Phlebitis / Superficial Thrombophlebitis
What is phlebitis?
Phlebitis means inflammation of a vein close to the surface of the skin. It is also known as superficial thrombophlebitisor superficial vein thrombosis (SVT).
It most commonly affects the veins of the legs and is frequently associated with varicose veins.
The affected vein can become inflamed and may contain a small blood clot. Although superficial phlebitis is usually less serious than a deep vein thrombosis (DVT), the symptoms can sometimes be similar, so new or unexplained symptoms should not be ignored.
What does it look and feel like?
Symptoms can develop over several hours or a few days.
You may notice:
Pain or tenderness along a vein
Localised swelling
Warmth over the affected area
Red, purple or darker discolouration of the skin
Itching or irritation
A vein that feels hard, thickened or cord-like beneath the skin
Tender varicose veins
Redness may be less obvious on brown or black skin, so changes in warmth, tenderness, swelling and skin texture are also important.
Why does phlebitis happen?
Blood normally travels back towards the heart through the veins of the legs. Small valves within the veins help prevent blood flowing backwards.
When these valves become less effective — as commonly happens with varicose veins — blood can pool within the vein. This slower blood flow can contribute to inflammation and clot formation.
Phlebitis may also occur following irritation or injury to a vein, such as after an injection or intravenous cannula.
Who is more at risk?
Phlebitis can happen to anyone, but the likelihood is increased by factors including:
Varicose veins
Previous phlebitis or blood clots
Increasing age
Pregnancy
Obesity
Smoking
Cancer
Conditions that make the blood more likely to clot, such as thrombophilia
Some hormone treatments, including HRT
Injections or a cannula placed into a vein
Not everybody who develops phlebitis will have an obvious risk factor.
Is phlebitis the same as a DVT?
No.
Phlebitis affects a vein near the surface of the skin, whereas a deep vein thrombosis (DVT) is a blood clot within one of the deeper veins.
However, some of the symptoms overlap and, in some circumstances, superficial vein thrombosis can extend towards the deeper venous system. This is why suspected phlebitis should not simply be assumed to be harmless without appropriate assessment.
When should I seek medical advice?
Seek an urgent GP appointment or contact NHS 111 if you develop:
New throbbing or cramping pain in a leg
Sudden swelling of a leg
Warmth around a painful area
Red or noticeably darker skin around the area
A swollen vein that feels hard or painful
Symptoms which are rapidly worsening or spreading
These symptoms may need assessment to exclude a DVT.
Call 999 immediately if you develop:
Sudden or unexplained shortness of breath
Chest pain, particularly pain that worsens when breathing in
Coughing up blood
Sudden collapse or severe light-headedness
These can be symptoms of a pulmonary embolism (PE) and require emergency medical attention.
How is phlebitis treated?
Mild superficial phlebitis often improves naturally and may settle within around 1–2 weeks.
Depending upon the severity and location of the clot, treatment may include:
Keeping mobile and continuing to use the affected limb
Elevating the limb when resting
Applying a warm, moist compress
Paracetamol or an anti-inflammatory medicine where appropriate
Compression hosiery in selected patients
Anticoagulant (“blood-thinning”) medication where there is a greater risk of the clot extending or further clots developing
Compression hosiery should be recommended and fitted by an appropriately qualified healthcare professional rather than purchased simply because phlebitis is suspected. If you already take anticoagulant medication, speak to your GP or pharmacist before taking ibuprofen or another NSAID.
What happens afterwards?
Pain and inflammation usually gradually improve. The vein itself may remain firm or lumpy for some time, and temporary darker pigmentation of the skin may remain after the inflammation has settled.
If phlebitis repeatedly develops within varicose veins, the underlying venous problem may need further investigation and treatment.