Metronidazole: Uses, Side Effects, and What You Need to Know

When you hear metronidazole, a broad-spectrum antibiotic and antiprotozoal drug used to treat infections caused by anaerobic bacteria and certain parasites. Also known as Flagyl, it's one of the most prescribed drugs for stubborn infections that don't respond to regular antibiotics. It doesn't just kill bacteria—it targets the ones that thrive where oxygen is low, like deep abscesses, infected gums, or inside the gut. This makes it essential for conditions most other antibiotics can't touch.

Metronidazole works by breaking down the DNA of microbes that can't survive in oxygen-rich environments. That’s why it’s often paired with other drugs for mixed infections—like when a dental abscess has both aerobic and anaerobic bugs. It’s also a go-to for bacterial vaginosis, a common vaginal infection caused by an imbalance of normal bacteria, and trichomoniasis, a sexually transmitted protozoal infection. You’ll find it used for stomach ulcers linked to H. pylori, pelvic inflammatory disease, and even certain types of brain infections when other treatments fail.

But it’s not without trade-offs. Many people report a metallic taste in their mouth, nausea, or a dry mouth. The most talked-about side effect? Alcohol. Drinking while on metronidazole can cause flushing, rapid heartbeat, vomiting, and severe discomfort. It’s not just a warning—it’s a hard rule. Even products like mouthwash or hand sanitizer with alcohol can trigger reactions. Some users also report nerve-related issues like tingling or numbness, especially with long-term use. These aren’t common, but they’re serious enough to watch for.

It’s not a drug you take casually. Doctors usually prescribe it for short bursts—5 to 10 days—because the body doesn’t handle prolonged exposure well. It’s also not safe during early pregnancy unless the infection is life-threatening. And while it’s cheap and widely available, it’s not a cure-all. If your symptoms don’t improve after a few days, you might be dealing with something else entirely.

What you’ll find below is a collection of real-world guides and comparisons that dig into how metronidazole fits into broader treatment plans. You’ll see how it stacks up against other antibiotics, what to do if side effects hit hard, and how it’s used in conditions you might not expect—like skin infections or post-surgical care. These aren’t just drug facts. They’re practical stories from people who’ve used it, struggled with it, and learned how to make it work.