C. diff Risk


Oral Bioavailability


Approximate Cost


Cystitis Macrobid 100 mg PO BID

Nitrofurantoin should be avoided
CrCl Less Than 30 mL/min

100 mg PO BID
CrCl Greater Than 30 mL/min

General Information

Common Usage

Uncomplicated cystitis in females with normal renal function

Adverse Effects

Interstitial pneumonitis and fibrosis especially with prolonged use.

Peripheral neuropathy.

Major Interactions

Antacids decrease absorption

Additional Information

Think of this drug as a urinary antiseptic.

Not recommended in males due to inadequate tissue penetration, especially with possible occult prostatitis.


Antimicrobial class: Nitrofuran

Pregnancy category: B (Contraindicated at term)

Average serum half life: 1 hour

Biliary penetration: None

CSF penetration: None

Lung penetration: None

Urine penetration: Therapeutic