Drinking alcohol while using Flagyl can lead to cramps, headaches, face redness, vomiting and abdominal pain. The United States Centers for Disease Control and Prevention states that drinking alcohol 24 hours after using Flagyl has numerous side effects, as noted by Healthline.
If a person has had issues of alcohol addiction before, it is necessary to consult prior to using Flagyl. Combination of alcohol and Flagyl can lead to changes in blood pressure, liver damage and increased heart rate. Also, the use alcohol during medication can cause a person to skip his or her doses. When used alone, Flagyl has some side effects, such as dry mouth, diarrhea and discolored urine, as stated by Healthline.