What effect does drugs have on the endocrine and Immune systems?

Depends on the drugs to be honest. Long term taking of drugs can impair the bodies ability to use its immune system effectively. For example I was on Anti biotics for 6 months and I got so many colds I went to doctor and she said it was because my immune system was weak.

Some drugs do directly affect your endocrine system however if you look on the Internet something like netdoctor.co.uk they talk about drug interactions with your body.