Swelling from a typical injury or strain should peak within one to three days and gradually resolve over the following few weeks. If your swelling hasn’t gone down within that window, something may be preventing your body from clearing the excess fluid, and the longer it persists, the more likely it is to cause secondary problems. What those problems look like depends on whether the swelling is from a local injury that isn’t healing properly, a drainage issue in your veins or lymph system, or a sign of something happening with your heart, kidneys, or liver.
How Long Swelling Normally Lasts
After a soft tissue injury like a sprain, strain, or bruise, swelling starts within about an hour as blood vessels in the area become more permeable and push fluid into the surrounding tissue. In mild injuries, that permeability returns to normal in 20 to 30 minutes. The inflammatory response itself peaks between days one and three, and the acute phase typically wraps up within about seven days. Full resolution of swelling can take a few weeks, but the trend should be clearly improving during that time.
If swelling is still at its peak after a week, or hasn’t budged after two to three weeks, that’s outside the normal healing curve. It doesn’t automatically mean something dangerous is happening, but it does mean your body either can’t clear the fluid or something is continuously producing it.
Skin Changes and Tissue Damage
One of the most visible consequences of swelling that sticks around is what it does to your skin. Chronically swollen tissue, especially in the lower legs, can develop a condition called stasis dermatitis. The skin becomes discolored, itchy, and inflamed as pressure from the trapped fluid damages small blood vessels. Red blood cells leak into the tissue and break down, leaving behind iron deposits that stain the skin a reddish-brown color.
Over time, the deeper layers of tissue start to harden and scar. In advanced cases, the fat layer beneath the skin becomes so fibrotic that the lower leg takes on what’s described as an “inverted champagne bottle” shape: the ankle and lower calf become tight and narrow while the area above stays swollen. If the underlying cause isn’t addressed, the skin can eventually break down into open wounds called venous ulcers. These ulcers are notoriously slow to heal because the same poor circulation that caused them also starves the tissue of what it needs to repair itself.
Increased Risk of Infection
Swollen tissue is more vulnerable to bacterial infection, particularly cellulitis. The reason is surprisingly direct: your lymphatic system doesn’t just drain fluid, it also carries immune cells and infection-related signals to your lymph nodes. When fluid is backed up, that immune trafficking is disrupted. The tissue becomes a warm, protein-rich environment with a compromised local immune response, which is essentially an open invitation for bacteria. People with chronic swelling in their legs experience recurrent cellulitis at significantly higher rates, and each infection can further damage the lymphatic vessels, creating a cycle where the swelling worsens and infections become more frequent.
Venous and Lymphatic Causes
When swelling persists in one or both legs without an obvious injury, two of the most common culprits are chronic venous insufficiency and lymphedema. They can look similar but have different mechanisms.
Chronic venous insufficiency happens when the valves inside your leg veins stop working properly. Blood that should be flowing back toward your heart pools in the lower legs, increasing pressure in the small vessels and forcing fluid out into the tissue. Up to 20 to 50 percent of people who’ve had a deep vein blood clot develop a related condition called postthrombotic syndrome, which can cause ongoing pain, swelling, and eventually fibrosis and leg ulcers.
Lymphedema, on the other hand, is a problem with the lymphatic drainage system itself. It can be something you’re born with (primary lymphedema) or something that develops after surgery, radiation, trauma, or infection damages the lymph vessels or nodes. The swelling tends to feel firmer and may not improve as much with elevation. Notably, all patients with significant venous insufficiency are now considered to have a lymphatic component as well, since the overloaded venous system eventually overwhelms the lymphatic system too.
When Swelling Signals an Organ Problem
Swelling that shows up in both legs, or in your legs along with your abdomen or face, can point to problems with your heart, kidneys, or liver. In heart failure, the heart can’t pump blood efficiently, which causes fluid to back up into the veins and leak into tissue. The body responds by retaining even more sodium and water, which makes the swelling worse. That retained fluid also increases pressure on the kidneys, reducing their ability to filter blood, which compounds the problem further.
Kidney disease can cause swelling through a different path: when the kidneys can’t excrete enough sodium or lose too much protein into the urine, fluid accumulates throughout the body. Liver disease, particularly cirrhosis, reduces production of albumin, the protein that helps keep fluid inside your blood vessels. Without enough of it, fluid seeps into the abdomen and legs.
A simple test you can do at home gives a rough sense of severity. Press your thumb firmly into the swollen area for a few seconds, then release. If it leaves a visible dent, that’s called pitting edema. A shallow 2mm pit that bounces back immediately is mild. A deep pit of 8mm or more that takes over 30 seconds to fill back in suggests significant fluid retention that needs medical evaluation.
Blood Clot Warning Signs
Swelling that appears suddenly in one leg, especially if it’s accompanied by pain, warmth, or redness, can signal a deep vein thrombosis (DVT), a blood clot in one of the deep veins. This is a medical emergency not because of the swelling itself but because of what can happen next: a piece of the clot can break loose and travel to the lungs, causing a pulmonary embolism.
Signs of a pulmonary embolism include sudden shortness of breath, chest pain that gets worse when you breathe in or cough, a rapid pulse, dizziness or fainting, and coughing up blood. If you have new one-sided leg swelling along with any of these symptoms, that warrants emergency care.
How Persistent Swelling Is Evaluated
When you see a doctor for swelling that won’t resolve, the first step is usually a physical exam and health history to narrow down whether the cause is local (vein or lymph issue in the affected area) or systemic (organ-related). If a systemic cause is suspected, blood and urine tests can check kidney function, liver enzymes, protein levels, and thyroid function, among other things.
For leg swelling specifically, a duplex ultrasound is typically the first and often only imaging test needed. It can reveal blood clots, damaged vein valves, and blood flow problems without any radiation or needles. If lymphedema is suspected and the ultrasound doesn’t tell the full story, a specialized imaging test called lymphoscintigraphy can map how well the lymphatic system is moving fluid from the feet upward.
The practical takeaway: swelling that follows a clear downward trend after an injury is your body doing its job. Swelling that plateaus, worsens, or appears without a clear cause is your body signaling that something in the drainage or production side of the equation isn’t working. The earlier that signal gets investigated, the more options exist to prevent the tissue damage, infections, and skin breakdown that come with months or years of unresolved fluid buildup.