How drug affect the body is called

The action of drugs on the human body is called pharmacodynamics, and what the body does with the drug is called pharmacokinetics. The drugs that enter the human tend to stimulate certain receptors, ion channels, act on enzymes or transporter proteins. As a result, they cause the human body to react in a specific way.

The effect of drugs on the body is called tolerance.

Explanation:

When people use drugs overtime, the effects do not "move" them like they first did. When people come to almost no effect with any drug means that their body is so use to it, their body adapts by tolerating the drug.