Phentermine, like many other prescription drugs, works with chemicals called neurotransmitters in your brain. It actually stimulates your neuron bundles to release a particular group of neurotransmitters known as catecholamines, these include dopamine, epinephrine (formally known as adrenalin), and norepinephrine (noradrenalin).

These neurotransmitters signal a fight or flight response in your body which, in turn, puts a halt to the hunger signal. As a result, you lose your appetite because your brain doesn