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Macrobid - Uses, Dosage, Side Effects, and Precautions

Published on Nov 01, 2022 and last reviewed on Nov 17, 2022   -  6 min read


Macrobid is an antibacterial drug used to prevent and treat urinary tract infections. Learn more about its uses, dosage, side effects, precautions, and more.


Macrobid is the brand name of Nitrofurantoin. The drug is available in tablets, capsules, and liquid forms. It is a broad spectrum that acts against gram-positive and gram-negative bacteria. It treats and prevents acute or recurrent lower urinary tract infections. The drug works by inhibiting protein synthesis by targeting the nascent peptide exit tunnel and selectively inhibiting the translation of a subset of cellular proteins.

It is the first line of therapy for uncomplicated lower urinary tract infections because of the emerging resistance to other antibiotics such as Co-trimoxazole, Trimethoprim, Amoxicillin, and Fluoroquinolones. Macrobid is indicated in adults, children, and infants above one month.

Drug Group:

Macrobid belongs to broad-spectrum bactericidal antibiotics and is effective against the most common urinary tract pathogens like Escherichia coli, Klebsiella, Staphylococcus aureus, and Enterococcus. Urinary tract infections can affect the urinary tract, bladder, urethra, or kidneys.

What Is Macrobid Used to Treat?

Macrobid is an antimicrobial used widely to treat lower urinary tract infections. The primary cause of UTI is the colonization of bacteria in the urethra, a tube that carries urine from the urinary bladder. Urinary tract infections are more common in women because the urethra is shorter and closer to the anus, where bacteria is usually present. The bacteria quickly ascend the urinary bladder through the urethra and cause infection. UTIs are also commonly seen in older adults who have difficulty emptying the bladder.

  • It is used for UTIs following surgical procedures and infection treatment due to E.coli, Klebsiella, and Enterobacter susceptible strains.
  • Macrobid is also used to treat cystitis, a more bladder-specific infection. The bacteria travel up to the bladder and cause inflammation and infection.
  • Macrobid can also be used to prevent UTIs in children where the infections keep coming back.

How Does Macrobid Work?

Macrobid is bactericidal, and its mechanism of action is different from other antibacterials. The bacterial flavoproteins reduce Macrobid to form reactive intermediates. The altered bacterial ribosomal proteins. It inhibits the enzymes synthesizing the cell wall, DNA, RNA, and other metabolic enzymes. Macrobid acts by maintaining a low serum concentration in the lower urinary tract and does not affect the bowel flora. Hence, it provides continued effectiveness and minimal resistance.

What Is the Onset of Action of Macrobid?

About 80 % of Macrobid reaches systemic blood circulation when orally administered. It is well absorbed in the gastrointestinal tract and distributed quickly into body fluids. Macrobid reaches its maximum therapeutic concentration in the lower urinary tract. The drug is metabolized in the liver and rapidly excreted in large amounts in bile and urine, except for the active drug secretion in the kidney. Macrobid transfer across the body membrane by diffusion. The biliary and urinary excretion of the unchanged drug and enzymatic degradation is the primary means of elimination. It takes three to five days for the drug to work and may require a week for all the symptoms to clear..


There have been no reports of habit-forming tendency in people taking Macrobid.

Expiry Date:

Avoid taking this medicine after it expires. Instead, check for the expiry date written on the back of the pack.

What is the Dosage of Macrobid?

Macrobid is available as tablets in 50 mg and 100 mg and as a modified-release capsule of 100 mg.

Dosage of Macrobid

IMPORTANT: The patient must complete the course of antibiotics. If you stop the antibiotic too soon, the bacteria will again start multiplying and may again cause infection. Also, do not start an antibiotic, increase the dosage or stop the intake of the drug abruptly without consulting with your treating physician. Do not take the drug without the advice of the doctor.

How to Use Macrobid?

Macrobid should be taken with food to avoid an upset stomach and for better absorption. Swallow the medicine as a whole with water.

  • To Treat UTI - Macrobid is taken twice a day for three to seven days. Space the doses throughout the day. For severe UTIs, it is taken four times a day.
  • To Prevent UTIs - Macrobid is taken once a day at night. If taking Macrobid as a liquid, shake the bottle well before use. Always correctly measure the correct dose and avoid taking it more or less. If you have other health conditions or are under medications, your doctor will alter the dosage accordingly.

