Flagyl is the brand name for the antibiotic medication metronidazole. It is commonly used to treat various bacterial and parasitic infections, including those affecting the stomach, skin, and reproductive system. Flagyl works by stopping the growth of bacteria and parasites, making it effective against conditions like bacterial vaginosis and trichomoniasis. Patients typically take Flagyl orally in pill form or may receive it intravenously in a hospital setting. It is important to complete the full course of treatment as prescribed by a healthcare provider to ensure the infection is fully cleared and to prevent antibiotic resistance.