Phlebitis means "inflammation of a vein".

The vein becomes inflamed because there's blood clotting inside it or the vein walls are damaged.

Superficial thrombophlebitis is the term for an inflamed vein near the surface of the skin (usually a varicose vein) caused by a blood clot.

What are the symptoms?

Symptoms of superficial thrombophlebitis include:

• painful hard lumps underneath the skin
• redness of the skin

This is usually on the lower leg, although it can occasionally affect surface veins in the arms, penis or breast.

Is it serious?

Superficial thrombophlebitis in a leg is not usually serious.

The blood clot usually clears and the inflammation dies down within a few weeks.

Most people with superficial thrombophlebitis are otherwise well.

There should not be any foul discharge or abscess, and it's normally just lumps under the skin rather than swelling of the whole calf.

This may be painful, but it should not prevent you walking normally.

Who's most at risk?

You're more at risk of superficial thrombophlebitis if you:

• have varicose veins
• smoke
• are very overweight
• take the contraceptive pill or HRT (although these only slightly increase your risk of blood clots)
• are pregnant
• have had a previous blood clot or another problem with the vein
• have recently had injections or a drip put into the vein
• have a condition that causes the blood to clot more easily, such as thrombophilia, inflammation of the smaller arteries (polyarteritis) or a high concentration of red blood cells in your blood (polycythaemia)
• have cancer

How is it treated?

Phlebitis is inflammation, not infection, so antibiotics are not helpful.

You can follow this advice to help reduce any pain and swelling:

• raise the leg to help reduce swelling
• ask your doctor if compression stockings would be suitable for you to help reduce swelling
• keep active to keep the blood circulating
• press a cold flannel over the vein to ease any pain
• take anti-inflammatory painkillers, such as ibuprofen
• rub an anti-inflammatory cream or gel on the area if the affected area is only small

What's the outlook?

When the inflammation settles, you may be left with darkened skin and the lump may take 3 or 4 months to go. But most people make a full recovery.

If the thrombophlebitis was in a varicose vein, it's likely that the varicose veins will keep coming back, possibly with further episodes of thrombophlebitis. 

This is because there's a basic problem with the vein and you may need this removed. 

Find out more about how varicose veins are treated

Risk of deep vein thrombosis

There's a small chance of the blood clot travelling along the vein to where it meets a deeper vein and a deep vein thrombosis (DVT) developing.

This is more likely if the surface clot extends into the upper thigh or groin, or behind the knee (in places where superficial veins meet deeper veins).

It's also more likely to happen if:

• the affected vein is a normal vein rather than a varicose vein
• you have had a DVT before
• you're immobile

A DVT can cause pain, swelling and a heavy ache in your leg. See a GP immediately if you experience these symptoms.

Find out more about DVTs