There could be many different reasons why you might take drugs or drink alcohol. This could be because you want to fit in with a group, or to join in with your friends. Perhaps you want to see what it's like. Or maybe you think it might help you deal with a difficult or stressful time.
These are complex issues but there are plenty of resources that can help you learn how drugs and alcohol can affect your mental health and what to do if you need support. If you're struggling with drugs or alcohol, then please talk to a trusted adult or your GP.
There is lots of excellent information on the YoungMinds website.
Please take a look at the Catch22 website too.
You can also find help and advice on the Royal College of Psychiatrists website.
And the NHS website also contains information which may help you.