Missed Dose:

If you are taking Macrobid and have missed a dose, you can take it as soon as you remember. However, do not take two tablets together as it may result in severe side effects.

What Are the Drug Warnings and Precautions?

  • Pregnancy and Breastfeeding - Although Macrobid can be taken during pregnancy, it is essential to tell your doctor if you are pregnant or are trying for pregnancy. Also, it should be taken only when indicated. The drug passes into breast milk and is not recommended while breastfeeding.

  • Other Medicines - Macrobid interacts with magnesium salicylate, choline magnesium salicylate, or other gout medications. Therefore, if you are taking any medications, inform your doctor beforehand to avoid serious side effects.

  • Anemia - Macrobid must be used with caution in patients with anemia.

  • Allergy - If you have allergies to other medicines, tell your doctor. Do not take Macrobid if you have an allergic reaction to it.

  • Kidney Diseases - A diseased kidney will not be able to clear the Macrobid from the body and can increase the side effects. So, it is used with caution in patients with renal problems.

  • Liver Diseases - Macrobid should not be taken if your liver is damaged.

  • Geriatric Population - In older adults, the kidneys may not function well. The delays in processing Macrobid may raise the risk of side effects. Before prescribing Macrobid for the older population, weigh the risk of side effects.

  • Lung Disorders - Patients with pulmonary conditions need close monitoring, especially the elderly.

  • Children - Macrobid should not be given to infants below one month.

  • Self-Medication - Macrobid should not be taken unless prescribed by the doctor. Always hand it in as advised by a doctor.

  • False Positive Urinary Glucose - The urine color is yellow to brown after taking Macrobid and might be misleading.

  • Driving and Handling Machines - Macrobid may cause dizziness and drowsiness. Avoid operating machinery and driving after taking Macrobid.

What Are the Side Effects of Macrobid?

Common side effects of Macrobid include

  • Headaches.

  • Rash.

  • Itching.

  • Nausea.

  • Vomiting.

  • Change in urine color.

  • Loss of appetite.

  • Diarrhea.

  • Abdominal pain.

Serious side effects of Macrobid:

  • Lung injury.

  • Anemia.

  • Exfoliative dermatitis.

  • Vasculitis.

  • Difficulty in breathing.

  • Chest pain.

  • The mild side effects usually reduce within a few days. The above are just some of the side effects of Macrobid. Consult the doctor if you have severe symptoms or serious discomfort after taking Macrobid.

What Are the Interactions of Macrobid?

Macrobid may interact with other drugs, food, and other supplements, which may decrease the effectiveness of a drug or may increase the risk of side effects.

Drug Interactions:

  • Macrobid interacts with the below drugs.

  • Probenecid.

  • Sulfinpyrazone.

  • Magnesium trisilicate antacids.

  • Live Tuberculosis vaccine.

  • Live typhoid vaccine.

  • Quinolones.

  • Magnesium salicylate.

  • Choline magnesium salicylate.

Food Interactions:

  • Grapefruit - It is best to avoid grapefruit and calcium-fortified foods with Macrobid. Macrobid should be taken with food or milk.
  • Smoking - Smoking may interfere with the antibiotic's absorption, distribution, metabolism, or excretion, and smokers may require higher doses.

  • Alcohol - Drinking alcohol while taking Macrobid can worsen the side effects such as nausea, dizziness, vomiting, and headache.

With Diseases:

  • Liver Diseases - Avoid taking Macrobid if you have liver dysfunctions. Therefore, inform your doctor if you have any liver disorders.

  • Renal Diseases - Do not take Macrobid if you have renal impairment, as it cannot be eliminated, increasing the side effects.

What Are the Common Brands of Macrobid?

  1. Tablet Furadantin 100 mg.

  2. Tablet Furantex 50 mg.

  3. Capsule Urifast.

  4. Tablet Urifur-SR 1900 mg.

  5. Tablet Nitrofem 100 mg SR.

  6. Tablet Martifur MR 100 mg.

  7. Capsule Niftran 100 mg.

  8. Tablet Uribid 100 mg.

  9. Tablet Niftas 100 mg.

  10. Nitrofurantoin Oral suspension 25 mg.

Frequently Asked Questions


What Is the Use of Macrobid?

