This page is a guide to foam sclerotherapy injection treatment for varicose veins and should answer some of the questions you may have. Please note that this page is not a complete list of all information about varicose veins.

What are varicose veins?

There are 2 types of veins in the legs; deep veins and superficial veins. The deep veins run within the muscles of the leg and the superficial veins run just below the surface of the skin. Within the veins are small one-way valves which allow blood to flow upwards towards the heart. When these valves no longer work, blood is allowed to flow backwards down the vein which, in turn, causes high pressure within the veins. This high pressure leads to the veins becoming enlarged which can be seen visibly as bulges beneath the skin.

Varicose veins can cause aching, swelling, itching discomfort and heaviness in the legs. In some people the skin becomes discoloured which can lead to ulceration.

What can be treated?

Foam sclerotherapy can be used to manage varicose veins which would otherwise need surgical treatment.

What cannot be treated?

Very large, extensive varicose veins are best treated by surgery.

Small varicose veins and thread veins are best treated by microsclerotherapy which is not available on the NHS.


Before treatment, please tell your clinician about the medication you are currently taking.

Foam sclerotherapy is usually performed in the vascular treatment room or outpatient department. Sometimes the procedure is carried out with or without local anaesthetic depending on your choice. The aim is to inject and destroy the veins that are not working properly.

The procedure is carried out while you are lying down. A needle is placed within the affected vein. Ultrasound imaging is used to help guide the needle(s) to the correct position. Often 2 to 3 needles are inserted to treat all the veins in one leg. The leg being treated is then raised to shrink the varicose veins. The foam is then prepared and injected into the vein. The foam rapidly spreads along the vein and is monitored using the ultrasound.

The foam does not stay in the veins; it simply damages the non-stick lining of the vein and then disperses within the blood stream. Often only 1 session of foam is needed, but sometimes the foam does not reach all of the varicose veins and additional injections are required on another occasion.

After giving you foam injections, we may apply a firm bandage and/or a compression (elastic) stocking to your treated leg.

If you have bandages, these can be removed after

2 days, but an elastic stocking should be worn continuously for a further 7 to 14 days, your clinician will advise you.

Walking or being mobile after the treatment is advised to help prevent deep vein blood clots. The clinician looking after you will give you clear instructions of what to do.

We do not routinely see you following your treatment, if you have any concerns, please ask your GP for advice or contact your consultant’s secretary.

Alternative treatments

  • Surgery which usually requires a general anaesthetic (performed while you are asleep).
  • Compression stockings may improve symptoms but will not remove the varicose veins.
  • Veins can also be treated using radio frequency ablation or laser therapy which may be carried out under local or general anaesthetic.

Risks and complications

Common risks and complications

  • Bruising is common but usually disappears in about 2 weeks.
  • At first the veins often appear lumpy and can still be visible and felt beneath the skin. These will slowly reduce over 3 to 6 months.
  • Often a pale brown colour appears on the skin where large veins have been injected. This will gradually fade over a number of months, but is sometimes permanent.
  • Occasionally, a varicose vein becomes a painful lump following this treatment. This is called ‘thrombophlebitis’ and can be treated by inserting a needle and removing the clot causing the problem from the vein. If you are able to take anti-inflammatory medication such as ibuprofen tablets or gel, this can be used to help reduce the discomfort.
  • Foam sclerotherapy treatment may result in the development of thread veins in the area of treatment for some people.
  • There is no guarantee that this treatment will get rid of all of your varicose veins or cure all of your leg symptoms.

Rarer risks and complications

  • Rarely, thrombosis may spread to the deep veins following injections for varicose veins. This is called Deep Vein Thrombosis (DVT). DVT’s causing symptoms can happen in 1 in every 200 people.
  • Pulmonary Embolus (PE) or a blocked blood vessel in the lungs is very rare.
  • Visual disturbances can happen after the injection but this usually lasts for a few minutes and should have no long-term effects. This may be more common in migraine sufferers.
  • If you suffer from migraines, you may experience an episode immediately after treatment but this should resolve with your normal medication.
  • Ulceration at the injection site can happen but is rare.
  • Rarely a severe allergic reaction to the foam can happen in about 1 in every 50,000 patients.
  • Stroke is extremely rare but has been described in the medical journals.
  • Rarely the treatment may be unsuccessful.

Further sessions

We often treat one leg at a time. Therefore, if varicose veins affect both legs, a further treatment to the other leg is given several weeks later.

Benefits of having foam sclerotherapy treatment

  • Avoids the need for hospital admission, surgery and general anaesthesia.
  • Only minor discomfort during the treatment and minimal bruising compared to surgery.
  • All treatment is performed as an outpatient and little time is needed off work.

Disadvantages of foam sclerotherapy

  • More clinic attendances required than for surgical treatment (usually several appointments if both legs are treated).
  • Sometimes it takes several months for the lumpiness and bruising to resolve.
  • May not be as long lasting as other forms of varicose vein treatment, the veins treated can re-open or recur.
  • Treatment may produce thread veins in some people (these may also appear following surgical treatment for varicose veins).

Activity and returning to work

You are advised to be mobile soon after your treatment, returning to normal activities as quickly as possible. You can return to work the next day. We do not give you a medical certificate as this is not generally necessary. You are advised not to travel by air for 4 to 6 weeks following foam sclerotherapy treatment.


It is not advisable to drive on the day of your injections. You should be able to drive the following day as long as you are not restricted by the bandages and/or stocking.

You should be able to perform an emergency stop comfortably and without hesitation.

If you require further information, please contact the doctor or nurse looking after you.

Contact information

Please contact your consultant’s secretary if you have any questions or concerns.

If your concern is urgent, please contact your GP or NHS 111 for advice.

NHS 111

Tel: 111

Further information

National Institute for Health and Care Excellence (NICE)


NHS - Varicose vein treatment

Printable version of this page

Foam sclerotherapy for varicose veins GHPI0993_01_23.docx Department: Vascular Review due: January 2026 PDF, 166.9 KB, 5 pages
Reference number GHPI0993_01_23
Department Vascular
Review due January 2026