Macrodantin 50mg Capsules
It is used to treat or prevent a urinary tract infection (UTI).
Drug Class
Anti-infective, Urinary Tract Agent
Pharmacologic Class
Nitrofuran Antibiotic
Pregnancy Category
Category B (Contraindicated at term)
FDA Approved
Aug 2025
DEA Schedule
Not Controlled
Overview
What is this medicine?
Nitrofurantoin is an antibiotic used to treat and prevent urinary tract infections (UTIs). It works by stopping the growth of bacteria in the urine. It's important to take this medicine exactly as prescribed, usually with food, to help it work best and reduce stomach upset.
How to Use This Medicine
Taking Your Medication Correctly
To get the most benefit from your medication, follow your doctor's instructions carefully. Read all the information provided with your prescription and follow the instructions closely. Take your medication with food to help your body absorb it properly. Continue taking your medication as directed by your doctor or healthcare provider, even if you start to feel better.
It's also important to stay hydrated by drinking plenty of non-caffeinated liquids, unless your doctor advises you to limit your fluid intake. However, do not take antacids that contain magnesium trisilicate while taking this medication, as they may interact with it.
Storing and Disposing of Your Medication
To keep your medication effective and safe, store it at room temperature in a dry place, away from the bathroom. Keep all medications out of the reach of children and pets to avoid accidents. When you're finished with your medication or it expires, dispose of it properly. Do not flush it down the toilet or pour it down the drain unless instructed to do so by your doctor or pharmacist. If you're unsure about how to dispose of your medication, ask your pharmacist for guidance. You may also want to check if there are any drug take-back programs in your area.
What to Do If You Miss a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
To get the most benefit from your medication, follow your doctor's instructions carefully. Read all the information provided with your prescription and follow the instructions closely. Take your medication with food to help your body absorb it properly. Continue taking your medication as directed by your doctor or healthcare provider, even if you start to feel better.
It's also important to stay hydrated by drinking plenty of non-caffeinated liquids, unless your doctor advises you to limit your fluid intake. However, do not take antacids that contain magnesium trisilicate while taking this medication, as they may interact with it.
Storing and Disposing of Your Medication
To keep your medication effective and safe, store it at room temperature in a dry place, away from the bathroom. Keep all medications out of the reach of children and pets to avoid accidents. When you're finished with your medication or it expires, dispose of it properly. Do not flush it down the toilet or pour it down the drain unless instructed to do so by your doctor or pharmacist. If you're unsure about how to dispose of your medication, ask your pharmacist for guidance. You may also want to check if there are any drug take-back programs in your area.
What to Do If You Miss a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
Lifestyle & Tips
- Take with food or milk to improve absorption and reduce stomach upset.
- Drink plenty of fluids to help flush out bacteria and maintain good kidney function.
- Complete the entire course of medication, even if symptoms improve, to prevent the infection from returning and to reduce the risk of antibiotic resistance.
- Avoid antacids containing magnesium trisilicate, as they can reduce the effectiveness of nitrofurantoin.
Available Forms & Alternatives
Available Strengths:
Generic Alternatives:
Dosing & Administration
Adult Dosing
Standard Dose:
50-100 mg orally four times a day for 7 days (for acute uncomplicated UTI); 50-100 mg orally once daily at bedtime (for prophylaxis)
Dose Range:
50 - 100 mg
Condition-Specific Dosing:
acuteUncomplicatedUTI:
50-100 mg orally four times a day for 7 days
UTIProphylaxis:
50-100 mg orally once daily at bedtime
Pediatric Dosing
Neonatal:
Contraindicated in infants less than 1 month of age due to risk of hemolytic anemia.
Infant:
Contraindicated in infants less than 1 month of age. For infants >1 month, 5-7 mg/kg/day orally in 4 divided doses (max 400 mg/day).
Child:
5-7 mg/kg/day orally in 4 divided doses (max 400 mg/day) for acute infections; 1-2 mg/kg/day orally once daily at bedtime for prophylaxis.
Adolescent:
50-100 mg orally four times a day for 7 days (for acute uncomplicated UTI); 50-100 mg orally once daily at bedtime (for prophylaxis).
