Phentermine Mechanism of action

Phentermine works on the hypothalamus portion of the brain to release norepinephrine, a neurotransmitter or chemical messenger that signals a fight-or-flight response, reducing hunger. Phentermine works outside the brain as well to release epinephrine or adrenaline causing fat cells to break down stored fat, but the principal basis of efficacy is hunger-reduction. At clinically relevant doses, phentermine also releases serotonin and dopamine, but to a much lesser extent than that of norepinephrine.