Compression therapy is a widely used non-surgical method for managing varicose veins and chronic venous insufficiency. This approach uses specialized elastic garments to apply controlled pressure to the limbs, counteracting the effects of gravity on blood flow. This external pressure gently squeezes the leg tissues, supporting vein walls and improving the return of deoxygenated blood toward the heart. Compression mitigates symptoms like leg fatigue, aching, and swelling by preventing the pooling of blood in the lower extremities.
Defining Compression Pressure Levels (The mmHg Scale)
The pressure applied by compression garments is precisely measured using the unit millimeters of mercury (mmHg). This is the same pressure scale utilized by medical professionals when measuring blood pressure. In the context of compression stockings, the mmHg value indicates the amount of gradient pressure the garment exerts on the limb.
This pressure is applied in a graduated manner, meaning it is strongest at the ankle and gradually decreases as the garment moves up the leg toward the knee or thigh. This deliberate pressure differential is designed to mimic the action of the calf muscles, assisting the upward flow of blood against gravity. Compression therapy is categorized into standard pressure ranges that guide selection based on need. The most common international ranges are 8–15 mmHg, 15–20 mmHg, 20–30 mmHg, and 30–40 mmHg.
Selecting the Right Pressure for Varicose Vein Severity
The severity of venous disease dictates the required level of compression, making the pressure range the most important factor in effective therapy. Mild compression (8–15 mmHg) is often recommended for preventive measures, such as addressing minor leg fatigue or swelling experienced during long periods of sitting or standing. This lower range can also be helpful for managing minor spider veins.
For early-stage varicose veins, mild edema, and to support the legs during long-distance travel, a moderate pressure of 15–20 mmHg is appropriate. This level is frequently used following procedures like sclerotherapy to help keep the treated veins closed.
A firm pressure of 20–30 mmHg is indicated for treating moderate to severe varicose veins, managing moderate edema, or during recovery after venous surgery. This strength provides the necessary external force to manage more established venous insufficiency. Levels in the 30–40 mmHg range and higher are reserved for severe chronic venous insufficiency, significant edema, lymphedema, or the management of actively healing venous ulcers.
Over-the-Counter vs. Prescription Strength Compression
Compression garments are differentiated by their pressure level and accessibility, falling into over-the-counter (OTC) or prescription categories. Stockings with a pressure of 20 mmHg and below are generally available without a doctor’s order and are suitable for general wellness, minor symptoms, and preventive use.
Higher compression levels, particularly those starting at 30–40 mmHg, are considered medical-grade and require a prescription. Stronger compression levels carry a greater risk if used improperly, especially in individuals with underlying arterial disease where high pressure could restrict necessary blood flow. Prescription strength garments also undergo more rigorous testing to ensure they deliver the advertised, precise pressure gradient consistently.
Medical supervision ensures that the chosen pressure level is safe and effective for the specific diagnosis, especially when treating severe conditions. Pharmacists or certified fitters often dispense these higher-strength garments under a doctor’s guidance.
The Critical Role of Proper Sizing and Fit
The therapeutic effectiveness of any compression garment is entirely dependent on its correct sizing and fit. An ill-fitting stocking can be ineffective or even harmful, making precise measurement as important as pressure selection. The primary measurement points include the circumference of the ankle at its narrowest point and the calf at its widest point.
For garments that extend beyond the knee, the circumference of the thigh and the length of the leg are also required. Measurements should be taken first thing in the morning, before the legs have had a chance to swell from daily activity, to ensure the most accurate sizing. A stocking that is too loose will fail to apply the necessary gradient pressure, rendering the therapy ineffective.
Conversely, a garment that is too tight can create a tourniquet effect, potentially restricting blood flow at the top edge or bunching uncomfortably. Seeking a professional fitting from a certified fitter is recommended for all medical-grade and prescription-level compression.