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment needed if CrCl > 60 mL/min.
Moderate:
Contraindicated if CrCl < 60 mL/min due to decreased efficacy and increased risk of toxicity (e.g., peripheral neuropathy).
Severe:
Contraindicated if CrCl < 60 mL/min.
Dialysis:
Contraindicated. Ineffective and increases risk of toxicity.
Hepatic Impairment:
Mild:
No specific adjustment recommended, but use with caution.
Moderate:
Use with caution; monitor for signs of hepatotoxicity.
Severe:
Use with caution; monitor for signs of hepatotoxicity. Contraindicated in patients with a history of cholestatic jaundice/hepatic dysfunction associated with nitrofurantoin.
Pharmacology
Mechanism of Action
Nitrofurantoin is reduced by bacterial flavoproteins to reactive intermediates that inactivate or alter bacterial ribosomal proteins, DNA, RNA, and other metabolic enzymes. These reactions lead to inhibition of bacterial cell wall synthesis, protein synthesis, aerobic respiration, and the Kreb's cycle. The broad-spectrum activity is due to multiple targets, which also minimizes the development of resistance.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 40-50% (macro-crystalline form), enhanced by food.
Tmax:
Approximately 4 hours (macro-crystalline form).
FoodEffect:
Absorption is significantly increased and prolonged when taken with food, which also helps reduce gastrointestinal upset.
Distribution:
Vd:
Not readily available, but widely distributed in body tissues, except for the CNS. Concentrates in urine.
ProteinBinding:
Approximately 60%.
CnssPenetration:
Limited
Elimination:
HalfLife:
0.3-1 hour (plasma half-life).
Clearance:
Rapid renal excretion.
ExcretionRoute:
Primarily renal (glomerular filtration and tubular secretion).
Unchanged:
Approximately 40-50% of the dose is excreted unchanged in the urine within 24 hours (macro-crystalline form).
Pharmacodynamics
OnsetOfAction:
Rapid, urinary concentrations achieved within 30 minutes.
PeakEffect:
Urinary concentrations peak within 4 hours.
DurationOfAction:
Effective urinary concentrations maintained for several hours, requiring multiple daily doses.
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention immediately:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Rarely, allergic reactions can be fatal.
Signs of pancreatitis (pancreas problem), such as:
+ Severe stomach pain
+ Severe back pain
+ Severe upset stomach or vomiting
Signs of lupus, such as:
+ Rash on the cheeks or other body parts
+ Easy sunburn
+ Muscle or joint pain
+ Chest pain or shortness of breath
+ Swelling in the arms or legs
Inability to control eye movements
Diarrhea, especially if it is severe or accompanied by:
+ Stomach pain
+ Cramps
+ Loose, watery, or bloody stools
+ Note: Diarrhea is common with antibiotics, but rarely, a severe form called C. diff-associated diarrhea (CDAD) can occur, which may lead to a life-threatening bowel problem.
Liver problems, which can be rare but potentially fatal, characterized by:
+ Dark urine
+ Tiredness
+ Decreased appetite
+ Upset stomach or stomach pain
+ Light-colored stools
+ Vomiting
+ Yellow skin or eyes
Nerve problems, which can be severe, persistent, or even fatal, especially in people with:
+ Kidney problems
+ Anemia
+ Diabetes
+ Electrolyte problems
+ Low vitamin B levels
+ Symptoms may include:
- Burning sensation
- Numbness
- Tingling that is not normal
Other Possible Side Effects
Most people do not experience significant side effects, but some may occur. If you notice any of the following side effects or if they bother you or persist, contact your doctor:
Headache
Upset stomach or vomiting
Decreased appetite
Stomach pain or diarrhea
Dizziness, drowsiness, tiredness, or weakness
Hair loss (which may be reversible after stopping the medication)
* Urine color change to brown (a harmless side effect)
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects. If you have questions or concerns, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention immediately:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Rarely, allergic reactions can be fatal.
