FCS is a rare inherited disorder characterized by severely elevated TG levels due to severe genetic compromise of intravascular LPL activity. Hypertriglyceridemia is refractory to fibrates and O3FAs, and many patients suffer from recurrent attacks of hypertriglyceridemic acute pancreatitis. Genetic testing and/or clinical algorithms distinguish FCS from MCS, which is much more common and less severe. Management requires a strict lifelong diet with <15% of daily calories from fat. Promising new therapies targeting APOC3, such as olezarsen and plozasiran, may help with long-term management of patients with FCS by reducing TG and pancreatitis risk.