Various psychoactive substances can be grouped into different categories. There are different ways to categorize psychoactive substances. The different substances within the same category resemble each other in their mechanism of action, effects and withdrawals. Also, same general principles of management as well as treatment modalities are applicable to many psychoactive substances that belong to the same category. Although different substances even within the same category need not be the same and can differ from each other. Also, some of these can share characteristics with certain substances from other categories as well.