  2. Phlebitis most commonly affects the leg veins and it causes swelling, tenderness and redness along the vein. Less common sites include the arm and the chest.
  3. The diagnosis requires a duplex ultrasound scan. Conditions such as cellulitis can mimic phlebitis so confirming the correct diagnosis with a duplex ultrasound scan is essential and it ensures you get the right treatment.
  4. The fundamental problem causing the inflammation in the vein is clot formation which can spread to the deep veins causing a deep vein thrombosis and pulmonary embolism. Many experts suggest that the term phlebitis should be replaced by the term superficial venous thrombosis. This term more accurately describes the potential for DVT.
  5. The duplex ultrasound scan should not only check the area that is painful, but both legs should be examined for a possible deep vein thrombosis. When someone has phlebitis, they can be in a so-called hypercoagulable state in which the blood is sticky. That means that clots can develop elsewhere in the body, including in the deep veins of the other leg as well.