Flagylmetronidazole
According to the FDA label: Symptomatic Trichomoniasis. Metronidazole tablets are indicated for the treatment of T. vaginalis infection in females and males when the presence of the trichomonad has been confirmed by appropriate laboratory procedures (wet smears and/or cultures). Asymptomatic Trichomoniasis. Metronidazole tablets are indicated in the treatment of asymptomatic T. vaginalis infection in females when the organism is associated with endocervicitis, cervicitis, or cervical erosion.
62,195 adverse event reports submitted to the FDA (1999–2026)
Top Reported Adverse Events
The most frequently reported events in association with Flagyl in the FAERS database. These are events reported by patients taking this medication, not necessarily caused by it. A single report may include multiple events.
Show these terms with plain-language definitions
Tap any term below for a plain-language definition.
Drug Ineffective 5,300 reports
A report that the medication did not work as expected for the person taking it. This is a reporting category, not a sign the drug is defective. It simply means someone felt it was not helping their condition.
Full definition in the glossary →Nausea 4,579 reports
The feeling of sickness in your stomach that often comes before vomiting.
Full definition in the glossary → See all drugs reporting this event →Off Label Use 4,032 reports
Using a medication for a condition or in a way that the FDA has not officially approved. This is common and often legal, and a report of it does not mean something went wrong. Doctors sometimes prescribe drugs off label based on their judgment.
Full definition in the glossary →Diarrhoea 4,004 reports
Loose or watery bowel movements, often frequent. Also spelled diarrhea in American English.
Full definition in the glossary → See all drugs reporting this event →Vomiting 3,221 reports
Throwing up the contents of the stomach.
Full definition in the glossary → See all drugs reporting this event →Pyrexia 3,166 reports
The medical term for fever, meaning a raised body temperature.
Full definition in the glossary → See all drugs reporting this event →Drug Hypersensitivity 3,115 reports
An allergic-type reaction to a medication.
Full definition in the glossary →Pain 2,979 reports
A general report of physical discomfort, used when no more specific location is given.
Full definition in the glossary →Abdominal Pain 2,914 reports
Pain in the belly or stomach area.
Full definition in the glossary → See all drugs reporting this event →Headache 2,777 reports
Pain in the head or upper neck.
Full definition in the glossary → See all drugs reporting this event →Fatigue 2,715 reports
Extreme tiredness or lack of energy that does not improve with rest.
Full definition in the glossary → See all drugs reporting this event →Dyspnoea 2,173 reports
Shortness of breath or difficulty breathing. Also spelled dyspnea in American English.
Full definition in the glossary → See all drugs reporting this event →Dizziness 2,128 reports
A feeling of being lightheaded, unsteady, or like the room is spinning.
Full definition in the glossary → See all drugs reporting this event →Condition Aggravated 2,069 reports
A report that the person's existing health condition got worse. This describes a worsening of something the person already had, not necessarily a new problem caused by the drug.
Full definition in the glossary →Malaise 1,967 reports
A general feeling of being unwell or uncomfortable, without a specific symptom.
Full definition in the glossary →
Ranked by frequency of reports, not severity. The most-reported event is not necessarily the most dangerous or the most common in patients taking this drug.
Who Is Reporting
Demographics of patients in FAERS reports that included this information. Not all reports include patient demographics.
By Sex
View reporter sex data as a table
| Sex | Reports |
|---|---|
| Female | 34,875 |
| Male | 21,406 |
| Unknown | 203 |
By Age Group
View age group data as a table
| Age group | Reports |
|---|---|
| 0-17 | 3,147 |
| 18-34 | 7,876 |
| 35-49 | 8,126 |
| 50-64 | 11,366 |
| 65-74 | 8,303 |
| 75+ | 6,658 |
This shows who filed reports, reflecting who takes this drug and who tends to report, not who is at greatest risk.
Reported Outcomes
Outcomes recorded in FAERS reports that included Flagyl. A single report may involve multiple reactions, each with a different outcome. These categories are defined by FDA reporting guidelines, not by PillSignal.
View outcome data as a table
| Outcome | Reports |
|---|---|
| Other Serious | 34,641 |
| Hospitalization | 26,553 |
| Non-Serious | 9,805 |
| Death | 6,745 |
| Life-Threatening | 5,124 |
| Disability | 2,402 |
Serious outcomes are far more likely to be reported than mild ones, so this overstates how often outcomes are serious. A recorded death does not mean the drug caused it.
Report Volume Over Time
Number of FAERS reports received per quarter for Flagyl. Changes in volume may reflect shifts in prescribing rates, media attention, or reporting behavior, not changes in the medication's safety profile.
View report trend as a table
| Year | Reports |
|---|---|
| 1999 | 2 |
| 2003 | 2 |
| 2004 | 768 |
| 2005 | 820 |
| 2006 | 873 |
| 2007 | 887 |
| 2008 | 767 |
| 2009 | 1,180 |
| 2010 | 1,431 |
| 2011 | 1,904 |
| 2012 | 2,383 |
| 2013 | 2,164 |
| 2014 | 2,426 |
| 2015 | 3,273 |
| 2016 | 3,756 |
| 2017 | 3,481 |
| 2018 | 5,261 |
| 2019 | 5,609 |
| 2020 | 4,733 |
| 2021 | 4,497 |
| 2022 | 3,970 |
| 2023 | 3,935 |
| 2024 | 3,578 |
| 2025 | 3,716 |
| 2026 (partial) | 779 |
The steep increase around 2004 reflects the FDA's move to electronic submission, not a change in this drug's safety. Trends track reporting volume, not risk.
Medications commonly reported with Flagyl
In FDA adverse event reports that mention Flagyl, these medications appeared most often in the same report.
- Ciprofloxacin (10,689 reports)
- Ciprofolxacin (7,895 reports)
- Acetaminophen (7,237 reports)
- Vancomycin (7,041 reports)
- Prednisone (6,964 reports)
This reflects co-occurrence in submitted reports, not evidence of drug interaction or combined risk. People often report several medications taken for the same condition or for unrelated reasons. Talk to a doctor or pharmacist about your specific medications.
Related Drugs
Other medications with similar adverse event profiles in FDA FAERS reports.
Data Source
This data is sourced from the FDA's Adverse Event Monitoring System (AEMS), formerly FAERS, via the OpenFDA API. PillSignal is not affiliated with the FDA.
View this data on the FDA website →Data last updated: June 2026