Sclerotherapy Explained: Uses, Procedure, Risks, and Recovery

Sclerotherapy is a minimally invasive treatment used to reduce the appearance of spider veins and some varicose veins. This guide explains what sclerotherapy is, who may be considered for it, how the procedure is performed, common agents and techniques, potential risks, and typical recovery steps.

Sclerotherapy: definition and common uses

Sclerotherapy is primarily used to treat cosmetic spider veins and symptomatic varicose veins that cause aching, swelling, or skin changes. The procedure aims to close abnormal veins so blood is redirected to healthier veins. Diagnosis often includes a clinical exam and duplex ultrasound to map venous anatomy and rule out deep vein thrombosis before treatment.

How sclerotherapy works

Mechanism of action

A sclerosant is injected into the target vein to irritate the lining (endothelium), causing the vein to seal shut. Over weeks to months the treated vein is reabsorbed by the body and fades. Compression after treatment helps collapse the treated vessel and supports healing.

Common sclerosant agents

Frequently used agents include polidocanol and sodium tetradecyl sulfate. Hypertonic saline solutions and foam preparations are other options; foam allows treatment of larger or longer veins by increasing contact time with the vein wall. Selection of agent and concentration depends on vein size, location, and practitioner preference.

Types of sclerotherapy and techniques

Liquid sclerotherapy

Liquid sclerosants are suitable for small spider veins and short segments of varicose veins. Multiple injections are often required in a single session to treat the network of visible veins.

Foam sclerotherapy

Foam is created by mixing a sclerosant with air or gas to form bubbles; it displaces blood inside the vein and allows longer contact with the vessel wall. Foam is commonly used for larger varicose veins and is sometimes combined with compression or ambulatory techniques.

Ultrasound-guided sclerotherapy

Ultrasound-guided injections are used for veins that are not visible at the skin surface. Duplex ultrasound guides needle placement, monitors sclerosant distribution, and assesses for reflux in the saphenous veins.

The procedure: what to expect

Before treatment

Assessment typically includes medical history, venous examination, and duplex ultrasound. Patients should inform the clinician about current medications, allergies, pregnancy status, and history of clotting disorders.

During treatment

Sclerotherapy is usually performed in an outpatient clinic. Skin cleansing is followed by a series of small injections. Sessions often last 15–60 minutes depending on the number of veins treated. Local anesthetic is rarely needed. Patients can usually walk immediately afterward.

Aftercare and recovery

Compression stockings or bandaging are commonly recommended for a period after treatment to improve outcomes. Mild bruising, staining (hyperpigmentation), itching, or cramping can occur and generally resolves over weeks to months. Multiple treatment sessions may be required to achieve desired results.

Risks, side effects, and when to seek help

Common and expected effects

Common effects include transient bruising, small skin ulceration at the injection site, and brownish skin discoloration along the treated vein. Matting (development of fine new vessels) is a possible cosmetic side effect.

Less common and serious complications

Allergic reactions, infection at the injection site, or thrombosis in treated veins can occur but are uncommon. Deep vein thrombosis and pulmonary embolism are rare. Any sudden calf pain, shortness of breath, or signs of infection should prompt urgent medical assessment.

Choosing a provider and clinical guidance

Providers who perform sclerotherapy include vascular surgeons, phlebologists, interventional radiologists, and dermatologists with venous expertise. Credentialing and experience with ultrasound-guided techniques are important. Clinical guidelines and audits from professional societies such as the American Vein & Lymphatic Society (AVLS) and regional vascular surgery associations provide standards for practice.

Evidence and official resources

National health services and vascular societies publish patient information and guidance on varicose vein treatments and sclerotherapy. For official patient-facing information, see the NHS guidance on varicose vein treatment:

NHS — Varicose veins: treatment

Practical considerations and cost

Availability, cost, and clinical eligibility vary by health system and insurer. Some payers cover sclerotherapy for symptomatic veins but not for purely cosmetic treatment. A prior duplex ultrasound and documented symptoms often influence coverage decisions. Discuss expected outcomes, number of sessions, and price estimates during the consultation.

When sclerotherapy may not be appropriate

Large, bulging varicose veins or significant saphenous vein reflux may be better treated with endovenous thermal ablation or surgical options. Pregnancy is generally a contraindication to elective sclerotherapy until after delivery.

Follow-up and long-term outlook

Follow-up appointments evaluate response and address side effects. Treated veins can recur, and new veins may develop over time; long-term management may include lifestyle measures, weight control, exercise, and continued use of compression where advised.