What is Superficial Thrombophlebitis?

Recently a doctor sent a patient with Superficial Vein Thrombosis to see me. It triggered a thought, not many people know about this condition. Superficial thrombophlebitis is inflammation of a vein just under the skin, usually in the leg. A small blood clot also commonly forms in the vein, but is typically not serious. The condition usually settles and goes within 2-6 weeks. Treatments can ease pain or discomfort.

Superficial thrombophlebitis is different to, and much less serious than, deep vein thrombosis (DVT). However, in a small number of cases, complications can occur, including extension of the blood clot further up the vein. In many cases, it can occur for no apparent reason.

Risk factors

There are a number of risk factors that make it more likely for inflammation to develop in a vein:

  • Varicose veins – people who have varicose veins of the legs, particularly pregnant women. These veins are prone to minor injuries which can lead to inflammation.
  • Intravenous injection – sometimes it occurs after having injections into the veins (intravenous injections), or ‘drips’ (intravenous infusions) in hospital. These are commonly given in hand or arm veins. Such procedures can injure the vein and may trigger inflammation.
  • Previous problems with veins – if someone has had a previous case, or DVT, they are more likely to get superficial thrombophlebitis.
  • Abnormalities of blood clotting factors – various conditions can alter certain chemicals (clotting factors) in the bloodstream, which make the blood clot more easily. These include using oral contraceptive pills, hormone replacement therapy, cancer, smoking and pregnancy. There are also some less common hereditary blood disorders where blood clots develop more readily than usual.
  • Blood flowing more slowly than normal – this might occur in veins that are varicose, during long flights, or in people who are immobile, and also following major surgery.

Swelling, redness, and tenderness along a part of the vein are the usual symptoms; you may also develop a high temperature. If a blood clot develops inside the inflamed part of the vein, the area  may then feel hard or knobbly. The blood clot is usually of little concern, as it is small. There are other veins which carry the blood and bypass the blocked vein. When the inflammation settles, a persistent darker area of skin (hyperpigmentation), may remain over the affected vein. A small firm lump may also persist below the skin. This may be tender to the touch for some time.


Most bouts of superficial thrombophlebitis last 3-4 weeks. If they are associated with varicose veins, they are likely to recur. No treatment may be needed if the symptoms are mild. One or more of the following treatments may be advised, depending on your symptoms and the severity of the condition:

  • Keep active. Try to maintain your normal activities. This should be possible unless the pain is severe.
  • Use a hot cloth or heat pad over the vein; this may ease the pain.
  • Painkilling tablets. Check with your doctor or pharmacist. There is also some evidence that anti-inflammatory tablets may reduce the risk of superficial thrombophlebitis enlarging or extending within a vein, and/or it returning. However, more studies are needed to confirm this.
  • Raising the affected leg. When you rest, if you raise an affected leg so that your foot is higher than your hip, it helps to reduce swelling and discomfort. You can do this by lying on a sofa and putting the leg up on some cushions. When sleeping in bed, you can keep your leg raised by putting it on a pillow.
  • Compression (support) stockings. These may be advised by your doctor if a vein in your leg is affected. They may ease discomfort and reduce swelling while the inflammation settles.
Are there any complications?

The inflammation and pain usually settle within a few weeks. Most people make a full recovery. The possible complications listed below are uncommon, but give guidance on what to expect. See a doctor as soon as possible if you suspect that a complication is developing.


Sometimes the affected vein becomes infected. The pain may then become worse and the redness spreads. You are likely to generally feel unwell, and antibiotics are needed to treat the infection. If the infection is severe, you may need to be admitted to hospital for intravenous antibiotics.

Blood clot extension

In some cases, the blood clot can extend further up the vein. If the clot extends to where the superficial and deep veins join, a DVT can develop. This is more likely if the superficial thrombophlebitis is in the upper thigh or the groin, near to where the superficial veins and the deep veins of the leg meet. There is a similar meeting point of superficial and deep veins at the crease behind the knee. It is also more likely to occur if:

  • The superficial thrombophlebitis develops in a previously normal vein (not a varicose vein).
  • You have had a DVT before.
  • You are immobile for some reason.

See a doctor urgently if:

  • Inflammation, redness, or hardness spreads up your inner thigh towards your groin, or is around the back of your knee or calf.
  • Your whole leg swells.
  • Pain suddenly worsens.
  • You develop any new breathing problems, or chest pains. Sometimes a clot from a DVT breaks off and travels to the lung.

When a DVT leads to thrombophlebitis, there is an increased risk of developing further DVTs, and possibly clots on the lung (pulmonary embolism).

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