A short story: what would you do?
Follow Aling Fe to learn the warning signs and what to do. Turn on your sound for the narration.
What happens
Your legs have two sets of veins. Superficial veins run just under the skin; varicose veins are superficial veins that have become wide and twisted. Deep veins run inside the muscles. [Ref: JAMA 2025 Superficial Vein Thrombosis]
When blood moves slowly in a superficial vein, or the vein wall is irritated, a clot can form and the vein becomes inflamed. In the arm, this often follows an IV line. Doctors also call it superficial thrombophlebitis. [Ref: JAMA 2025 Superficial Vein Thrombosis] [Ref: Thrombosis Canada 2023 Superficial Vein Thrombosis]
Superficial vein clotSuperficial vein thrombosis. A hard, red, painful cord under the skin. It needs a check-up and an ultrasound.
Deep vein clotDeep vein thrombosis (DVT). Often a swollen, painful leg. It can travel to the lungs. About DVT and PE
How common is it?
In studies, about 64 to 131 of every 100,000 people get superficial vein thrombosis each year. It is more common in women. [Data: JAMA 2025 Superficial Vein Thrombosis]
Signs
A hard, tender cordA vein under the skin feels firm like a cord and hurts when touched.
Redness and warmthAlong the path of the vein.
Often in varicose veinsMost leg cases start in veins that were already varicose.
Not always harmless
About 1 in 4 people with a clot in a superficial vein of the leg also have a clot in a deep vein (DVT) when they are checked, and about 4 in 100 have a clot in the lungs. The clot can also grow into the deep veins. [Ref: JAMA 2025 Superficial Vein Thrombosis] [Ref: Thrombosis Canada 2023 Superficial Vein Thrombosis]
See a doctor soon for an ultrasound
See a doctor the same day if the hard, red vein is in your thigh, near your groin or behind your knee, or if your whole leg swells. Go to the emergency room now if you also have sudden shortness of breath or chest pain. [Ref: ESVS 2021 Venous Thrombosis] [Ref: Thrombosis Canada 2023 Superficial Vein Thrombosis]
Who is at risk
- Varicose veins. Up to 8 in 10 people with superficial vein thrombosis have them. [Ref: Thrombosis Canada 2023 Superficial Vein Thrombosis]
- Older age, being overweight, and long periods of not moving. [Ref: JAMA 2025 Superficial Vein Thrombosis] [Ref: Thrombosis Canada 2023 Superficial Vein Thrombosis]
- Pregnancy and the weeks after giving birth, and hormone treatments such as some birth control pills or hormone replacement. [Ref: JAMA 2025 Superficial Vein Thrombosis] [Ref: Thrombosis Canada 2023 Superficial Vein Thrombosis]
- Cancer, recent surgery or injury, or a past blood clot. [Ref: JAMA 2025 Superficial Vein Thrombosis] [Ref: Thrombosis Canada 2023 Superficial Vein Thrombosis]
- An IV line in the arm, during or after a hospital stay. [Ref: JAMA 2025 Superficial Vein Thrombosis]
What happens at your check-up
Your doctor will ask about your symptoms and examine the vein and both legs. [Ref: JAMA 2025 Superficial Vein Thrombosis] [Ref: Thrombosis Canada 2023 Superficial Vein Thrombosis]
Leg vein ultrasound
The key test. It shows how long the clot is, how close it is to the deep veins, and whether there is also a DVT. It is painless and uses no radiation. [Ref: ESVS 2021 Venous Thrombosis] [Ref: Thrombosis Canada 2023 Superficial Vein Thrombosis]
Blood tests
A blood test called D-dimer cannot tell on its own whether you have a clot, so an ultrasound is still needed. [Ref: JAMA 2025 Superficial Vein Thrombosis]
A repeat ultrasound
Your doctor may repeat the ultrasound after about a week to check that the clot is not growing. [Ref: Thrombosis Canada 2023 Superficial Vein Thrombosis]
Your doctor decides which tests you need and explains what the results mean for you.
A hard, red, painful vein? Get it checked.
Only an examination and an ultrasound can tell how far the clot reaches and which treatment is right for you. Dr. Aaron Christopher P. Novales sees patients with clots in the leg veins.
Sudden shortness of breath or chest pain? Do not wait for a clinic visit. Go to the emergency room now →
How it is treated
About the medicines on this page
Medicines are described here only to help you understand your doctor's plan. Do not buy or take any medicine because you read about it here. Take only what your doctor prescribes for you, and never start, stop or change a dose on your own.
Treatment based on the ultrasound
A short clot far from the deep veins may only need care to ease the pain and swelling. A longer clot, or one close to the deep veins, is treated with a blood thinner prescribed by your doctor. Your doctor decides which treatment you need and for how long. [Ref: JAMA 2025 Superficial Vein Thrombosis] [Ref: Thrombosis Canada 2023 Superficial Vein Thrombosis]
Keep moving
Walking is usually encouraged. Your doctor may also advise compression stockings, if the arteries in your legs are healthy. [Ref: JAMA 2025 Superficial Vein Thrombosis] [Ref: Thrombosis Canada 2023 Superficial Vein Thrombosis]
Clots from an IV line
These usually settle once the line is removed. Tell your nurse or doctor if the vein stays red, hot or painful, or if you have a fever. [Ref: Thrombosis Canada 2023 Superficial Vein Thrombosis]
Antibiotics are not needed unless there are signs of infection. [Ref: Thrombosis Canada 2023 Superficial Vein Thrombosis]
Talk to your doctor about
Bring these questions to your visit.
- How long is the clot, and how close is it to my deep veins?
- Do I also have a DVT?
- Do I need a blood thinner?
- Should I have another ultrasound?
- Should my varicose veins be treated?
Related conditions
Guideline sources for this page
- JAMA 2025 Superficial Vein Thrombosis: Piazza G, Krishnathasan D, Hamade N, et al. Superficial vein thrombosis: a review. JAMA 2025;334(22):2020–2030.
- Thrombosis Canada 2023 Superficial Vein Thrombosis: Thrombosis Canada. Clinical guide: superficial thrombophlebitis, superficial vein thrombosis. Version 10 August 2023.
- ESVS 2021 Venous Thrombosis: Kakkos SK, et al. ESVS 2021 Clinical Practice Guidelines on the management of venous thrombosis. Eur J Vasc Endovasc Surg 2021;61:9–82.