Antibiotics Home > Macrobid

A long-acting medication, Macrobid is an antibiotic used for the treatment of urinary tract infections. The medicine works by destroying certain proteins and molecules within bacterial cells. It comes in the form of a capsule and is typically taken twice a day, with 12 hours between doses. Possible side effects include nausea, flatulence, and headache.

What Is Macrobid?

Macrobid® (nitrofurantoin monohydrate/macrocrystalline) is a prescription antibiotic approved to treat urinary tract infections (UTIs). It is a long-acting medication that is taken just twice a day.
(Click Macrobid Uses for more information, including possible off-label uses.)

Who Makes It?

Currently, brand-name Macrobid is made by Norwich Pharmaceuticals, Inc., for Procter & Gamble Pharmaceuticals, Inc. Generic versions are made by various manufacturers.

How Does Macrobid Work?

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).
Written by/reviewed by:
Last reviewed by: Kristi Monson, PharmD;
Last updated/reviewed:
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