Pitting edema is swelling caused by excess fluid trapped in your body’s tissues that leaves a visible dent when you press on it. If you push a finger into the swollen area and an indentation stays behind after you release, that’s the “pitting” part. It most commonly shows up in the legs, ankles, and feet, though it can occur anywhere. The dent forms because the trapped fluid has a relatively low protein concentration, making it easy to displace temporarily under pressure.
Why Fluid Builds Up in Tissues
Your body constantly moves fluid between blood vessels and the surrounding tissue. A balance of pressures inside and outside your capillaries controls this exchange: blood pressure pushes fluid out, while proteins in your blood pull fluid back in. A third system, the lymphatic network, acts as a drain for any excess that slips through.
Pitting edema develops when something disrupts this balance. That can mean higher pressure inside the blood vessels (forcing more fluid out), lower protein levels in the blood (so less fluid gets pulled back), leakier capillary walls, or a lymphatic system that can’t keep up. Sodium plays a role too. When your kidneys retain extra sodium, water follows it, expanding the volume of fluid that ends up in tissue spaces. In many cases, more than one of these mechanisms is happening at the same time.
Common Causes
Heart Failure
When the heart can’t pump blood efficiently, blood backs up in the veins. That raises pressure in the capillaries of the legs and feet, pushing fluid into surrounding tissue. The swelling is often worse at the end of the day after hours of standing or sitting and may improve overnight when the legs are level with the heart.
Kidney Disease
Damaged kidneys struggle to remove sodium and water from the blood, leading to fluid overload throughout the body. Swelling typically appears in the legs and around the eyes. In nephrotic syndrome, a specific form of kidney damage, the kidneys also leak large amounts of protein into the urine. That drops protein levels in the blood, reducing the force that normally pulls fluid back into capillaries.
Liver Disease
Advanced liver disease reduces production of albumin, the main protein responsible for keeping fluid inside blood vessels. Low albumin levels allow fluid to seep into tissues more easily, often causing swelling in the legs and fluid accumulation in the abdomen.
Venous Insufficiency
Veins in the legs contain one-way valves that help push blood back toward the heart. When these valves weaken or fail, blood pools in the lower legs, raising capillary pressure locally. This is one of the most common causes of chronic leg swelling and can result from prior blood clots, prolonged standing, or simply aging. The edema tends to worsen throughout the day and improve with elevation.
Medications
Certain blood pressure medications, particularly calcium channel blockers like amlodipine, are well-known culprits. In one multicenter study, peripheral edema developed in nearly 39% of patients taking these drugs, with higher doses carrying a greater risk (about 43% at 10 mg daily versus 33% at 5 mg). Anti-inflammatory drugs, some diabetes medications, and hormone therapies can also cause fluid retention.
Pregnancy and Prolonged Sitting
Mild pitting edema during pregnancy is common and usually harmless, driven by increased blood volume and pressure from the growing uterus on pelvic veins. Similarly, sitting for long stretches, especially during flights, can cause temporary swelling in the feet and ankles that resolves with movement.
How Pitting Edema Is Tested
The test is simple. A clinician presses a finger firmly against a bony area, usually the inside of the ankle, the shin bone, or the top of the foot, and holds pressure for about 20 seconds. After releasing, they observe how deep the dent is and how long it takes to refill.
The results are graded on a scale from 1+ to 4+ based on how far the skin indents:
- 1+: 2 to 4 mm deep, a slight dent
- 2+: 4 to 6 mm deep, a noticeable dent
- 3+: 6 to 8 mm deep, the area looks visibly swollen
- 4+: 8 mm or more, deep indentation with significant swelling
This grading helps track whether swelling is improving or worsening over time. Your doctor will also note the location of the edema (one leg versus both), whether it extends above the knee, and how it changes throughout the day, because all of these details point toward different underlying causes.
When Swelling in One Leg Is a Warning Sign
Pitting edema that appears suddenly in just one leg deserves prompt attention, because it can signal a deep vein thrombosis (DVT), a blood clot in the veins of the leg. Key features that raise suspicion for DVT include calf pain or tenderness, skin that feels warm to the touch, visible swelling confined to the affected leg, and a calf circumference more than 3 cm larger than the other side. In severe cases the leg may take on a bluish color. A DVT can become dangerous if part of the clot breaks loose and travels to the lungs, so new, unexplained one-sided leg swelling warrants medical evaluation the same day.
Swelling that affects both legs equally is more likely related to a systemic issue like heart failure, kidney disease, or medication side effects rather than a clot, though it still needs investigation if it’s new or worsening.
Treatment Depends on the Cause
Because pitting edema is a symptom rather than a disease, management focuses on whatever is driving the fluid buildup. For heart failure, the main approach involves medications that help the body shed excess sodium and water. For liver-related edema, a different class of water pills is often used, sometimes alongside albumin infusions to restore protein levels in the blood. Kidney disease management focuses on controlling sodium intake and treating the underlying damage.
If a medication is the cause, switching to an alternative often resolves the problem within days to weeks.
What You Can Do at Home
Compression stockings are one of the most effective tools for venous edema, helping squeeze fluid back into circulation. They work well but require consistency; many people find them uncomfortable or difficult to put on, which limits their benefit in practice. Elevating your legs above heart level when resting encourages fluid to drain back toward the center of the body. Reducing sodium in your diet limits how much water your body retains. Regular movement, even simple calf raises or short walks, activates the muscles that pump blood back up the legs.
Elastic bandage wraps can also reduce swelling. In one study of patients awaiting liver transplantation, wearing elastic wraps for eight hours significantly reduced both edema and pain in the legs. Newer approaches like electrical calf muscle stimulation and negative-pressure lymphatic drainage devices are being explored, though they aren’t yet standard care.
Pitting vs. Non-Pitting Edema
Not all swelling pits when you press on it. Non-pitting edema feels firm and doesn’t leave a dent, typically because the fluid trapped in the tissue has a high protein content or the tissue itself has thickened. This type is more common in lymphedema (where the lymphatic drainage system is blocked or damaged) and in severe, long-standing thyroid disease. The distinction matters because pitting and non-pitting edema point to different causes and respond to different treatments. However, the line isn’t always clean: chronic pitting edema can gradually become non-pitting over time as proteins accumulate in the tissue and fibrosis develops.