I have a lot of pain and facial swelling from a root canal retreat. i was given penicillin v and metronidazole. when will the swelling go down?

Call your dentist: Typically it can take 24 hours for an antibiotic to take effect. If the swelling and or pain is severe and increasing the you should call the dentist and report this. It may be necessary to change the antibiotic or do. Another treatment to provide relief for you.

Give time: It usually takes 24-36 hours to notice results after starting a course of antibiotics. If there is no change after3-4 days contact the dentist who did the root canal or sooner if the swelling increases after 36 hours.

Finished or not ?: If the root canal was finished, then it should only take a few days. You may need a different antibiotic , or an incision and drainage. Retreats are only 50% successful according to the literature.

Typically 3-7 days: Most advanced dental infections will take at least 2-3 days for antibiotics to start to have a positive effect. Depending on the progression and nature of the infection, this can take longer. One way to "get the upper hand" is to have a dentist make an incision and drain the swelling and greatly reduce the bacterial load. Facial swellings should be monitored as they can become quite serious.