Foam sclerotherapy for varicose veins (Ultrasound-guided foam sclerotherapy)
An injection treatment for varicose veins, where a foamed medicine is injected to irritate the vein lining so the vein collapses and is absorbed by the body.
✓ Medically reviewed by a GMC-registered consultant · last reviewed September 2026 · next review September 2027 · how we review
In short
- Foam sclerotherapy closes varicose veins with an injected foam medicine, avoiding cuts or heat.
- More than one session is often needed, and treated veins can sometimes reopen over time.
- Recovery is usually quick, but brown skin staining and lumpy, tender veins are common for weeks.
- Rare but serious reactions (including effects on vision, and very rarely stroke-like events) mean it should be done by an experienced vascular specialist who explains these risks.
A plain-English summary. The detail — including risks and recovery — is below.
At a glance
A general guide. Your specialist will give you advice for your situation.
Treats varicose veins without cuts and usually without anaesthetic
A heat (endothermal) treatment is suitable, which NICE recommends first for the main trunk vein.
You walk after the injections and go home. Keep moving little and often rather than sitting for long periods.
A follow-up scan to confirm veins have closed and to look for clot problems.
You walk after the injections and go home. Keep moving little and often rather than sitting for long periods.
Wear compression as advised. Aching, bruising and tender, lumpy veins are normal. Most people return to work and...
Lumpy veins gradually soften. Brown staining may appear over the treated veins. Avoid long-haul travel early...
Veins fade and staining usually lightens. A review or scan checks whether the veins have closed and whether a...
What is foam sclerotherapy?
Foam sclerotherapy treats varicose veins by injecting a medicine (a sclerosant) that has been mixed with a little air or gas to make a foam. The foam irritates the inner lining of the vein, making it spasm, collapse and stick together. Over weeks to months the body gradually absorbs the closed vein and blood reroutes through healthy veins.
Varicose veins occur when small valves inside leg veins stop working, so blood pools and the veins bulge. Foam sclerotherapy can treat the underlying faulty vein as well as smaller surface and tributary veins. Ultrasound is usually used to guide the needle and watch the foam fill the vein, which is why it is often called ultrasound-guided foam sclerotherapy.
UK guidance (NICE) recommends foam sclerotherapy when a heat (endothermal) treatment such as radiofrequency ablation or laser is unsuitable. It avoids cuts and is usually done without anaesthetic, but more than one session is often needed and the treated veins can sometimes reopen later.
Foam sclerotherapy is different from microsclerotherapy, which uses a weaker solution for tiny thread (spider) veins and is usually a cosmetic treatment.
Types, options & approaches
There may be different ways to do this. The right approach depends on the clinical question and your circumstances.
Foam injection vs heat ablation vs surgery
| Feature | Foam injection | Heat ablation (RFA/laser) | Surgery |
|---|---|---|---|
| Cuts needed | No | Tiny entry point | Yes |
| Anaesthetic | Usually none | Local | Often general |
| NICE order | If heat unsuitable | First choice | If both unsuitable |
| Repeat sessions | Often | Sometimes | Less often |
NICE recommends these in order of suitability for your veins. A duplex ultrasound scan helps decide which is right.
Preparing for your injection
- Have a duplex ultrasound scan of your leg veins first so the faulty veins are mapped and treatment is appropriate.
- Tell the team about any previous blood clots (DVT), clotting disorders, migraine with aura, or a hole in the heart (patent foramen ovale) if known.
- List all medicines and supplements, including blood thinners, the contraceptive pill and HRT.
- Mention any allergy to sclerosant medicines or previous reaction to injections.
- Bring or arrange compression stockings to wear afterwards as advised.
- Plan to walk after the appointment rather than rest, and wear loose clothing.
- Tell them if you are pregnant or might be, or are breastfeeding.
What happens
Foam sclerotherapy is usually done awake as an outpatient, often without any anaesthetic because only fine needles are used. You lie down and the leg is cleaned. Using ultrasound to guide the needle, the specialist injects the foamed medicine into the faulty vein and watches it fill and close the vein.
Several injections may be made along one or more veins. You may feel a small sting or a mild ache as the foam goes in. After the injections, a compression stocking or bandage is applied and you are usually asked to walk for a period before going home.
The treated veins are not removed; they close and are absorbed by the body over the following weeks to months. Because veins can reopen or only partly close, more than one session is often needed, and a follow-up scan is common.
Is this injection right for me?
A good consultation should explore whether it's the right choice for you now — including reasons to wait or consider something else.
May not be suitable if…
- A heat (endothermal) treatment is suitable, which NICE recommends first for the main trunk vein.
- You have a current deep vein clot, or the deep veins are blocked so superficial veins are aiding blood return.
- You have a known allergy to the sclerosant medicine.