Signs of pancreatitis (pancreas problem), such as:
+ Severe stomach pain
+ Severe back pain
+ Severe upset stomach or vomiting
Signs of lupus, such as:
+ Rash on the cheeks or other body parts
+ Easy sunburn
+ Muscle or joint pain
+ Chest pain or shortness of breath
+ Swelling in the arms or legs
Inability to control eye movements
Diarrhea, especially if it is severe or accompanied by:
+ Stomach pain
+ Cramps
+ Loose, watery, or bloody stools
+ Note: Diarrhea is common with antibiotics, but rarely, a severe form called C. diff-associated diarrhea (CDAD) can occur, which may lead to a life-threatening bowel problem.
Liver problems, which can be rare but potentially fatal, characterized by:
+ Dark urine
+ Tiredness
+ Decreased appetite
+ Upset stomach or stomach pain
+ Light-colored stools
+ Vomiting
+ Yellow skin or eyes
Nerve problems, which can be severe, persistent, or even fatal, especially in people with:
+ Kidney problems
+ Anemia
+ Diabetes
+ Electrolyte problems
+ Low vitamin B levels
+ Symptoms may include:
- Burning sensation
- Numbness
- Tingling that is not normal
Other Possible Side Effects
Most people do not experience significant side effects, but some may occur. If you notice any of the following side effects or if they bother you or persist, contact your doctor:
Headache
Upset stomach or vomiting
Decreased appetite
Stomach pain or diarrhea
Dizziness, drowsiness, tiredness, or weakness
Hair loss (which may be reversible after stopping the medication)
* Urine color change to brown (a harmless side effect)
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects. If you have questions or concerns, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Sudden onset of cough, shortness of breath, or chest pain (signs of lung problems).
- Unusual tiredness, nausea, vomiting, dark urine, yellowing of skin or eyes (signs of liver problems).
- Numbness, tingling, or weakness in your hands or feet (signs of nerve damage).
- Severe diarrhea that is watery or bloody (signs of a serious bowel infection).
- Fever, chills, body aches, sore throat, or unusual bleeding/bruising (signs of blood problems).
- Severe allergic reactions like rash, itching, swelling of face/tongue/throat, severe dizziness, trouble breathing.
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following conditions before starting this medication:
Any allergies you have, including allergies to this drug, its components, or other substances, such as foods or medications. Be sure to describe the symptoms you experienced.
Kidney disease, as this may affect how your body processes the medication.
Difficulty urinating, as this could be a sign of an underlying condition that may interact with the medication.
Previous liver problems caused by this medication, as this may increase your risk of further liver damage.
Pregnancy, particularly if you are 38 weeks or more pregnant, as this medication may affect the fetus.
Special Considerations for Children:
If the patient is a child under 1 month of age, do not administer this medication, as its safety and efficacy have not been established in this age group.
Additional Important Information:
This medication may interact with other medications, including prescription and over-the-counter drugs, natural products, and vitamins. Therefore, it is crucial to provide your doctor and pharmacist with a comprehensive list of all your medications and health problems.
To ensure your safety, do not start, stop, or change the dose of any medication without first consulting your doctor.
It is essential to inform your doctor about the following conditions before starting this medication:
Any allergies you have, including allergies to this drug, its components, or other substances, such as foods or medications. Be sure to describe the symptoms you experienced.
Kidney disease, as this may affect how your body processes the medication.
Difficulty urinating, as this could be a sign of an underlying condition that may interact with the medication.
Previous liver problems caused by this medication, as this may increase your risk of further liver damage.
Pregnancy, particularly if you are 38 weeks or more pregnant, as this medication may affect the fetus.
Special Considerations for Children:
If the patient is a child under 1 month of age, do not administer this medication, as its safety and efficacy have not been established in this age group.
Additional Important Information:
This medication may interact with other medications, including prescription and over-the-counter drugs, natural products, and vitamins. Therefore, it is crucial to provide your doctor and pharmacist with a comprehensive list of all your medications and health problems.
To ensure your safety, do not start, stop, or change the dose of any medication without first consulting your doctor.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. If you have a deficiency of the enzyme glucose-6-phosphate dehydrogenase (G6PD), you may be at risk of developing anemia. Individuals of African, South Asian, Middle Eastern, and Mediterranean descent are more likely to have low G6PD levels.
