A compression bandage is a stretchy or semi-rigid wrap applied to a limb to exert controlled external pressure, pushing fluid back toward the heart and improving blood flow. These bandages are a cornerstone treatment for conditions like venous leg ulcers, chronic swelling, and lymphedema. They work by squeezing the veins and tissues beneath the skin at specific pressures, typically ranging from 18 to over 49 mmHg depending on the clinical need.
How Compression Bandages Work
Your veins rely on one-way valves and the squeezing action of surrounding muscles to push blood back up toward the heart. When those valves weaken or fail, blood pools in the lower legs, pressure builds inside the veins, and fluid leaks into surrounding tissues. That’s what causes the swelling, skin changes, and slow-healing wounds associated with venous disease.
A compression bandage counteracts this by applying enough external pressure to narrow the veins and speed up blood flow. For this to work, the bandage pressure has to exceed the pressure inside the veins themselves. Research shows that initial narrowing of leg veins occurs at pressures of 30 to 40 mmHg in both sitting and standing positions. Full compression of the veins requires higher pressures when you’re upright: around 50 to 60 mmHg while sitting and about 70 mmHg while standing, compared to just 20 to 25 mmHg when lying down. This is why compression therapy behaves differently depending on your position and activity level.
The bandage also supports what’s called the calf muscle pump. Every time you walk or flex your calf, the muscles squeeze the deep veins and push blood upward. A firm bandage around the leg makes this pump more efficient because it gives the muscles something to push against, creating higher pressure spikes during movement that drive blood flow more effectively.
Short-Stretch vs. Long-Stretch Bandages
Compression bandages fall into two broad categories based on how much they stretch, and this distinction matters because it changes how the bandage behaves on your leg.
Short-stretch bandages have limited elasticity. They feel firm and resist expansion, which means they generate high pressure when you move (called “working pressure”) but drop significantly when you lie down or rest. Because the leg can’t expand easily against the stiff material during walking, short-stretch bandages produce larger pressure swings with each step. This makes them especially effective for improving the calf muscle pump and reducing venous pressure during activity. At rest, they’re quite comfortable because the pressure drops substantially.
Long-stretch bandages are more elastic and maintain steadier compression regardless of whether you’re moving or at rest. They sustain their pressure better than stiffer materials over time, which can be useful when consistent compression is needed around the clock. However, they don’t generate the same high-pressure peaks during movement that short-stretch bandages do.
In practice, the choice between the two depends on the condition being treated, how mobile the patient is, and whether the priority is active pressure during movement or sustained pressure at rest.
Multilayer Compression Systems
Many clinical compression bandages aren’t a single wrap but a system of multiple layers, each serving a different purpose. A common four-layer system consists of orthopedic wool as the innermost layer (to protect bony areas and redistribute pressure), a crepe bandage for absorbency and light support, an elastic bandage for the main compression, and an outer elastic cohesive bandage to hold everything in place. Together, these layers form what amounts to a semi-rigid sleeve that conforms to the contours of the leg and maintains a consistent pressure profile as you move throughout the day.
These multilayer systems that exert pressures over 40 mmHg have been shown to reduce venous hypertension during walking and improve overall venous pumping function. They’re commonly used for treating venous leg ulcers and managing moderate to severe swelling.
The Unna Boot
One specialized variant worth knowing about is the Unna boot, a compression dressing specifically designed for venous stasis ulcers and acute stasis dermatitis. It uses an inner layer of gauze bandage soaked in a paste containing zinc oxide, calamine, glycerin, and gelatin, wrapped with an outer elastic layer that provides graded compression. The zinc oxide paste helps soothe irritated skin while the outer layer supplies the mechanical compression. Because it hardens somewhat after application, the Unna boot functions as a semi-rigid dressing that patients typically wear for about a week before it’s changed.
Compression Pressure Classes
Compression garments and bandages are categorized into four standard pressure classes, each suited to different severity levels:
- Class I (18 to 21 mmHg): Light compression for mild swelling, tired legs, or prevention during long periods of sitting or standing.
- Class II (23 to 32 mmHg): Moderate compression for varicose veins, mild to moderate edema, and post-procedure recovery.
- Class III (34 to 46 mmHg): Firm compression for chronic venous insufficiency, active venous ulcers, and lymphedema.
- Class IV (above 49 mmHg): Very firm compression reserved for severe lymphedema and the most advanced venous conditions.
Higher classes aren’t automatically better. Using too much compression on a limb with poor arterial circulation can restrict blood supply and cause serious harm, which is why proper assessment matters before starting compression therapy.
Wrapping Techniques
How the bandage is applied affects the pressure it delivers just as much as the bandage type itself. The two main techniques are spiral wrapping and figure-of-eight wrapping.
The spiral technique leaves small gaps between individual wraps as the bandage winds up the leg. It’s considered a safe and comfortable application method, easier to control, and produces more predictable pressure levels. The figure-of-eight technique, where the bandage crosses over itself in an X pattern, delivers significantly higher compression at the ankle and lower leg. In one comparison, the figure-of-eight produced pressures roughly 20 mmHg higher at the ankle and 22 mmHg higher at the lower calf than spiral wrapping. However, it also created pressure hotspots, particularly over the Achilles tendon, and is harder to apply consistently. For this reason, figure-of-eight application with high-compression bandages is generally not recommended due to the risk of dangerously high localized pressure.
Conditions Treated With Compression
Compression therapy is the foundation of treatment for venous leg ulcers, both for healing active wounds and preventing recurrence. Without compression, venous ulcers tend to recur because the underlying problem (high venous pressure in the legs) remains uncorrected. Compression doesn’t fix the damaged valves, but it compensates for them mechanically.
Beyond venous ulcers, compression bandages are used to manage lymphedema (chronic swelling caused by a compromised lymphatic system), reduce post-surgical or post-injury edema, treat inflammatory wounds, and prevent blood clots in people who are immobile for extended periods. Athletes sometimes use light compression wraps to manage acute sprains and strains, though the therapeutic pressures involved are much lower than those used for venous disease.
When Compression Is Not Safe
Compression is not appropriate for everyone. The most important concern is peripheral arterial disease, where the arteries supplying the legs are already narrowed. Adding external compression to a limb with poor arterial inflow can starve the tissues of oxygen, potentially leading to tissue death.
Current guidelines identify compression as contraindicated when the ankle-brachial index (a simple ratio comparing blood pressure at the ankle to blood pressure in the arm) falls below 0.5, or when ankle arterial pressure is below 60 mmHg. Before starting compression therapy, a healthcare provider will typically check arterial circulation in the legs to rule out significant arterial disease. Other contraindications include uncontrolled heart failure, active skin infections in the area to be compressed, and certain nerve conditions that would prevent you from feeling warning signs like pain or numbness under the bandage.