Nitrofurantoin Mono/mac 100mg Caps
It is used to treat or prevent a urinary tract infection (UTI).
Drug Class
Urinary anti-infective
Pharmacologic Class
Nitrofuran antibiotic
Pregnancy Category
Not available
FDA Approved
Mar 1953
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 it 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, avoid taking 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 dose, skip the missed dose and resume your regular 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, avoid taking 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 dose, skip the missed dose and resume your regular 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.
- Complete the full course of medication, even if symptoms improve, to prevent recurrence and resistance.
- Avoid antacids containing magnesium trisilicate while taking this medication.
Available Forms & Alternatives
Available Strengths:
- Nitrofurantoin Mono/mac 100mg Caps
- Nitrofurantoin Mono/mac 100mg Caps
- Nitrofurant Mac 25mg Capsules
- Nitrofurantoin Macro 100mg Capsules
- Nitrofurantoin Macro 100mg Capsules
- Nitrofurantoin Macro 50mg Capsules
- Nitrofurantoin 50mg/5ml Susp 60ml
- Nitrofurantoin 25mg/5ml Oral Susp
- Nitrofurantoin 25mg/5ml Oral Susp
Dosing & Administration
Adult Dosing
Standard Dose:
100 mg orally every 12 hours for 7 days (for uncomplicated UTI)
Dose Range:
50 - 100 mg
Condition-Specific Dosing:
uncomplicated_UTI:
100 mg orally every 12 hours for 7 days
prophylaxis:
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:
Not established for infants 1 month to 3 months.
Child:
5-7 mg/kg/day orally in 4 divided doses (for treatment, not to exceed adult dose); 1-2 mg/kg/day orally once daily or in 2 divided doses (for prophylaxis).
Adolescent:
Same as adult dosing for uncomplicated UTI.
Dose Adjustments
Renal Impairment:
Mild:
No dosage adjustment needed (CrCl > 60 mL/min).
Moderate:
Contraindicated if CrCl < 60 mL/min due to lack of efficacy and increased risk of toxicity (e.g., peripheral neuropathy, pulmonary toxicity).
Severe:
Contraindicated (CrCl < 60 mL/min).
Dialysis:
Contraindicated. Not effectively removed by dialysis.
Hepatic Impairment:
Mild:
No specific dosage adjustment provided; use with caution.
Moderate:
No specific dosage adjustment provided; use with caution due to potential for hepatotoxicity.
Severe:
No specific dosage adjustment provided; use with caution or avoid due to potential for severe hepatotoxicity.
Pharmacology
Mechanism of Action
Nitrofurantoin is reduced by bacterial flavoproteins to reactive intermediates that inactivate or alter bacterial ribosomal proteins and other macromolecules (e.g., DNA, RNA, cell wall synthesis). This leads to inhibition of vital biochemical processes of the bacteria, resulting in bacteriostatic or bactericidal activity depending on the concentration. Its broad mechanism of action minimizes the development of bacterial resistance.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 40-50% (macrocrystalline form); enhanced with food.
Tmax:
Approximately 4 hours (macrocrystalline/monohydrate).
FoodEffect:
Food significantly increases the bioavailability and prolongs the duration of therapeutic concentrations in the urine. It also helps reduce gastrointestinal upset.
Distribution:
Vd:
Not widely distributed into body tissues; primarily concentrated in the urine.
ProteinBinding:
Approximately 60%.
CnssPenetration:
Limited
Elimination:
HalfLife:
Approximately 0.3-1 hour (plasma half-life); however, urinary excretion is prolonged.
Clearance:
Rapid renal clearance.
ExcretionRoute:
Primarily renal (glomerular filtration and tubular secretion).
Unchanged:
Approximately 40-50% of the dose is excreted unchanged in the urine.
Pharmacodynamics
OnsetOfAction:
Rapid (within hours for urinary concentrations).
PeakEffect:
Not directly applicable as it's an antibiotic; peak urinary concentrations reached within 4 hours.
DurationOfAction:
Therapeutic urinary concentrations maintained for up to 12 hours with appropriate dosing.
Safety & Warnings
Side Effects
Serious Side Effects: Seek Medical Help Immediately
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you experience any of the following symptoms, contact your doctor or seek medical attention right away:
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
Note: In rare cases, 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, bloody, or watery (see below for more information on diarrhea)
Liver problems, such as:
+ Dark urine
+ Tiredness
+ Decreased appetite
+ Upset stomach or stomach pain
+ Light-colored stools
+ Vomiting
+ Yellow skin or eyes
Note: In rare cases, liver problems can be fatal.
Nerve problems, such as:
+ Burning sensation
+ Numbness
+ Tingling
Note: The risk of nerve problems may be higher in people with kidney problems, anemia, diabetes, electrolyte problems, or low vitamin B levels.
