Generic Macrobid

Common use

Macrobid is a wide spectrum antibiotic. It inhibits construction of a bacterial cell wall, synthesis of a bacterial DNA and RNA, proteins, inhibits aerobic metabolism. This medication is used to treat bacterial infections of the urinary tract caused by E. Coli, Enterobacter cystitis, Staphylococcus aureus, and Enterococcus, Klebsiella such as pyelitis, pyelonephritis, cystitis, urethritis, to prevent infections during urological surgeries, cystoscopy, catheterization. Macrobid is a sustained release macrocrystalline form of the antibiotic. Nitrofuranton is also available in a microcrystalline form (Furadantin), and a macrocrystalline form (Macrodantin). Absorption of the medication depends on the size of crystals and presence of food in the gastrointestinal tract.



Dosage and directions

Take 100 mg of Macrobid every 12 hours. Taking with a meal or milk increase its absorption and helps to avoid your stomach upset. Usual course of treatment continues seven days. Follow all recommendations of your doctor. Do not stop or start this medication without your doctor's permission.



Precautions

Before to take Macrobid inform your doctor if you have kidney disease, anemia, diabetes, an electrolyte imbalance, glucose-6-phosphate dehydrogenase (G6PD) deficiency, vitamin B deficiency, any type of debilitating disease. This medication can change results of urine glucose tests. This medication may cause diarrhea, if you have watery or bloody stools inform your doctor about. Do not take any antidiarrhea medication unless it was administered to you as diarrhea may be a sign of a new infection.



Contraindications

Macrobid cannot be used in patients with kidney or liver failure, jaundice in history, glucose-6-phosphate dehydrogenase deficiency, acute porphyria, pregnancy, in children under 12 years of age. Breastfeeding should be interrupted when on Macrobid.



Possible side effect

The most common adverse reactions are headache, dizziness, drowsiness, allergic reactions (rash, itching), nausea, vomiting. In rare cases diarrhea, loss of appetite, pseudomembranous colitis, and abdominal pain may occur.



Drug interaction

High doses of probenecid (Benemid) or sulfinpyrazone (Anturane) can inhibit secretion by kidney channels and decrease urine levels of Macrobid. Consequently blood concentrations of Macrobid increases as well as the risk of toxicity. Antibacteral effect of Macrobid is reduced by nalidixic acid, while is absorption is decreased by antacids which contain magnesium trisilicate. Co-administration with quinolone antibiotics such as norfloxacin (Noroxin) reduces their effects.



Missed dose

If you miss a dose, take it as soon as you remember unless it is almost time of your next dose. If it is near the time of the next dose, skip the missed dose and return dosing schedule. Do not double the dose to make up the missed dose.



Overdose

Symptoms of overdose include nausea or vomiting. If you suppose that too much of Macrobid was taken seek immediate medical attention.



Storage

Store at room temperature in a tight container, away from moisture and humidity.



Disclaimer

We provide only general information about medications which does not cover all directions, possible drug integrations, or precautions. Information at the site cannot be used for self-treatment and self-diagnosis. Any specific instructions for a particular patient should be agreed with your health care adviser or doctor in charge of the case. We disclaim reliability of this information and mistakes it could contain. We are not responsible for any direct, indirect, special or other indirect damage as a result of any use of the information on this site and also for consequences of self-treatment.

Clinical Verification

Last Clinically Updated: August 15, 2026

Written By

Dr. Elena Vance, PharmD

Clinical Specialist in Neuropharmacology

Fact Checked By

Marcus Thorne, MS

Biomedical Data & FDA Label Verification

Medically Reviewed By

Dr. Arthur Campbell, MD

Board-Certified Psychiatrist (ABPN)