It’s actually unlikely that drinking alcohol in moderation will cause a big problem if you’re taking a common antibiotic.
The main one that is a problem, however, is metronidazole, an antibiotic sometimes used for dental or vaginal infections, skin infections, infected leg ulcers and pressure sores. This has a severe interaction with alcohol, so not only do you need to avoid alcohol completely while taking it, but also continue to avoid alcohol for 48 hours after you stop taking it.