Drug combinations and their use are disclosed. A first drug is administered in combination with a second drug. The first drug such as fenfluramine is characterized by the formation of a metabolite including 5-HT2B agonists such as norfenfluramine with known adverse side effects. The second drug is in the form of a CYP inhibitor such as cannabidiol which modulates the formation of metabolite down thereby making the first drug safer.