If you have diabetes and regularly test your urine for glucose, consult with your doctor to determine the most suitable testing methods for you. Do not exceed the prescribed duration of treatment, as this may increase the risk of a secondary infection.
Although rare, this medication has been associated with severe and potentially life-threatening lung problems, particularly in patients who have been taking it for 6 months or longer. These lung problems can occur without warning signs. If you are taking this medication long-term, your doctor will monitor your lung function. Immediately contact your doctor if you experience symptoms such as fever, chills, chest pain, an abnormal cough, difficulty breathing, or other respiratory problems.
If you are 65 years or older, use this medication with caution, as you may be more susceptible to side effects. Pregnant or breastfeeding women, or those planning to become pregnant, should discuss the potential benefits and risks of this medication with their doctor to ensure the best possible outcome for both mother and baby.
If you have diabetes and regularly test your urine for glucose, consult with your doctor to determine the most suitable testing methods for you. Do not exceed the prescribed duration of treatment, as this may increase the risk of a secondary infection.
Although rare, this medication has been associated with severe and potentially life-threatening lung problems, particularly in patients who have been taking it for 6 months or longer. These lung problems can occur without warning signs. If you are taking this medication long-term, your doctor will monitor your lung function. Immediately contact your doctor if you experience symptoms such as fever, chills, chest pain, an abnormal cough, difficulty breathing, or other respiratory problems.
If you are 65 years or older, use this medication with caution, as you may be more susceptible to side effects. Pregnant or breastfeeding women, or those planning to become pregnant, should discuss the potential benefits and risks of this medication with their doctor to ensure the best possible outcome for both mother and baby.
Overdose Information
Overdose Symptoms:
- Nausea
- Vomiting
- Diarrhea
- Abdominal pain
- Headache
- Dizziness
- Peripheral neuropathy (tingling, numbness)
- Hemolytic anemia (in susceptible individuals)
What to Do:
In case of overdose, seek immediate medical attention or call a poison control center (1-800-222-1222). Management is primarily supportive, including gastric lavage if ingestion was recent, and maintaining adequate hydration to promote urinary excretion.
Drug Interactions
Major Interactions
- Probenecid
- Sulfinpyrazone
Moderate Interactions
- Antacids (containing magnesium trisilicate)
- Quinolone antibiotics (e.g., ciprofloxacin, levofloxacin)
- Live bacterial vaccines (e.g., typhoid vaccine)
Monitoring
Baseline Monitoring
Renal function (CrCl)
Rationale: Nitrofurantoin is contraindicated in patients with significant renal impairment (CrCl < 60 mL/min) due to decreased efficacy and increased risk of toxicity.
Timing: Prior to initiation of therapy.
Liver function tests (ALT, AST, bilirubin)
Rationale: To establish baseline, especially if prolonged therapy is anticipated or in patients with pre-existing liver conditions, due to risk of hepatotoxicity.
Timing: Prior to initiation of therapy, particularly for long-term use.
Complete Blood Count (CBC)
Rationale: To establish baseline, as blood dyscrasias (e.g., hemolytic anemia, agranulocytosis) are rare but possible adverse effects.
Timing: Prior to initiation of therapy, especially for long-term use.
Routine Monitoring
Signs and symptoms of pulmonary toxicity (e.g., cough, dyspnea, chest pain)
Frequency: Throughout therapy, especially with long-term use.
Target: Absence of new or worsening respiratory symptoms.
Action Threshold: Discontinue drug immediately if pulmonary reactions occur.
Signs and symptoms of hepatotoxicity (e.g., fatigue, nausea, dark urine, jaundice)
Frequency: Throughout therapy, especially with long-term use.
Target: Absence of new or worsening hepatic symptoms.
Action Threshold: Discontinue drug immediately if signs of liver injury appear.
Signs and symptoms of peripheral neuropathy (e.g., paresthesias, weakness)
Frequency: Throughout therapy, especially in patients with renal impairment, anemia, diabetes, electrolyte imbalance, or vitamin B deficiency.
Target: Absence of new or worsening neurological symptoms.