Diarrhea: Important Information
Diarrhea is a common side effect of antibiotics. However, in rare cases, a severe form of diarrhea called C. diff-associated diarrhea (CDAD) can occur. CDAD can happen during or several months after taking antibiotics. If you experience any of the following symptoms, contact your doctor right away:
Stomach pain
Cramps
Very loose, watery, or bloody stools
Do not treat diarrhea without consulting your doctor first.
Other Side Effects
Most people do not experience serious side effects, and many side effects are mild and temporary. However, if you experience any of the following side effects, contact your doctor or seek medical attention if they bother you or do not go away:
Headache
Upset stomach or vomiting
Decreased appetite
Stomach pain or diarrhea
Dizziness
Drowsiness
Tiredness
Weakness
Hair loss (this usually resolves when the medication is stopped)
Urine color change to brown (this is normal and harmless)
Reporting Side Effects
If you have questions or concerns about side effects, 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 experience any of the following symptoms, contact your doctor or seek medical attention right away:
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
Note: In rare cases, 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, bloody, or watery (see below for more information on diarrhea)
Liver problems, such as:
+ Dark urine
+ Tiredness
+ Decreased appetite
+ Upset stomach or stomach pain
+ Light-colored stools
+ Vomiting
+ Yellow skin or eyes
Note: In rare cases, liver problems can be fatal.
Nerve problems, such as:
+ Burning sensation
+ Numbness
+ Tingling
Note: The risk of nerve problems may be higher in people with kidney problems, anemia, diabetes, electrolyte problems, or low vitamin B levels.
Diarrhea: Important Information
Diarrhea is a common side effect of antibiotics. However, in rare cases, a severe form of diarrhea called C. diff-associated diarrhea (CDAD) can occur. CDAD can happen during or several months after taking antibiotics. If you experience any of the following symptoms, contact your doctor right away:
Stomach pain
Cramps
Very loose, watery, or bloody stools
Do not treat diarrhea without consulting your doctor first.
Other Side Effects
Most people do not experience serious side effects, and many side effects are mild and temporary. However, if you experience any of the following side effects, contact your doctor or seek medical attention if they bother you or do not go away:
Headache
Upset stomach or vomiting
Decreased appetite
Stomach pain or diarrhea
Dizziness
Drowsiness
Tiredness
Weakness
Hair loss (this usually resolves when the medication is stopped)
Urine color change to brown (this is normal and harmless)
Reporting Side Effects
If you have questions or concerns about side effects, 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:
- Severe or persistent nausea, vomiting, or diarrhea
- New or worsening cough, shortness of breath, or chest pain (signs of lung problems)
- Yellowing of skin or eyes, dark urine, pale stools, severe fatigue (signs of liver problems)
- Numbness, tingling, or weakness in hands or feet (signs of nerve damage)
- Severe headache, vision changes
- Fever, chills, body aches (flu-like symptoms)
- Unusual bruising or bleeding
- Severe rash or itching
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 it is not suitable for infants at this age.
Additional Important Information:
This list is not exhaustive, and it is crucial to inform your doctor and pharmacist about all your medications, including prescription and over-the-counter drugs, natural products, and vitamins. This will help ensure that it is safe to take this medication with your other medications and health conditions. Never start, stop, or change the dose of any medication without consulting your doctor first.
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 it is not suitable for infants at this age.
Additional Important Information:
This list is not exhaustive, and it is crucial to inform your doctor and pharmacist about all your medications, including prescription and over-the-counter drugs, natural products, and vitamins. This will help ensure that it is safe to take this medication with your other medications and health conditions. Never start, stop, or change the dose of any medication without consulting your doctor first.
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 a higher 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 your doctor to determine the most suitable testing methods for you.
Do not take this medication for a longer duration than prescribed. Prolonged use may increase the risk of a second infection.
Although rare, this medication has been associated with severe and potentially life-threatening lung problems, particularly in individuals 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, 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.
If you are pregnant, planning to become pregnant, or breastfeeding, discuss the potential benefits and risks of this medication with your doctor to ensure the best outcome for you and your baby.
If you have a deficiency of the enzyme glucose-6-phosphate dehydrogenase (G6PD), you may be at a higher 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 your doctor to determine the most suitable testing methods for you.
Do not take this medication for a longer duration than prescribed. Prolonged use may increase the risk of a second infection.
Although rare, this medication has been associated with severe and potentially life-threatening lung problems, particularly in individuals 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, 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.
If you are pregnant, planning to become pregnant, or breastfeeding, discuss the potential benefits and risks of this medication with your doctor to ensure the best outcome for you and your baby.
Overdose Information
Overdose Symptoms:
- Nausea
- Vomiting
- Diarrhea
- Abdominal pain
- Headache
- Dizziness
- Peripheral neuropathy (tingling, numbness)
- Hemolytic anemia (pale skin, fatigue, shortness of breath)
What to Do:
Seek immediate medical attention or call a poison control center (1-800-222-1222). Treatment is supportive; forced diuresis may be beneficial.
