Some medicines, particularly antibiotics, must be taken before food or on an empty stomach. This is because some food and drink can interact in negative ways with the medication, which would make it work less effectively to treat your infection. Though not all food or drink will do this, it is best to avoid eating to be on the safe side. Food and drink can also prevent your stomach from absorbing the medication entirely, so to make sure that you get the correct dose, an empty stomach is advisable.