If you take a medicine in a way that is different from what the doctor prescribed, it is called prescription drug misuse. It could be
Misusing some prescription drugs can lead to addiction. These include opioids, sedatives, tranquilizers, and stimulants.
Every medicine has some risk of side effects. Doctors take this into account when prescribing medicines. People who misuse these drugs may not understand the risks. The medicines may not be safe for them, especially at higher doses or when taken with other medicines.
NIH: National Institute on Drug use disorder
Source: U.S National Library of Medicine (MedlinePlus)