As a lifelong devotee of fermented malt beverages it pains me to say that this is not a great idea. Why? Because:
- All drugs are poisons
- Alcohol is also a poison
Mixing two poisons is never going to lead to a good outcome. More specifically, the same enzymes that break down alcohol in the liver often either clear or activate drugs, antibiotics included.
That said, the risk of mixing alcohol with antibiotics is not so great. Antibiotics as a drug class are very well tolerated, as are moderate amounts of alcohol. There is some risk that antibiotics will slow down the metabolism of alcohol (and vice versa) and this risk is elevated in people whose livers are damaged by excessive alcohol consumption. The main risk though, is for headaches, nausea and sweating. Here are the antibiotics most likely to cause these reactions:
From Harmful Interactions: Mixing Alcohol with Medicines
The antibiotic-alcohol interactions you really have to watch out for are isoniazid (risk of liver damage) and metronidazole (violent barfing).
I can attest personally to the latter. While on a course of metronidazole my daughter thoughtfully made me a smoothie. She added a splash of vanilla to give it a nice top note of flavor, just as I had taught her. Vanilla is extracted in ethanol. Fifteen minutes later I was retching so violently I thought I was going to vomit out my stomach.
So don’t do that.
Overall, you will probably make yourself feel worse, not better, if you drink beer while on antibiotics. But with few exceptions, you are quite unlikely to genuinely damage your health.