so if someone is on antibiotics, and tomorrow..enter 24 hours..he wants to drink..

will it have a negatice effect with the antibiotic..how long must one wait???
Depends on the antibiotic. If it says avoid alcohol on the leaflet inside the box, or on the box, or on the printed label from the chemist, then avoid alcohol, because you will probably be vom-tastic.
Read the leaflet that came with them. Most antibiotics you are all right to drink with, though still check to make sure. If you really want to be safe, phone your doctor.