Semaglutide and tirzepatide were first used to help type 2 diabetes patients regulate their blood-sugar levels.
But in the past three to four years, they started being prescribed as a weight-loss aide, leading to global shortages and counterfeit products.
Both are given as weekly injections via pre-filled pens self-administered into the upper arm, thigh or stomach.
And patients generally start on a low dose, which is gradually increased.
The drugs mimic the intestinal hormone glucagon-like peptide-1 (GLP-1), which is released after eating and typically makes people feel fuller.
Tirzepatide (Mounjaro) also affects the glucose-dependent insulinotropic polypeptide (GIP) hormone, which controls metabolism and helps regulate energy balance.
The first study into weight-loss drugs has found they can significantly improve heart health, with lower levels of heart attacks, stroke, heart failure and high blood pressure.
