Swollen legs can be a sign of several different conditions, and the cause depends on how quickly it develops, whether it’s in one or both legs, and what other symptoms are present.
Most commonly, swelling in the legs is due to fluid buildup called edema.
Common causes of swollen legs
One frequent cause is poor circulation, especially from sitting or standing for long periods. Gravity causes fluid to collect in the lower legs and ankles.
Heart-related issues can also contribute. In conditions like Congestive heart failure, the heart doesn’t pump efficiently, which can cause fluid to back up in the legs.
Kidney problems may also lead to swelling because the body can’t properly remove excess fluid and salt. Similarly, liver disease can affect fluid balance and protein levels in the blood.
Blood clots are another important cause. A clot in a deep vein, known as Deep vein thrombosis, usually affects one leg and can be serious.
Other possible reasons
- Certain medications (like blood pressure drugs)
- Pregnancy
- Excess salt intake
- Injury or inflammation in the leg
When to be more concerned
Seek medical attention urgently if swelling:
- Is sudden or only in one leg
- Comes with pain, redness, or warmth
- Is accompanied by chest pain or shortness of breath
- Gets worse quickly
Bottom line
Swollen legs are a symptom, not a diagnosis. It can be something simple like fluid retention—or a sign of a more serious condition involving the heart, kidneys, or blood vessels.
If you want, tell me how long it’s been happening and whether it’s one leg or both, and I can help narrow down the most likely cause.
