Early signs and symptoms of systemic capillary leak syndrome (SCLS) can be similar to those of a common cold, involving nasal congestion, runny nose or a cough. This may progress to lightheadedness, weakness, fatigue, nausea, and sudden swelling (edema) of the arms, legs and other parts of the body. Fluid may collect around the heart, lungs and muscles, causing a potentially dangerous situation. Fainting can occur due to a rapid drop in blood pressure from fluid leakage.
SCLS doesn't appear to be inherited. The causes are unknown, but one possibility includes the presence of a chemical that damages or temporarily separates the cells lining the capillary walls, making them leak fluid. Treatment may control the disorder for weeks or even years, but primary SCLS is unlikely to be completely cured. A long-term (chronic), less intense form of SCLS can cause frequent symptoms.