Nitrofurantoin Macro 100mg Capsules
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
Aug 1991
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 with absorption 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. If you have unused or expired medication, 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. You can also check with your pharmacist about 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, 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. If you have unused or expired medication, 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. You can also check with your pharmacist about 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 minimize stomach upset (nausea, vomiting).
- Drink plenty of fluids unless otherwise advised by your doctor.
- Complete the full course of medication, even if symptoms improve, to prevent the infection from returning and to reduce the risk of antibiotic resistance.
- This medication may cause your urine to turn a rust-yellow to brownish color. This is a harmless side effect.
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 every 12 hours for 7 days
Dose Range:
100 - 100 mg
Condition-Specific Dosing:
acuteUncomplicatedUTI:
100 mg every 12 hours for 7 days
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 12 years for macrocrystals. For acute uncomplicated UTI in children >12 years: 100 mg every 12 hours for 7 days.
Child:
Not established for children <12 years for macrocrystals. For acute uncomplicated UTI in children >12 years: 100 mg every 12 hours for 7 days.
Adolescent:
100 mg every 12 hours for 7 days (for acute uncomplicated UTI)
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment needed, but monitor renal function.
Moderate:
Contraindicated if CrCl < 60 mL/min due to increased risk of toxicity and decreased efficacy.
Severe:
Contraindicated (CrCl < 60 mL/min).
Dialysis:
Contraindicated. Not effectively removed by dialysis.
Hepatic Impairment:
Mild:
No specific adjustment, use with caution.
Moderate:
No specific adjustment, use with caution and monitor liver function.
Severe:
No specific adjustment, use with caution and monitor liver function. Contraindicated in patients with a history of cholestatic jaundice/hepatic dysfunction associated with prior nitrofurantoin use.
Pharmacology
Mechanism of Action
Nitrofurantoin is reduced by bacterial flavoproteins to reactive intermediates that inactivate or damage bacterial ribosomal proteins, DNA, RNA, and other macromolecules. This leads to inhibition of bacterial protein synthesis, aerobic energy metabolism, DNA synthesis, RNA synthesis, and cell wall synthesis. The broad spectrum of activity is due to the multiple targets of these reactive intermediates.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 40-50% (macrocrystals, enhanced by food)
Tmax:
Approximately 4 hours
FoodEffect:
Food significantly increases the absorption and bioavailability of nitrofurantoin macrocrystals, and prolongs the duration of therapeutic concentrations in the urine.
Distribution:
Vd:
Approximately 0.8 L/kg
ProteinBinding:
Approximately 60%
CnssPenetration:
Limited
Elimination:
HalfLife:
Approximately 0.3 to 1 hour
Clearance:
Not available
ExcretionRoute:
Primarily renal (glomerular filtration and tubular secretion)
Unchanged:
Approximately 20-40% of the dose is excreted unchanged in the urine.
Pharmacodynamics
OnsetOfAction:
Within hours (urinary concentrations)
PeakEffect:
Approximately 4 hours (urinary concentrations)
DurationOfAction:
Up to 12 hours (urinary concentrations)
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, bloody, or watery (may be a sign of C. diff-associated diarrhea, a potentially life-threatening condition)
Liver problems, such as:
+ Dark urine
+ Tiredness
+ Decreased appetite
+ Upset stomach or stomach pain
+ Light-colored stools
+ Vomiting
+ Yellow skin or eyes (jaundice)
Nerve problems, such as:
+ Burning sensation
+ Numbness
+ Tingling
+ Abnormal sensations (especially if you have kidney problems, anemia, diabetes, electrolyte problems, or low vitamin B levels)
Other Possible Side Effects
Most people do not experience severe side effects, and some may not have any side effects at all. However, if you notice any of the following symptoms, 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
Fatigue
Weakness
Hair loss (usually reversible when the medication is stopped)
Urine color change to brown (harmless and temporary)
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 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, bloody, or watery (may be a sign of C. diff-associated diarrhea, a potentially life-threatening condition)
Liver problems, such as:
+ Dark urine
+ Tiredness
+ Decreased appetite
+ Upset stomach or stomach pain
+ Light-colored stools
+ Vomiting
+ Yellow skin or eyes (jaundice)
Nerve problems, such as:
+ Burning sensation
+ Numbness
+ Tingling
+ Abnormal sensations (especially if you have kidney problems, anemia, diabetes, electrolyte problems, or low vitamin B levels)
Other Possible Side Effects
Most people do not experience severe side effects, and some may not have any side effects at all. However, if you notice any of the following symptoms, 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
Fatigue
Weakness
Hair loss (usually reversible when the medication is stopped)
Urine color change to brown (harmless and temporary)
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:
- New or worsening cough, shortness of breath, or chest pain (signs of lung problems)
- Yellowing of skin or eyes (jaundice), dark urine, unusual tiredness, nausea, vomiting, or stomach pain (signs of liver problems)
- Tingling, numbness, or weakness in your hands or feet (signs of nerve damage)
- Severe diarrhea (possibly with blood or mucus)
- Unexplained fever or chills
- Skin rash, itching, or hives
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 to ensure safe treatment:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Describe the allergic reaction you experienced, including the symptoms that occurred.
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 the 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 approved for use in this age group.
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 identify potential interactions and ensure safe treatment. 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 to ensure safe treatment:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Describe the allergic reaction you experienced, including the symptoms that occurred.
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 the 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 approved for use in this age group.
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 identify potential interactions and ensure safe treatment. 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 should exercise caution, as this condition may increase your 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 exceed the prescribed duration of treatment with this medication, as this may lead to the development of a secondary infection.
Although rare, this medication has been associated with severe and potentially life-threatening lung problems, particularly in individuals who have been taking it for six 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 of age 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 possible outcome for you and your baby.
If you have a deficiency of the enzyme glucose-6-phosphate dehydrogenase (G6PD), you should exercise caution, as this condition may increase your 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 exceed the prescribed duration of treatment with this medication, as this may lead to the development of a secondary infection.
Although rare, this medication has been associated with severe and potentially life-threatening lung problems, particularly in individuals who have been taking it for six 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 of age 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 possible outcome for you and your baby.
Overdose Information
Overdose Symptoms:
- Nausea
- Vomiting
- Diarrhea
What to Do:
In case of overdose, seek immediate medical attention or call a poison control center (e.g., 1-800-222-1222). Management is primarily supportive; forced diuresis may be helpful.
Drug Interactions
Contraindicated Interactions
- Magnesium trisilicate-containing antacids (decreased absorption of nitrofurantoin)
- Probenecid (decreased renal excretion of nitrofurantoin, increased toxicity, decreased efficacy)
- Sulfinpyrazone (decreased renal excretion of nitrofurantoin, increased toxicity, decreased efficacy)
Major Interactions
- Live bacterial vaccines (e.g., Typhoid vaccine, oral: Nitrofurantoin may reduce the therapeutic effect of the vaccine)
Moderate Interactions
- Quinolone antibiotics (e.g., Nalidixic acid, Ciprofloxacin: Possible antagonism, though clinical significance is debated)
Monitoring
Baseline Monitoring
Renal function (CrCl)
Rationale: To assess appropriate dosing and contraindications, especially in elderly patients or those with known renal impairment.
Timing: Prior to initiation of therapy.
Liver function tests (LFTs)
Rationale: To establish baseline, especially if long-term therapy is considered or in patients with pre-existing liver conditions.
Timing: Prior to initiation of therapy (if indicated).
Complete Blood Count (CBC)
Rationale: To establish baseline, especially if long-term therapy is considered, due to rare reports of hematologic reactions.
Timing: Prior to initiation of therapy (if indicated).
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 symptoms develop and consider appropriate diagnostic evaluation.
Signs and symptoms of hepatic toxicity (e.g., jaundice, fatigue, dark urine, abdominal pain)
Frequency: Throughout therapy, especially with long-term use.
Target: Absence of new or worsening hepatic symptoms.
Action Threshold: Discontinue drug immediately if symptoms develop and consider appropriate diagnostic evaluation.
Signs and symptoms of peripheral neuropathy (e.g., tingling, numbness, weakness)
Frequency: Throughout therapy, especially with long-term use or in patients with predisposing conditions (renal impairment, anemia, diabetes, electrolyte imbalance, vitamin B deficiency).
Target: Absence of new or worsening neurological symptoms.
Action Threshold: Discontinue drug immediately if symptoms develop.
Symptom Monitoring
- Cough
- Dyspnea
- Chest pain
- Fever
- Chills
- Jaundice
- Fatigue
- Anorexia
- Nausea
- Vomiting
- Abdominal pain
- Dark urine
- Tingling sensation (paresthesia)
- Numbness
- Weakness
- Dizziness
- Headache
- Muscle aches
- Joint pain
- Skin rash
- Itching
Special Patient Groups
Pregnancy
Generally considered low risk during the first and second trimesters, but contraindicated at term (38-42 weeks gestation) and during labor/delivery due to the risk of hemolytic anemia in the neonate, especially in infants with immature enzyme systems (e.g., G6PD deficiency). Use only if clearly needed and benefits outweigh risks.
Trimester-Specific Risks:
First Trimester:
Low risk, but use only if clearly needed.
Second Trimester:
Low risk, but use only if clearly needed.
Third Trimester:
Contraindicated at 38-42 weeks gestation and during labor/delivery due to risk of neonatal hemolytic anemia.
Lactation
Excreted in breast milk. Generally considered compatible with breastfeeding, but caution is advised in infants with G6PD deficiency or those less than 1 month of age due to the theoretical risk of hemolytic anemia.
Infant Risk:
Low to moderate risk. Monitor for signs of hemolytic anemia in susceptible infants.
Pediatric Use
Contraindicated in infants less than 1 month of age. For children >12 years, dosing is similar to adults for acute uncomplicated UTIs. Dosing for younger children is typically based on weight for other formulations, but macrocrystals are generally not recommended for children under 12 years.
Geriatric Use
Use with caution due to increased risk of pulmonary, hepatic, and neurological toxicities, particularly in patients with impaired renal function. Contraindicated if CrCl < 60 mL/min. Closely monitor renal function and for adverse effects.
Clinical Information
Clinical Pearls
- Always take nitrofurantoin with food or milk to enhance absorption and reduce gastrointestinal upset.
- Inform patients that their urine may turn a harmless rust-yellow to brownish color.
- Nitrofurantoin is effective only for lower urinary tract infections (cystitis) and is not recommended for pyelonephritis or systemic infections due to poor tissue penetration.
- Long-term use (e.g., for prophylaxis) requires careful monitoring for pulmonary fibrosis, hepatotoxicity, and peripheral neuropathy.
- Contraindicated in patients with a creatinine clearance (CrCl) less than 60 mL/min due to increased risk of toxicity and decreased efficacy.
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:
$100 - $250 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's 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 be sure to check with your pharmacist for more information. 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 details about the overdose, including the medication taken, the amount, and the time it occurred.