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Thread Veins

Thread Veins vs Varicose Veins: How to Tell the Difference

People often use the terms thread veins and varicose veins interchangeably  but theyre not the same thing. This guide explains how to tell the difference, when its worth getting checked, and what treatments are available.

The key difference is this: thread veins are small surface vessels (often cosmetic), while varicose veinsare larger veins caused by valve failure (venous reflux) and are more likely to cause symptoms and long-term skin changes.

Quick comparison

Thread veins (spider veins)Varicose veins
SizeVery small (fine red/blue lines)Larger, bulging veins
AppearanceWeb-like clusters, flatRaised, lumpy, twisted
Main causeSurface vessel dilation; sometimes feeder veinsValve failure (venous reflux)
SymptomsOften none; sometimes mild aching/itchingAching, heaviness, swelling, cramps, skin changes
Best testClinical assessment; ultrasound if symptomsDuplex ultrasound is essential
Typical treatmentsMicrosclerotherapy / laser (selected cases)RFA, foam sclerotherapy, avulsions

What do thread veins look like?

Thread veins (also called spider veins or telangiectasia) are small, visible veins close to the skin surface. They often look like fine red, purple or blue lines, sometimes in a spider-web pattern.

Theyre very common and are often treated for cosmetic reasons. However, in some people they occur alongside underlying venous reflux.

What do varicose veins look like?

Varicose veins are larger, bulging veins that develop when the valves inside a vein stop working properly. Blood flows the wrong way (reflux), pressure builds up, and the vein stretches.

They may be obvious on the surface, or they can be hidden deeper under the skin  still causing symptoms.

Symptoms: what should you pay attention to?

If you have visible veins plus any of the symptoms below, its worth getting assessed:

  • Aching or heaviness in the legs (often worse later in the day)
  • Swelling around the ankles
  • Itching, burning or tenderness over veins
  • Night cramps or restless legs
  • Skin changes (eczema-like rash, brown staining, thickening)
  • Bleeding from a vein or a hard, tender lump (phlebitis)

Do you need an ultrasound scan?

A duplex ultrasound is the gold-standard test for venous reflux. You dont always need a scan for purely cosmetic thread veins, but its often recommended if you have symptoms, visible varicose veins, or signs of venous disease.

Treating visible thread veins without addressing underlying reflux can lead to disappointing or short-lived results.

Treatment options (in plain English)

Thread veins

  • Microsclerotherapy: tiny injections to close thread veins so they fade over time.
  • Laser: sometimes used for very fine veins or facial thread veins.

Varicose veins

  • Radiofrequency ablation (RFA): seals the main faulty vein using controlled heat.
  • Foam sclerotherapy: injection treatment to close selected veins.
  • Avulsions (phlebectomy): removes bulging surface veins through tiny incisions.

Helpful next steps

If youre not sure what type of veins you have, start with a specialist assessment. Its the quickest way to get clarity and avoid unnecessary treatment.

Learn more about thread veins

Causes, symptoms, and treatment options including microsclerotherapy.

Thread veins overview 

Learn more about varicose veins

Symptoms, when to seek help, and modern walk-in, walk-out treatments.

Varicose veins overview 

Book your consultation

If youd like clear answers and a personalised plan, request an appointment. Consultations are typically available within five days.

If you have urgent symptoms (e.g. sudden leg swelling or significant bleeding), please seek urgent NHS assessment via 111 or A&E.