Trust me I am a professional pharmacist. My license is enclosed in this post.
Some drugs are potentially very unsafe with alcohol and one must avoid alcohol while on medication of the following drugs.
1) Cholesterol-lowering drugs.: These drugs can give unnoticeable damage to the liver much more than the quantity of alcohol consumed.
2)Blood pressure and heart drugs: There can be a severe change in blood pressure and the heart rate leading to emergencies.
3) Birth control pills.: The effectiveness of the birth pills decrease on consumption of alcohol.
4) Anti-depression and tranquilizers: Consumption of alcohol can cause serious damage to the brain with these medications.
So above listed was some medications with which you must avoid alcohol completely.