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Metronidazole Side Effects
As is common with older medications, only vague side effect information is available for metronidazole. Based on this limited information, side effects of metronidazole may include headaches, dry mouth, and sore throat. In most cases, these problems are mild and do not require medical attention. However, you should contact your healthcare provider if you experience seizures, numbness in a limb, or an allergic reaction.
Just like any medicine, metronidazole (Flagyl®, MetroCream®, MetroGel®, MetroGel-Vaginal®, MetroLotion®, Noritate®, Vandazole®) can cause side effects. However, not everyone who takes the medication will have problems. In fact, some people tolerate it quite well. If side effects do occur, in many cases, they are minor and either require no treatment or can easily be treated by you or your healthcare provider.
(This article covers many, but not all, of the possible side effects with metronidazole. Your healthcare provider can discuss a more complete list of side effects with you.)
For many medications, the prescribing information carefully explains the exact percentage of side effects that were seen in clinical trials. However, the prescribing information for almost all older medications (including some metronidazole products) includes only vague side effect information, with no percentages provided. Therefore, it can be difficult to know exactly how common or how rare problems with such medications may be. In addition, the many different forms of metronidazole may have different side effects.
Some of the possible metronidazole side effects are thought to include:
- Headaches
- Vaginal irritation or infection
- Nausea, vomiting, or stomach pain
- Metallic taste in the mouth
- Bacterial infections
- Flu-like symptoms (such as a fever and chills)
- Genital itching
- Dizziness
- Diarrhea or constipation
- Runny or stuffy nose
- Sinus infection
- Sore throat
- Painful menstrual periods
- Vaginal yeast infections
- Dry mouth
- Urinary tract infection (UTI), such as a bladder infection.
Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD