Side effects of taking metronidazole usually go away in 3 to 5 days. Side effects such as headache, nausea, and abnormal taste may occur after taking metronidazole, but recovery may take longer for patients with persistent peripheral neuropathy from long-term metronidazole use. Taking metronidazole may cause patients to experience a variety of side effects such as nausea, vomiting, loss of appetite, abdominal pain, diarrhea, metallic taste in the mouth, headache, dizziness, leukopenia, cystitis, and difficulty urinating, most of which can resolve on their own within 3 to 5 days after stopping the drug. However, some patients taking metronidazole for a long period of time may experience side effects such as numbness of limbs and abnormal sensation, which is caused by persistent peripheral neuropathy after taking the drug for a long period of time. In this case, it is necessary to stop taking the drug immediately and take drugs such as vitamin B6 and methylcobalamin, and can also be treated through rehabilitation training and other methods. If side effects occur after taking metronidazole, a doctor should be consulted and disposed of.