Thrombophlebitis means inflammation of a vein associated with a blood clot. It most often affects a superficial vein in the leg, called superficial thrombophlebitis or superficial venous thrombosis.

It often improves within 1 to 2 weeks, but it needs medical assessment because a clot can occasionally extend into deeper veins, causing deep-vein thrombosis (DVT). The NHS overview of phlebitis describes these symptoms and advises evaluation to rule out DVT.

Seek urgent care now if there is:

Treatment depends on site, clot length, and risk factors. It may include walking as tolerated, warm compresses, anti-inflammatory pain relief if safe for you, compression when advised, and sometimes anticoagulant medication. An ultrasound may be needed to check for DVT. Do not start blood-thinning medicines without a clinician’s advice.

If you mean you have these symptoms, tell me where the pain/swelling is, how long it has been present, and whether you have chest symptoms or one-sided leg swelling.