Nitrofurantoin Oral Suspension
(Common brand name: Macrobid S, Macrodantin S, Nitrofurantoin S, etc.)
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What is it for?
Nitrofurantoin is an antibiotic that specifically treats uncomplicated urinary tract infections (UTIs) caused by susceptible bacteria (most commonly Escherichia coli, Klebsiella, Proteus, Enterobacter, and Streptococcus species).
Because it concentrates in the urine, it’s most useful for lower‑tract infections (cystitis) and less effective for kidney or upper‑tract infections.
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How is it given?
- Form: Oral suspension (typically 5 mg/mL or 10 mg/mL).
- Typical adult dose: 50 mg every 6 h (200 mg total per day) for 5–7 days for cystitis; for pyelonephritis, 100 mg every 12 h for 10–14 days.
- Children: Weight‑based dosing (0.7 mg/kg every 8 h).
- Administration: Shake well before each dose. The dose is usually divided into 3–4 equal portions throughout the day.
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How to take it
| Step | What to do | Why |
|------|------------|-----|
| Shake | Shake the bottle vigorously for 20–30 s. | Ensures even distribution of the drug in the suspension. |
| Measure | Use the provided syringe or cup. | Accurate dosing is essential for effectiveness and safety. |
| Take with food | Preferably after a meal or a snack. | Reduces stomach upset; improves absorption. |
| Finish the full course | Even if symptoms improve earlier. | Prevents relapse and reduces resistance. |
| Do not split tablets | (Only use the suspension if prescribed that form). | Tablets may not provide accurate dosing when broken. |
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What to watch for (Common side effects)
- Gastro‑intestinal: Nausea, vomiting, loss of appetite, abdominal pain, diarrhea.
- Allergic reactions: Rash, itching, urticaria, angioedema; severe reactions are rare but possible.
- Rare but serious: Pulmonary inflammation, liver enzyme elevations, neuropathy with prolonged use (>6 weeks), bone marrow suppression (anemia, leukopenia, thrombocytopenia).
If you notice breathing difficulties, chest pain, persistent cough, jaundice, or unexplained fatigue, contact your health provider promptly.
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When to avoid or use cautiously
| Situation | Reason | What to do |
|-----------|--------|------------|
| Renal impairment (CrCl < 30 mL/min) | Nitrofurantoin is excreted by kidneys; inadequate filtration reduces drug clearance and increases toxicity. | Generally not recommended; alternative agents (e.g., fosfomycin, pivmecillinam) may be preferred. |
| Pregnancy (especially 3rd trimester) | Potential fetal exposure; data are limited but concerns exist. | Avoid unless absolutely necessary; discuss alternatives with your provider. |
| Children < 2 months | Limited safety data; higher risk of toxicity. | Avoid. |
| Severe hepatic disease | Metabolites may accumulate. | Use with caution; monitor liver enzymes. |
| History of neuropathy | Can worsen nerve damage. | Monitor symptoms; consider alternative antibiotic. |
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Drug interactions
- Antacids or sucralfate: May reduce absorption. Take these at least 2 h before or after the dose.
- Metformin: Rarely, nitrofurantoin can increase metformin levels, raising the risk of lactic acidosis. Check kidney function and monitor.
- Cimetidine, ranitidine: May increase plasma concentration. Adjust dose if needed.
- Other antibiotics: No major interactions, but be mindful of overlapping nephrotoxicity if combined with other renal‑excreted drugs.
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Storage
- Store at room temperature (≤25 °C / 77 °F), away from light and moisture.
- Keep the lid tightly closed.
- Do not freeze.
- Discard any unused medication after the expiration date or after 14 days if it has been opened (check the label; many formulations have a “use within 7–14 days” instruction once opened).
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How to tell your pharmacist or prescriber if it’s not working
- Symptoms persist after 3–4 days: Consider drug resistance or a different diagnosis (e.g., pyelonephritis, stones, prostatitis).
- New or worsening pain: Could indicate an evolving infection.
- Side effects that interfere with adherence: Discuss alternative dosing or a different agent.
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Quick “Take‑Home” Checklist for Patients
1. Shake the bottle before each dose.
2. Measure with the supplied syringe.
3. Take with food (or a snack).
4. Complete the full course.
5. Watch for nausea, rash, shortness of breath, or changes in urine color.
6. Call your doctor if you have fever, chills, flank pain, or persistent symptoms.
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FAQs
Q1: Can I use nitrofurantoin if I’m on dialysis?
A1: Typically, it’s not recommended because the drug is renally cleared and may accumulate. Your nephrologist may advise a different antibiotic.
Q2: Why is my prescription a suspension instead of a tablet?
A2: For children or patients who have difficulty swallowing pills, the liquid formulation allows for accurate, weight‑based dosing.
Q3: Is it safe to take with other medications?
A3: Generally, yes, but be mindful of antacids, metformin, and cimetidine. Always inform your prescriber of all medications you’re taking.
Q4: Can I drink alcohol while taking nitrofurantoin?
A4: Moderate alcohol is usually fine, but it can increase the risk of GI upset. If you experience nausea or stomach discomfort, consider limiting alcohol until the course is finished.
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Bottom Line
Nitrofurantoin oral suspension is a narrow‑spectrum, urine‑concentrated antibiotic that’s highly effective for uncomplicated cystitis when the causative bacteria are susceptible. Follow the dosing schedule closely, take it with food, and monitor for any side effects. If you have kidney problems, pregnancy, or any concerning symptoms, discuss alternatives with your health care provider.