Understanding Sclerotherapy: How It Works
Sclerotherapy is a minimally invasive medical procedure used to treat and eliminate varicose veins and spider veins [1.2.4]. The fundamental principle involves injecting a special solution, called a sclerosant, directly into the targeted vein [1.2.4]. This medication irritates the lining of the blood vessel (the endothelium), causing it to swell, stick together, and eventually seal shut [1.2.4]. Once the vein is closed, blood flow is naturally rerouted to healthier veins [1.3.4]. Over time, the collapsed vein turns into scar tissue and is absorbed by the body, fading from view [1.2.4]. This process is highly effective, with studies showing that 50% to 80% of injected veins can be eliminated in a single session [1.3.2].
What Medication is Injected in Sclerotherapy? A Detailed Look
The choice of medication depends on several factors, including the size and location of the vein, the patient's medical history, and the physician's preference. Sclerosants are generally categorized into three main types: detergents, osmotic agents, and chemical irritants [1.2.2].
Detergents: The Most Common Class
Detergent sclerosants are the most widely used agents in modern practice. They work by disrupting the cells on the vein's inner lining [1.4.2]. Two leading FDA-approved detergent medications are Polidocanol and Sodium Tetradecyl Sulfate.
- Polidocanol (Asclera®, Aethoxysklerol®): Approved by the FDA in 2010, polidocanol has become a preferred agent in many vein centers [1.2.2]. It is known for being effective and relatively painless upon injection [1.4.1]. It is indicated for treating uncomplicated spider veins (less than 1mm in diameter) and small varicose (reticular) veins (1-3mm in diameter) [1.2.1]. One of its key advantages is a low risk of skin necrosis or ulceration, even if accidentally injected outside the vein [1.2.2, 1.4.1].
- Sodium Tetradecyl Sulfate (Sotradecol®): This is another effective detergent sclerosant. It is available in different concentrations, allowing practitioners to dilute it for use in various vein sizes, from small spider veins to larger, deeper veins [1.2.2]. While highly effective, it may be associated with a higher incidence of hyperpigmentation and potential for allergic reactions compared to polidocanol [1.2.2].
Osmotic Agents
Osmotic agents work by dehydrating and destroying the endothelial cells through osmosis.
- Hypertonic Saline: This is a concentrated salt solution that was widely used in the past [1.2.2]. It is very inexpensive and carries no risk of allergic reaction [1.3.3]. However, its use has declined because injections can be painful, causing intense burning and muscle cramping [1.3.3]. There is also a higher risk of ulceration if the solution leaks outside the vein [1.3.3].
Chemical Irritants
This category includes substances that cause direct damage to the vein wall.
- Glycerin (Chromated Glycerin): Often used in Europe, glycerin is a milder agent ideal for very small spider veins and capillaries [1.3.6, 1.4.7]. It is associated with a lower risk of staining (hyperpigmentation) and telangiectatic matting (the formation of new, tiny blood vessels) [1.3.6]. However, it can be painful on injection and is not effective for larger veins [1.4.7].
Comparison of Common Sclerotherapy Agents
| Agent | Class | FDA Approved | Primary Use | Pros | Cons |
|---|---|---|---|---|---|
| Polidocanol (Asclera®) | Detergent | Yes [1.2.2] | Spider & Reticular Veins | Generally painless, rare ulceration, low necrosis risk [1.2.2, 1.4.1] | Can cause allergies, hyperpigmentation, and matting [1.2.2] |
| Sodium Tetradecyl Sulfate (Sotradecol®) | Detergent | Yes [1.2.6] | Spider, Reticular & Larger Veins | Highly effective, less matting than some agents [1.2.2] | Can cause hyperpigmentation, ulceration, and allergies [1.2.2] |
| Hypertonic Saline | Osmotic | No (Used Off-Label) | Small Spider Veins (<1mm) | Inexpensive, no allergic reactions [1.3.3] | Painful injection, muscle cramping, higher risk of ulceration and hyperpigmentation [1.2.2, 1.3.3] |
The Role of Foam Sclerotherapy
For larger varicose veins, liquid sclerosants can be mixed with air or a physiological gas (like carbon dioxide) to create a foam consistency, similar to shaving cream [1.2.4, 1.2.5]. This technique is known as foam sclerotherapy. The foam displaces blood within the vein rather than mixing with it, allowing for better contact between the medication and the vein wall [1.2.4]. This makes the treatment more effective for larger veins and often requires fewer treatment sessions compared to liquid sclerotherapy [1.7.5, 1.3.1]. Both polidocanol and sodium tetradecyl sulfate are commonly used to create this foam [1.2.5].
The Procedure and Aftercare
A sclerotherapy session is a quick outpatient procedure, typically lasting 15 to 45 minutes [1.2.1, 1.6.2]. The provider cleans the area and uses a very fine needle to inject the sclerosant into the targeted veins [1.2.1]. After the injections, pressure is applied, and the patient is usually required to wear compression stockings for several days to two weeks [1.5.3, 1.6.2]. This compression is crucial for achieving the best results [1.5.4]. Patients are encouraged to walk immediately after the procedure but should avoid strenuous exercise, hot baths, and sun exposure for a week or two [1.5.2, 1.5.4].
Conclusion: Choosing the Right Sclerosant
Ultimately, the question of what medication is injected in sclerotherapy is answered by a qualified healthcare professional. The choice between polidocanol, sodium tetradecyl sulfate, hypertonic saline, or another agent is tailored to the individual. Factors like vein size, patient allergies, and skin type all play a role in the decision [1.2.2]. Modern detergent sclerosants like polidocanol and STS, often used as liquid or foam, represent the standard of care, offering a safe and effective solution for the millions affected by spider and varicose veins.
For more information from an authoritative source, you can visit the Society for Vascular Surgery.
