Mild swelling in both legs at the end of a hot day is usually harmless. However, sudden swelling in just one leg, especially with pain and warmth, requires immediate medical evaluation due to the suspicion of deep vein thrombosis.
Swollen ankles and feet are a common occurrence during summer heat. Heat naturally dilates blood vessels, and prolonged sitting or standing makes it harder for blood to return to the heart, causing fluid to accumulate in the lower extremities. Such mild swelling, which typically affects both legs and subsides after rest or elevating the legs, is usually not a cause for concern.
The situation is different when swelling appears suddenly, is more pronounced than usual, lasts all day, and does not decrease even after elevating the leg. "That's not the kind of swelling we worry about," explained Dr. Michael Tran, a vascular medicine specialist, to the Cleveland Clinic. An additional alarming signal is new, unexplained pain resembling a severe cramp, especially in the calf.
Podiatrist Dr. Georgeanne Botek warns that typical fluid retention almost always affects both legs symmetrically. If you notice that only one side of your body is swelling, she advises seeking medical evaluation as soon as possible, precisely because of the possibility of deep vein thrombosis. Diagnosing the condition solely through visual inspection or palpation of the leg is not possible.
According to the UK's National Health Service (NHS), thrombosis most commonly causes throbbing or cramping pain in one leg, usually in the calf or thigh. Along with pain, there may be swelling, skin that is warm to the touch, redness or other discoloration, and hard, tender veins. It is important to note that some people have no visible symptoms at all.
The most dangerous complication occurs if part of the clot breaks off and travels through the bloodstream to the lungs, where it can cause a pulmonary embolism. If symptoms such as difficulty breathing, rapid or irregular heart rate, chest pain that worsens with deep breathing or coughing, coughing up blood, severe dizziness, or loss of consciousness occur, call emergency services immediately.
The likelihood of developing blood clots increases after surgical procedures, trauma, prolonged immobility, during pregnancy and after childbirth, with malignant diseases, a history of thrombosis, and after long trips without movement. Additionally, the use of contraceptives or hormone therapy containing estrogen can contribute to an increased risk. Although heat can cause leg swelling, the presence of warmth alone does not necessarily indicate a clot.