- You are unable to walk or mobilise afterwards, which is part of reducing clot risk.
- You have significant arterial disease in the legs affecting compression and healing.
Delay or rearrange if…
- You are pregnant or breastfeeding — treatment is usually deferred.
- You have an active leg or skin infection.
- You have had a recent blood clot or are acutely unwell.
- Anticoagulation or a clotting disorder needs review and a clear plan.
- You have not yet had a duplex ultrasound scan to map the veins.
Alternatives to discuss
- Radiofrequency or laser ablation, recommended first for suitable trunk veins.
- Surgery (ligation and stripping) if heat and foam are both unsuitable.
- Compression stockings and lifestyle measures for mild symptoms.
- Phlebectomy for bulging surface veins.
- Watchful waiting if symptoms are mild.
Before you decide
Use this as a shared-decision checklist. The aim is not just “can this be done?”, but whether it is right for you, now, with the risks and alternatives clearly understood.
What matters most to me?
Think about symptoms, daily life, work, caring responsibilities, sport, fertility, travel, appearance and anxiety — the right choice depends on your priorities, not just the medical facts.
What are all my options?
Ask about waiting, monitoring, medicines, rehabilitation, a smaller or larger procedure, a different test, NHS referral, or a second opinion where that would help.
What would make me pause?
Active infection, pregnancy, unstable medical problems, smoking, medicines that increase bleeding, poor support at home, or feeling pressured are all reasons to slow down and get tailored advice.
What happens if I do nothing today?
For some problems, waiting is safe; for others, delay can make treatment harder. A good consultation should explain the trade-off in plain English.
Comfort, sedation or contrast choices
If local anaesthetic, sedation, contrast or pain relief is used, ask what is planned, why, and what it means afterwards.
Benefits
- Treats varicose veins without cuts and usually without anaesthetic
- Can ease aching, heaviness, itching and swelling caused by varicose veins
- Can treat veins in awkward positions or below previous treatment
- Quick to perform and usually a fast return to normal activities
- Useful when a heat treatment is unsuitable, or to tidy up remaining veins after ablation
Risks & complications
- Brown or grey skin staining (pigmentation) over the treated veins, which can last months
- Lumpy, firm, tender veins (trapped clotted blood) that settle over weeks
- Bruising and aching along the treated vein
- Veins not fully closing, so further sessions are needed
- Tiny new red thread veins near the treated area (matting)
- Inflammation of the vein (thrombophlebitis) causing redness and soreness
- Temporary visual disturbance, chest tightness, dry cough or headache shortly after injection
- Small skin ulcer or sore if foam leaks outside the vein, occasionally leaving a scar
- Allergic-type reaction to the sclerosant
- Deep vein thrombosis (a clot in a deep leg vein)
- Pulmonary embolism (a clot travelling to the lungs)
- Serious neurological events including stroke or transient ischaemic attack, reported rarely and linked in part to a heart defect (PFO)
- Very rarely, heart-related events or seizures
Most side effects are skin staining and lumpy, tender veins that settle. The rare but serious risks — clots, and effects on the brain or vision that have been reported especially in people with a hole in the heart (PFO) or migraine with aura — are why NICE advises that these be explained during consent and why the treatment should be done by an experienced specialist. Tell them about migraine with aura, a known PFO, or previous clots.
Published figures to discuss
Reported rates vary with vein size, the volume and type of foam, and how complications are recorded. Skin staining and lumpy, tender veins are common but settle. Closure is less durable than heat ablation for trunk veins, so repeat sessions are more often needed. Serious events such as clots and neurological reactions are rare; some neurological events have been linked to a hole in the heart (PFO). Figures below are cautious and should be discussed for your situation.
| Figure | Reported range | How to interpret it | Source / confidence |
|---|---|---|---|
| Skin staining (pigmentation) over treated veins | Around 6% reported at 2-year follow-up in a NICE-reviewed trial (vs about 1% after surgery) | Usually fades over months; sun protection helps. Rates vary by sclerosant and vein. | NICE CG168 — Varicose veins: diagnosis and managementnice.org.ukPublished figure |
| Temporary visual disturbance shortly after injection | Reported in roughly 5 of 977 patients in a NICE-reviewed case series | Usually short-lived; more often discussed in people with migraine or a known PFO. | NICE CG168 — Varicose veins: diagnosis and managementnice.org.ukSource-linked context |
| Headache shortly after injection | Reported in about 3 of 977 patients in a NICE-reviewed case series | Generally settles within a day. | NICE CG168 — Varicose veins: diagnosis and managementnice.org.ukSource-linked context |
| Pulmonary embolism | Very rare — about 1 of 977 patients in a NICE-reviewed case series | Movement and compression reduce clot risk; previous clots raise it. | NICE CG168 — Varicose veins: diagnosis and managementnice.org.ukSource-linked context |
| Serious neurological events (stroke/TIA) | Rare but reported; numbers too small for a reliable percentage | NICE advises these, and rare cardiac events and seizures, be covered during consent; linked in part to PFO. | NICE CG168 — Varicose veins: diagnosis and managementnice.org.ukSource-linked context |
These are literature figures, not a personalised prediction. Your own risks and likely benefits depend on your circumstances, your health, and how your care is carried out and followed up.
