As J_9 said
Again, it is all about education of the particular illness involved. What to expect regarding side-effects of medications....how long to take the meds, etc.
There are things you can do but it depends on what you are taking what medicines for and
So forth. Many people try alternative herbs, vitamins and minerals but you have to know what ones work with your meds and what ones work against them and what ones accelerate the effect. So you should ask your doc to work with you if you want to go the alternative route.
For example, some people can take chromium picolinate for diabetes but they need to keep their levels monitored all the more cause you usually need less insolin.
When you take statin drugs for cholestrol you should take omega and Q 10.
If you look that up on the internet you will see that many doctors are saying it is important.
Also as J_9 said you have to take the whole script for antibiotics, but once you are through with it it is important to take probiotics or eat yogurt to replace healthy bacteria that your body needs.
I have been doing the alternative supplements and nutrition for preventative measures. Many people my age are already getting put on so many meds they look like a walking pharmacy. I spent the past 10 years teaching myself the alternative stuff and I am healthier than I was in my 20's (30 years ago!)