Hi there
There are many different types of drugs and each one will have different effect on different people.
You can be prescribed drugs through a doctor for medical reasons and there are those drugs that are obtained illegally. These are the one's no one should take.
It would help you alot if you had a look at www.talktofrank.com this website provides an A-Z of drugs and their effects. It also provides help and support for young people.
You may want to come and talk to ChildLine about this issue and you can do this either by phone, online in a 1-2-1chat.
Hope this helps and hey take care
Sam