Nitrofurantoin Is an Antibiotic Used to Treat and Prevent Urinary Tract Infections (UTIs)

Nitrofurantoin is a prescription antibiotic that has been a go-to treatment for uncomplicated urinary tract infections for over 70 years. If your doctor just prescribed it—or if you're trying to understand what it is before your appointment—this guide covers everything you need to know: what it treats, how to take it, who should avoid it, and what it costs in 2026.

What Is Nitrofurantoin?

Nitrofurantoin is a nitrofuran-class antibiotic that works specifically in the urinary tract. Unlike broad-spectrum antibiotics that affect bacteria throughout your body, Nitrofurantoin concentrates in your urine, targeting bacteria right where the infection is.

It's available under several brand names:

• Macrobid — The most commonly prescribed form (100 mg capsules containing monohydrate/macrocrystals)
• Macrodantin — Available in 25 mg, 50 mg, and 100 mg capsules (macrocrystalline form)
• Furadantin — An oral suspension (liquid) at 25 mg/5 mL, useful for patients who can't swallow capsules

Both Macrobid and Macrodantin are manufactured by Almatica Pharma (formerly Allergan/AbbVie), and generic versions are widely available from multiple manufacturers.

Nitrofurantoin is not a controlled substance and does not require any special prescribing authority.

What Is Nitrofurantoin Used For?

Nitrofurantoin has two FDA-approved uses:

1. Treatment of uncomplicated lower urinary tract infections (acute cystitis). This is the most common use—treating a straightforward bladder infection caused by susceptible bacteria like E. coli.
2. Prophylaxis (prevention) of recurrent urinary tract infections. For people who get frequent UTIs, a low dose of Nitrofurantoin taken daily at bedtime can significantly reduce the number of infections.

Nitrofurantoin is only effective for lower UTIs (bladder infections). It does not reach high enough concentrations in the blood or kidney tissue to treat upper UTIs (kidney infections/pyelonephritis) or infections elsewhere in the body.

Why doctors choose it: Nitrofurantoin has remarkably low resistance rates compared to other UTI antibiotics. While about 20% or more of E. coli strains are resistant to Trimethoprim-Sulfamethoxazole (Bactrim), resistance to Nitrofurantoin remains under 5% in most areas. This makes it a reliable first-line choice.

How Is Nitrofurantoin Taken?

For Treating an Active UTI

• Macrobid: 100 mg by mouth, twice daily for 5–7 days
• Macrodantin: 50–100 mg by mouth, four times daily for 7 days

For Preventing Recurrent UTIs

• 50–100 mg once daily at bedtime (long-term prophylaxis)

Important Dosing Tips

• Always take with food or milk. This increases absorption by approximately 40% and reduces nausea—the most common side effect.
• Complete the full course. Even if symptoms improve after 1–2 days, finish all prescribed doses. Stopping early can allow the infection to return and may contribute to antibiotic resistance.
• Swallow capsules whole. Do not crush or chew them.
• Shake the suspension well before measuring each dose if using the liquid form.

Who Should Not Take Nitrofurantoin?

Nitrofurantoin is not appropriate for everyone. Your doctor should not prescribe it if you have:

• Significant kidney impairment — Creatinine clearance below 60 mL/min. The drug won't concentrate in your urine effectively, and blood levels will rise to potentially toxic levels.
• Anuria or oliguria — Very low or no urine output.
• Known allergy to Nitrofurantoin — Previous hypersensitivity reaction.
• History of liver problems from Nitrofurantoin — Prior cholestatic jaundice or hepatic dysfunction linked to the drug.
• Pregnancy at term (38–42 weeks) — Risk of hemolytic anemia in the newborn. Nitrofurantoin is generally considered safe earlier in pregnancy.
• Infants under 1 month of age — Risk of hemolytic anemia.
• G6PD deficiency — A genetic enzyme deficiency that increases the risk of hemolytic anemia. This is a relative contraindication.

Additionally, older adults (65+) should use Nitrofurantoin with caution. It's on the Beers Criteria list of potentially inappropriate medications for seniors due to increased risks of lung toxicity, liver damage, and nerve damage.

How Much Does Nitrofurantoin Cost?

One of the advantages of Nitrofurantoin is that it's affordable, especially as a generic:

• With insurance: Most plans cover generic Nitrofurantoin as a Tier 1 (preferred generic) medication. Copays are typically $0–$15. No prior authorization or step therapy is usually required.
• With a discount coupon (no insurance): GoodRx, SingleCare, and other coupon programs bring the price down to $3–$10 for a typical course. Check our savings guide for more options.
• Cash price (no coupon, no insurance): Approximately $43 on average at retail pharmacies.
• Brand-name Macrobid: Can cost $200 or more without insurance. There's typically no clinical reason to pay for brand over generic.

Nitrofurantoin is covered by Medicare Part D and virtually all commercial insurance plans.

Final Thoughts

Nitrofurantoin is a time-tested, effective, and affordable antibiotic for uncomplicated UTIs. It has some of the lowest resistance rates of any UTI antibiotic, it's easy to take, and a full course costs less than a fast-food meal with a discount coupon. Just remember: take it with food, finish the whole course, and talk to your doctor about any kidney issues or allergies before starting.

If you have a prescription and need to find a pharmacy with Nitrofurantoin in stock, Medfinder can help. Or if you need to find a doctor who can prescribe it, we've got a guide for that too.