Macrobid is licensed to treat urinary tract infections (UTIs) -- in particular, those caused by Escherichia coli or Staphylococcus saprophyticus bacteria. The medicine is approved for use in people age 12 and up. Healthcare providers may occasionally recommend using Macrobid "off-label," such as prescribing it to prevent (instead of treat) UTIs.
Macrobid® (nitrofurantoin monohydrate/macrocrystalline) is a prescription antibiotic approved for the treatment of urinary tract infections (UTIs). Specifically, Macrobid is approved for treating bladder infections caused by Escherichia coli or Staphylococcus saprophyticus bacteria (the most common types of bacteria responsible for UTIs).
Macrobid is not approved to treat kidney infections.
Macrobid works in a unique way, compared to other antibiotics. In bacterial cells, the drug is changed into a highly reactive form that destroys certain bacterial proteins and molecules. As a result, the drug interferes with bacteria's ability to make essential cell components such as protein, DNA, and cell walls.
Macrobid contains two forms of nitrofurantoin. Seventy-five percent of the nitrofurantoin is in the monohydrate form and is mixed with a special powder. In the digestive tract, the powder and the nitrofurantoin monohydrate form a gel that releases the medication slowly over time. Twenty-five percent of the drug is in the macrocrystalline form (the same form in Macrodantin®, a similar antibiotic that must be taken four times a day, compared to just twice daily with Macrobid).
Macrobid is approved for use in individuals who are at least 12 years old. Other forms of nitrofurantoin (such as Macrodantin or Furadantin®) are more suitable for young children, as they are available in lower strengths.