What happens afterwards
Recovery is usually quick and most people return to normal activities the same or next day, walking as advised. But the cosmetic result takes time: brown staining and lumpy, tender veins are common for weeks to a few months before veins fade.
- Brown or grey staining along the treated veins
- Firm, tender, lumpy veins that gradually soften over weeks
- Bruising and mild aching in the treated leg
- Some veins still visible, needing one or more further sessions
- Occasional small patches of new thread veins (matting)
Aftercare
- Walk regularly and avoid sitting or standing still for long periods in the first couple of weeks.
- Wear your compression stocking for as long as the team advises.
- Take simple pain relief such as paracetamol if needed.
- Avoid long-haul flights and very long journeys early on unless your specialist says it is safe.
- Protect treated areas from strong sun, which can worsen staining.
- Attend any follow-up scan to check the veins have closed and look for clot problems.
- Know who to contact about calf pain, swelling, breathlessness, or a spreading skin sore.
- Duplex ultrasound scan done before treatment
- Compression stockings ready
- Plan to walk and stay mobile afterwards
- Simple pain relief at home
- Loose clothing and comfortable shoes
- Time set aside for possible further sessions
- Clinic contact number for problems saved
Scars and how they heal
Foam sclerotherapy uses fine needles, so there are no cuts and no surgical scars. Brown or grey skin staining over the treated veins is common and usually fades over months, though it occasionally lingers. If foam leaks outside a vein it can rarely cause a small skin ulcer that may leave a mark.
⚠ Get urgent help if…
- Painful, swollen or hot calf or thigh — this could be a deep vein clot
- Sudden breathlessness or chest pain — call 999, as this could be a clot on the lung
- Sudden weakness, facial droop, speech or vision problems — call 999 (stroke warning signs)
- Spreading redness, increasing pain, pus or fever (signs of infection)
- A skin sore or ulcer developing at an injection site
- Severe or worsening chest tightness, wheeze or feeling faint after injection
Who to contact: your clinician, clinic or test provider first (keep their number to hand). For urgent advice when you can't reach them, call NHS 111. In an emergency, call 999.
General guidance — it doesn't replace the specific advice your specialist gives you.
Results & realistic expectations
A good result means the treated veins close, symptoms such as aching and heaviness improve, and the veins gradually fade over weeks to months. Ultrasound can confirm whether the deeper veins have closed.
Foam sclerotherapy does not always close a vein in one go, and treated veins can reopen, so more than one session is often needed and results are generally less durable than heat ablation for the main trunk veins. New varicose veins can also develop later, because the underlying tendency remains. It is a treatment for the veins you have now, not a guarantee against future veins.
Treated veins can stay closed for years, but reopening (recanalisation) is more common than after heat ablation, particularly for larger trunk veins, so repeat treatment is more frequently needed. New varicose veins can appear over time. Many people accept that occasional top-up sessions may be needed to keep symptoms and appearance under control.
Related tests, treatments or support
Foam sclerotherapy is often combined with radiofrequency or laser ablation — the main vein is sealed by heat and remaining surface or tributary veins are injected with foam. It is not the same as microsclerotherapy for tiny thread veins, which is a separate, usually cosmetic, treatment.
Follow-up & long-term care
A follow-up duplex ultrasound scan is often arranged to check whether the treated veins have closed and to look for clot problems, and to plan any further sessions. Report calf pain, swelling, breathlessness or stroke-like symptoms straight away rather than waiting.
- Expect that one or more top-up sessions may be needed over time
- Stay active and keep to a healthy weight to reduce pressure on leg veins
- Use compression stockings if advised for symptoms or swelling
- Seek review if aching, swelling or new bulging veins return
Repeat, follow-on and what comes next
- Repeat sessions are commonly needed because veins may only partly close or can reopen.
- Treated veins can recanalise (reopen) over time, more often than after heat ablation.
- Lumpy trapped blood may be drained with a needle to ease discomfort and reduce staining.
- New varicose veins can appear over the years and may prompt further treatment.
Ask what happens if the result is unclear or needs repeating, and what is included if further tests or follow-up are needed.
What good aftercare looks like
- A follow-up scan to confirm veins have closed and to look for clot problems.
- Clear written advice on compression, staying mobile and recognising clot and stroke warning signs.
- A named contact and out-of-hours route for problems.