Action Threshold: Discontinue drug at the first sign of neurological symptoms.
Urinalysis and urine culture
Frequency: Post-treatment, if clinically indicated, to confirm eradication of infection.
Target: Negative urine culture.
Action Threshold: Consider alternative therapy if infection persists.
Symptom Monitoring
- Resolution of urinary tract infection symptoms (e.g., dysuria, frequency, urgency)
- New or worsening cough, shortness of breath, chest pain (pulmonary toxicity)
- Unusual fatigue, nausea, vomiting, dark urine, yellowing of skin/eyes (hepatotoxicity)
- Numbness, tingling, weakness in extremities (peripheral neuropathy)
- Fever, chills, rash, joint pain (hypersensitivity reactions)
- Severe diarrhea, abdominal cramps (Clostridioides difficile-associated diarrhea)
Special Patient Groups
Pregnancy
Generally considered Category B, but contraindicated at term (38-42 weeks gestation) due to the theoretical risk of hemolytic anemia in the neonate, especially in infants with immature enzyme systems or G6PD deficiency. Use during the first trimester should be with caution and only if clearly needed.
Trimester-Specific Risks:
First Trimester:
Use with caution; limited human data, but no clear evidence of increased risk of major birth defects. Weigh potential benefits against risks.
Second Trimester:
Generally considered safe for use if indicated.
Third Trimester:
Contraindicated at term (38-42 weeks gestation) due to risk of neonatal hemolytic anemia.
Lactation
Excreted in breast milk in small amounts. Generally considered compatible with breastfeeding, but caution is advised. Contraindicated in infants with G6PD deficiency due to risk of hemolytic anemia. Monitor breastfed infants for diarrhea or signs of hemolytic anemia.
Infant Risk:
L3 (Moderate risk) - Potential for hemolytic anemia in G6PD deficient infants; monitor for gastrointestinal upset.
Pediatric Use
Contraindicated in infants less than 1 month of age due to the possibility of hemolytic anemia secondary to immature enzyme systems (e.g., glutathione instability). Use with caution in older pediatric patients, monitoring for adverse effects.
Geriatric Use
Increased risk of adverse effects, particularly pulmonary reactions, hepatotoxicity, and peripheral neuropathy, especially with long-term use. Renal function should be carefully assessed, as nitrofurantoin is contraindicated if CrCl < 60 mL/min, which is more common in the elderly. Use the lowest effective dose for the shortest duration necessary.
Clinical Information
Clinical Pearls
- Always take nitrofurantoin with food or milk to enhance absorption and minimize gastrointestinal side effects (nausea, vomiting).
- Nitrofurantoin is primarily effective for lower urinary tract infections (cystitis) and is not recommended for pyelonephritis or systemic infections due to poor tissue penetration.
- Counsel patients on the importance of completing the full course of therapy, even if symptoms improve, to prevent recurrence and resistance.
- Warn patients about potential serious side effects, including pulmonary toxicity (cough, dyspnea), hepatotoxicity (jaundice, dark urine), and peripheral neuropathy (tingling, numbness), and advise them to seek immediate medical attention if these occur.
- The urine may turn a harmless brown or rust color during treatment with nitrofurantoin.
Alternative Therapies
- Trimethoprim/sulfamethoxazole (Bactrim)
- Fosfomycin
- Pivmecillinam (not available in US)
- Fluoroquinolones (e.g., ciprofloxacin, levofloxacin) - generally reserved for more complicated UTIs or when other agents are not suitable due to resistance concerns.
- Beta-lactam antibiotics (e.g., amoxicillin/clavulanate, cephalexin)
Cost & Coverage
Average Cost:
$20 - $50 per 30 capsules (50mg)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or 2 (Generic)
General Drug Facts
If your symptoms or health issues persist or worsen, it is essential to contact your doctor promptly. To ensure safe and effective treatment, never share your medication with others or take someone else's medication. Some medications may come with a separate patient information leaflet, so it's a good idea to check with your pharmacist for more information. If you have any questions or concerns about your medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek emergency medical attention. When seeking help, be prepared to provide details about the medication taken, the amount, and the time it happened.