Can you take penicillin and flagyl at the same time?

Yes, that would be OK. Remember to take all of your Flagyl even after you start feeling better. You want to kill all the bacteria and not leave any hiding in your body! Also remember that Flagyl is the antibiotic which has a severe reaction with alcohol. Do not drink any alcohol while taking this, and check the ingredient labels of any liquids you put into your mouth or onto your skin. If it has alcohol as an ingredient, stay away from it.