Macrobid is an antibiotic used predominantly for the treatment of urinary tract infections (UTIs). It is also used for UTIs after surgical procedures and infection caused by E.coli, Enterobacter, and Klebsiella susceptible strains.


Can Macrobid Be Considered a Form of Amoxicillin?

Macrobid is not a form of Amoxicillin. Macrobid and Amoxicillin are two different antibiotics. Macrobid belongs to the nitrofuran antibiotic group, and Amoxicillin is a part of the penicillin family.


Is Macrobid an Antibiotic Beneficial in Urinary Tract Infection?

Yes, Macrobid is a commonly prescribed medication used to treat or prevent uncomplicated urinary tract infections (UTIs). However, it can turn urine dark yellow or brown. The medication leads to severe lung problems if it is used for a period of more than six months.


How Long Does Macrobid Take to Act in Urinary Tract Infection?

Macrobid usually shows acts and shows improvement within 24 hours of administration. The symptoms of the infections usually subside after three days. If symptoms do not improve or worsen, the doctor must be consulted immediately. The patient might start feeling better even before the antibiotic course is completed.


What Foods Must Be Avoided During Macrobid Administration?

During Macrobid administration, the patient must avoid eating high-sugar foods, large amounts of caffeine consumption, and drinking excessive amounts of alcohol. They are adviced to consume low-fiber and bland foods if symptoms of diarrhea or stomach upset are experienced after the administration of the antibiotics.


What Are the Side Effects Caused by Macrobid?

The side effects caused by Macrobid include dizziness, nausea, headache, drowsiness, weakness, indigestion, bloating, vomiting, loss of appetite, muscle or joint pain, rash, itching, and temporary hair loss.


Does Macrobid Cause Fatigue?

Administration of antibiotics may lead to tiredness or fatigue. It is an indication of the infection being treated by the antibiotics or may be considered a side effect of the antibiotic treatment. Macrobid may cause hemolysis or red blood cell damage causing tiredness, weakness, and pale skin.


Is Administration of Macrobid for Three Days Enough to Treat Urinary Tract Infection?

Yes, most Macrobid is prescribed for a short period, usually lasting between three to seven days. If multiple urine infections have occurred in a short duration, the doctor might prescribe a longer course of treatment, often extending up to six months.


Can a Yeast Infection Be Caused by Macrobid?

Prolonged or repeated usage of Macrobid may result in oral thrush or vaginal yeast infection. The doctor must be consulted immediately if such patches are noticed in the mouth or the vagina.


What Are the Effects of Drinking Caffeine With Macrobid?

Consumption of large amounts of caffeine during the administration of antibiotics like Nitrofurantoin and Macrobid must be avoided as these medications can cause irritation in the stomach.


Does Macrobid Belong to the Penicillin Family?

No, Macrobid does not belong to the penicillin family and is not related to other antibiotics of this class. Hence, Macrobid can be prescribed or administered in patients who are allergic to certain antibiotics.


Can Yogurt Be Eaten With Macrobid?

Yes, yogurt can be eaten with Macrobid. However, it must be taken at least two hours after the  Macrobid dose. Yogurt helps to prevent gastrointestinal side effects like  vomiting, nausea, lack of appetite, abdominal pain, or diarrhea.


What Are the Other Indications of Macrobid Apart From UTI Treatment?

Macrobid can also be used for treating cystitis, a bladder-specific infection where the bacteria moves up to the bladder and causes infection and inflammation. Macrobid is also used for the prevention of urinary tract infections in children in the case of recurrent infections.


What Is the Reason Behind Macrobid Turning Urine Orange?

During the administration of this medicine, the urine might turn dark or orange because the active ingredient is a reddish-brown powder. However, this does not indicate any harm and usually disappears once the medication is discontinued.


Can Macrobid Be Used as an Analgesic?

Macrobid is not an analgesic, it is an antibiotic used to treat bladder infections, and it works by stopping the growth of bacteria. It might relieve pain by treating the infection. This medicine is not usually used for treating infections outside the bladder.


Can Macrobid Cause Depression?

Recurrent exposure or use of antibiotics may be associated with an increased risk for depression and anxiety. Benign intracranial hypertension (headache syndrome characterized by raised intracranial pressure), confusion, depression, and psychotic reactions have been documented. However, cases of such side effects are rare.

Article Resources

Last reviewed at:
17 Nov 2022  -  6 min read




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