An opioid is a class of drugs chemically similar to alkaloids found in opium poppies. Historically, these drugs have been used for pain management, but have a high potential for abuse. 

A hallucinogen is a group of drugs that alter a person's perception, thoughts, and feelings. Hallucinations are sensations and visions that seem real, though are not. Hallucinogens are commonly found in plants such as mushrooms and cacti, or are man-made. 

A stimulant is a drug used to increase activity in the Central Nervous System. This class of drugs can be in prescription or non-prescription form. These are sometimes prescribed for ADHD, sleep disorders, mood disorders, and asthma. These drugs are highly addictive.

These drugs are illicitly produced with the intent of developing substances that differ slightly from controlled substances in their chemical structure while retaining their pharmacological effects.  These substances are commonly known as designer drugs and fall under several drug categories.

A depressant is a medication prescribed for sleep difficulties, anxiety disorders, muscle spasms, and to prevent seizures. These can be highly addictive drugs. People abuse depressants to feel euphoria or to relieve other drugs side effects.

Even though some substances are not currently controlled by the Controlled Substances Act, they pose risks to individuals who abuse them.