how long can macrobid last in your system
Top 10 Doctor insights on: How To Flush Macrobid Out Of System. 1 How long does Macrobid stay in your system after taking the last dosage? 24hours: Half life is 12 hours. That means the half of the total dose taken will be gone after 12 hours and then another 12 hours 50% from the other half will be gone and so forth.