The things you should avoid when taking a medication depends on the type of medication and why you are taking the medication.
If you are taking a drug that can make you feel drowsy you are adviced to stay at home, do not drive, do not operate any machine just stay home and rest. You are also adviced to avoid certain food when taking some medications.
According to a study, it is believed that banana can reduce blood pressure and blood sugar so it is adviced that you don't take banana if you are on blood pressure lowering drugs.
There are many other things you should avoid when taking medications. Ask your health care provider for more information on the medication you are taking.