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What Is Sclerotherapy?
Medically verified
Last updated on 1/29/2026
By Dr. Michael Nguyen
Vein Doctor at Vein Treatment Clinic
Harvard Medical School
Board Certified by the American Board of Venous and Lymphatic Medicine
Sclerotherapy is a common, non-surgical treatment used to treat spider veins and some small varicose veins by closing them from the inside.
Many patients are unfamiliar with how sclerotherapy works and often wonder whether injections are safe, effective, or painful.
This page explains what sclerotherapy is, how it works, which veins it treats best, and what patients can expect before and after treatment.
If you’re unsure whether sclerotherapy is appropriate for your veins, a vein evaluation can help determine the best treatment plan.
What exactly is sclerotherapy?
Sclerotherapy is a treatment in which a medication is injected directly into a vein using a very fine needle.
The medication irritates the vein lining, causing the vein to close and eventually be absorbed by the body.
What types of veins does sclerotherapy treat?
Sclerotherapy is most commonly used to treat spider veins and small varicose veins close to the skin surface.
Larger varicose veins usually require treatment of underlying reflux first before sclerotherapy is used as a finishing step.
How does sclerotherapy work?
Once injected, the sclerosing solution causes the vein walls to stick together, stopping blood flow through that vein.
Blood is naturally redirected to healthier veins, and the treated vein gradually fades over weeks to months.
Symptom Checker
Is sclerotherapy the same as vein surgery?
No. Sclerotherapy is not surgery and does not involve incisions or general anesthesia.
It is typically performed in an office setting and allows patients to resume normal activities quickly.
Does sclerotherapy hurt?
Most patients describe sclerotherapy as causing mild discomfort, often described as a small pinch or brief stinging.
Discomfort is usually short-lived and well tolerated.
How many sclerotherapy sessions are needed?
The number of sessions depends on how many veins are present and how the veins respond to treatment.
Many patients require multiple sessions for optimal cosmetic and symptom improvement.
Before
After
A 37-year-old patient visited our Vein Treatment Clinic, seeking relief from unsightly and painful varicose and spider veins. We performed radiofrequency ablation and sclerotherapy treatments, significantly improving the veins’ appearance and completely eliminating discomfort. The patient is now enjoying a more active and pain-free lifestyle.
Before
After
A 69 year-old patient visited our California Vein Clinic, embarrassed by spider veins that had impacted their self-esteem. We performed radiofrequency ablation and sclerotherapy treatments, leaving their legs smooth and healthy. The patient now feels more confident, thanks to this transformative treatment.
Before
After
This 84 year-old patient at our New Jersey Vein Treatment Clinic came in with spider veins that had affected their daily routine. We used radiofrequency ablation and sclerotherapy treatments to relieve discomfort and restore both their leg health and confidence. The patient now enjoys a more active and fulfilling lifestyle, free from pain.
Before
After
At our Long Island Vein Clinic, we treated this 75 year-old patient with spider veins using radiofrequency ablation and sclerotherapy. These minimally invasive treatments improved both the patient’s appearance and overall well-being, offering transformative results.
Before
After
This 75 year-old patient visited our Long Island Vein Treatment Clinic with painful spider veins. We used radiofrequency ablation and sclerotherapy, minimally invasive treatments, to eliminate the veins and restore comfort and confidence. The patient experienced life-changing results
What results can patients expect?
Spider veins typically begin to fade within several weeks after treatment.
Full results may take a few months, and some veins may require additional treatment.
Spider Vein before and after treatment pictures.
Results may vary according to each case.
Spider Vein before and after treatment pictures.
Results may vary according to each case.
Are there side effects or risks?
Common side effects include mild bruising, redness, or tenderness at injection sites.
Serious complications are uncommon when sclerotherapy is performed by experienced specialists.
Do spider veins come back after sclerotherapy?
Treated veins usually do not return.
However, new spider veins can form over time, especially if underlying vein pressure is present.
When is a vein evaluation recommended before sclerotherapy?
A vein evaluation is recommended when spider veins are associated with pain, swelling, or repeated recurrence.
Ultrasound helps determine whether deeper vein reflux should be treated first.
Get a Peek Inside Your Veins—Book Your Ultrasound Evaluation.