Question: how many times a day should you take nitrofurantoin?
Answer: The usual dose of nitrofurantoin to treat a urinary tract infection is either 100mg taken twice a day or 50mg taken 4 times a day. Severe infections may need a higher dose of 100mg taken 4 times a day. The usual dose of nitrofurantoin to prevent a urinary tract infection is 50mg to 100mg once a day at night.