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.
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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.
Table of contents
1. What exactly is sclerotherapy?
2. What types of veins does sclerotherapy treat?
3. How does sclerotherapy work?
4. Is sclerotherapy the same as vein surgery?
5. Does sclerotherapy hurt?
6. How many sclerotherapy sessions are needed?
7. What results can patients expect?
8. Are there side effects or risks?
9. Do spider veins come back after sclerotherapy?
10. When is a vein evaluation recommended before sclerotherapy?
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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.
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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.
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About the Medical Team at Vein Treatment Clinic
Vein Treatment Clinic is powered by VIP Medical Group and built around a single guiding principle: deliver the highest standard of vein care using an academic, evidence-based approach combined with the most advanced, minimally invasive technology available today.
Clinical leadership at Vein Treatment Clinic is guided by board-certified vein specialists, including Dr. Michael Nguyen, whose training and experience help shape the clinic’s rigorous standards of care.
All physicians at Vein Treatment Clinic follow a structured, highly standardized clinical model. This includes ongoing training in the latest non-surgical vein treatments, continuous review of emerging research, and strict adherence to proven safety and quality protocols.
Patients benefit from a team-based model of care where expertise is shared, best practices are consistently applied, and treatment recommendations are driven by data, experience, and long-term results.

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