What and who should be involved in addiction treatments like heroin detoxification for it to be successful?

I happen to have a cousin who is planning to undergo such treatment. Please help me.

Addiction treatment is a serious business. While you may get some useful answers from helpful people in a place like this, you need to check with medically qualified and experienced people.

You may find some help at Wikipedia – it may help point you to other places.

Laws are different in different parts of the world too.

Contact your local governmental health dept – or a local hospital.

Personal support is usually considered a good thing, if those people are not involved in the drug scene themselves – those who have 'dried out' often are helpful as they have been thru it themselves. There are many 'help organizations' of varying quality around – some even take the line of using 'Religion', Some ex-addicts as support.

Some treatments use just abstinence, while some methods use 'replacement drugs', some use a combination of approaches.

All methods do have a percentage failure rate – some people go thru the process more than once before they finally can stop falling back.