Drug Interactions
Contraindicated Interactions
- Probenecid (decreases renal excretion of nitrofurantoin, increasing systemic levels and toxicity, while decreasing urinary levels and efficacy)
- Sulfinpyrazone (similar to probenecid)
Major Interactions
- Live bacterial vaccines (e.g., typhoid vaccine - may reduce efficacy of vaccine)
- Antacids containing magnesium trisilicate (may reduce absorption of nitrofurantoin)
Moderate Interactions
- Quinolone antibiotics (e.g., ciprofloxacin, levofloxacin - potential antagonism, though clinical significance is debated)
- Oral contraceptives (theoretical reduction in efficacy due to altered gut flora, but not clinically proven)
Monitoring
Baseline Monitoring
Renal function (CrCl)
Rationale: To ensure adequate renal function for drug excretion and to avoid toxicity (contraindicated if CrCl < 60 mL/min).
Timing: Prior to initiation of therapy.
Liver function tests (ALT, AST, bilirubin)
Rationale: To establish baseline and monitor for potential hepatotoxicity.
Timing: Prior to initiation, especially for long-term therapy or in patients with pre-existing liver disease.
Complete Blood Count (CBC)
Rationale: To monitor for hemolytic anemia (especially in G6PD deficient patients) or other blood dyscrasias.
Timing: Prior to initiation, especially for long-term therapy.
Routine Monitoring
Renal function (CrCl)
Frequency: Periodically, especially during prolonged therapy or in elderly patients.
Target: > 60 mL/min
Action Threshold: Discontinue if CrCl falls below 60 mL/min.
Liver function tests (ALT, AST, bilirubin)
Frequency: Periodically, especially during prolonged therapy or if symptoms of liver injury develop.
Target: Within normal limits
Action Threshold: Elevations warrant investigation and potential discontinuation.
Pulmonary function tests
Frequency: If pulmonary symptoms develop (e.g., cough, dyspnea).
Target: Not applicable
Action Threshold: Abnormalities warrant immediate discontinuation.
Symptom Monitoring
- Nausea
- Vomiting
- Diarrhea
- Abdominal pain
- Dark urine (harmless, due to drug color)
- Cough
- Dyspnea (shortness of breath)
- Chest pain
- Fever
- Chills
- Jaundice (yellowing of skin/eyes)
- Unusual fatigue
- Peripheral neuropathy symptoms (tingling, numbness, weakness in hands/feet)
- Rash
- Itching
Special Patient Groups
Pregnancy
Generally considered acceptable for use during the first and second trimesters for treatment of UTIs. Contraindicated at term (38-42 weeks gestation), during labor and delivery, or when onset of labor is imminent, due to the theoretical risk of hemolytic anemia in the neonate.
Trimester-Specific Risks:
First Trimester:
Low risk; generally considered safe for uncomplicated UTIs.
Second Trimester:
Low risk; generally considered safe for uncomplicated UTIs.
Third Trimester:
Contraindicated at term (38-42 weeks gestation), during labor and delivery, or when onset of labor is imminent due to risk of neonatal hemolytic anemia, especially in G6PD deficient infants.
Lactation
Considered compatible with breastfeeding (L2). Small amounts are excreted into breast milk. Monitor infant for signs of gastrointestinal upset (e.g., diarrhea) or hemolytic anemia (especially in G6PD deficient infants). Avoid use in infants less than 1 month of age.
Infant Risk:
Low risk for most infants; higher risk for G6PD deficient infants or those less than 1 month old.
Pediatric Use
Contraindicated in infants less than 1 month of age due to the risk of hemolytic anemia. Use with caution in children, monitoring for adverse effects. Dosing is weight-based.
Geriatric Use
Use with caution due to increased risk of pulmonary toxicity, hepatotoxicity, and peripheral neuropathy, especially with long-term use. Renal function should be carefully monitored, and the drug is contraindicated if CrCl < 60 mL/min, which is common in the elderly.
Clinical Information
Clinical Pearls
- Nitrofurantoin is a first-line agent for uncomplicated lower urinary tract infections (cystitis) due to its excellent urinary concentration and low systemic exposure, which helps minimize resistance development.
- It is NOT effective for pyelonephritis or systemic infections due to poor tissue penetration.
- Always check renal function (CrCl) before prescribing; it's contraindicated if CrCl < 60 mL/min.
- Advise patients that urine may turn dark yellow or brown, which is a harmless side effect.
- Counsel patients on the importance of taking the medication with food to enhance absorption and reduce GI side effects.
- Be vigilant for signs of pulmonary toxicity (acute, subacute, or chronic), hepatotoxicity, and peripheral neuropathy, especially with prolonged use. These can be severe and irreversible.
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 options are not suitable due to resistance concerns)
Cost & Coverage
Average Cost:
Varies widely, typically $10-$50 per 30 capsules (100mg)
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 for further guidance. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so it's a good idea to check with your pharmacist. If you have any questions or concerns about this medication, don't hesitate to discuss them with 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 detailed information about the overdose, including the substance taken, the amount, and the time it occurred.