- An honest plan for further sessions and which veins are or are not NHS-funded.
- Review of risk factors such as PFO, migraine, hormone medicines and previous clots.
What affects the cost
Costs vary a great deal between people and providers, and we don't publish prices. What matters is understanding what drives the cost and making sure your quote is complete. The main things that affect it:
- The number of sessions likely to be needed
- How many veins and which legs are treated
- The duplex ultrasound scan and who performs and reports it
- The specialist's fee and the clinic or facility fee
- Whether it is combined with ablation or phlebectomy
- Follow-up scans and review appointments
- Compression stockings and aftercare
- The specialist's fee and the facility fee
- Whether the price is per session or per course, given repeat sessions are common
- The cost of the duplex ultrasound scan and its reporting
- Follow-up scans and review appointments
- What happens, and what it costs, if veins reopen or further treatment is needed
- Compression stockings and the cancellation policy
On the NHS? Foam sclerotherapy is available on the NHS for symptomatic varicose veins when a heat treatment is unsuitable; private care may be chosen for speed or convenience, but cosmetic-only treatment of thread veins is not usually NHS-funded.
You're entitled to your total cost in writing — including reports, follow-up and what happens if the result is inconclusive — before you decide.
Consent traps and marketing red flags
These are not small details. They are often where patients lose choice, time to reflect, or realistic expectations.
Consent traps
- Not being told that more than one session is often needed.
- No mention of brown skin staining and lumpy veins as common, expected effects.
- Failing to ask about migraine with aura, a known PFO, or previous clots before treating.
- No discussion of the rare but serious neurological and clot risks NICE highlights.
- Being offered foam when a more durable heat treatment is actually suitable.
Marketing red flags
- "No-risk" or "usually not painful" claims that ignore staining, clots and rare serious reactions.
- Promises that one session will clear all veins permanently.
- Not mentioning that veins can reopen and repeat treatment is common.
- No duplex ultrasound assessment in the pathway.
- Blurring foam sclerotherapy with cosmetic spider-vein treatment to imply guaranteed cosmetic results.
Choosing a specialist safely
- Check the specialist is on the GMC Specialist Register for this area.
- Make sure they work at a CQC-registered service, and look for membership of the relevant Royal College or professional body.
- You're entitled to time to consider and to have your questions answered before you agree — the specialist who looks after you should explain it, not a salesperson.
- Be wary of pressure: time-limited offers or deposits taken before you've had time to think are red flags, not bargains.
- You're entitled to your total cost in writing — including any follow-up — before you decide.
Questions to ask your medical professional
Take this to your consultation. A good specialist will welcome every one of these.
- Have my leg veins been scanned, and is foam the most suitable option for me?
- How many sessions am I likely to need?
- How likely am I to get skin staining or lumpy veins, and how long do they last?
- Do I have any risk factors, such as migraine with aura or a known PFO, that change the risks?
- What is my personal clot risk and what will reduce it?
- What are the warning signs that should make me seek urgent help?
- Are you on the GMC Specialist Register for this area, and which Royal College or professional body are you a member of?
- Will you be the specialist who carries out my injection, and who looks after me afterwards?
- What are the risks for someone like me, and how often do your own patients have a problem or need it repeated or redone?
- What does a realistic result look like — and what can this injection not achieve?
- What are my options, including waiting, doing nothing for now, or choosing a different approach?
- Can I have written information, results and aftercare instructions in a format I can use, including any accessibility or communication support I need?
- What is the total cost in writing, including any follow-ups, and how much time do I have to decide?
Frequently asked questions
Is foam sclerotherapy available on the NHS?
Does the injection hurt?
Why do I have brown marks after treatment?
Will I need more than one session?
What are the serious risks I should know about?
How is this different from treatment for spider veins?
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How we made this page
Medically reviewed by a GMC-registered consultant. Written in plain English, checked against NHS, NICE, GMC and relevant Royal College / specialist-society guidance, and kept under review. No clinic paid to appear on this page, and we publish no pricing. This is general information to help you prepare — it is not a substitute for advice from your own clinician. How we review our guides →
Source hierarchy: UK regulator and NHS/NICE guidance first, then relevant Royal College or specialist-society guidance, then peer-reviewed evidence for procedure-specific figures where available.
Sources & standards: NICE CG168 — Varicose veins: diagnosis and management NICE IPG440 — Ultrasound-guided foam sclerotherapy for varicose veins NHS — Varicose veins: treatment Circulation Foundation (Vascular Society) — Varicose veins & leg ulcers Foam sclerotherapy for lower-limb varicose veins (review) — PMC
Reviews reflect patients' experience of care, not clinical outcomes. For procedure volumes and outcome data see PHIN.
Last medically reviewed 2026-09-21. Spotted something wrong or out of date? Report an error in this guide.
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