Flagyl strep throat. How to Diagnose Strep ThroatCan taking the antibiotic flagyl cause strep throat? ChaCha Answer: An antibiotic should not cause an infection. For a simple case of strep throat, Flagyl would not be the treatment of choice. BRAND NAME: Flagyl. Best Answer: If untreated, strep throat can lead to many serious complications. . . Ignoring this condition can result in other health problems. . Best Answer: Yeah metronidazole is a poor choice, it would probably have minimal effect, ... more