Macrodantin vs. Macrobid: Similarities and Differences
Medically reviewed by Lindsay Cook, PharmD
Macrodantin (nitrofurantoin macrocrystals) and Macrobid (nitrofurantoin monohydrate/macrocrystals) are two of the more commonly prescribed antibiotics to treat a urinary tract infection (UTI).
Both medications are orally administered (taken by mouth) capsules approved by the Food and Drug Administration (FDA) to treat UTIs caused by certain bacteria, including Escherichia coli (E. coli).
The active ingredient in Macrodantin is nitrofurantoin macrocrystals. Macrocrystals are larger crystals of the drug nitrofurantoin. Nitrofurantoin macrocrystals are absorbed slower into your body than regular nitrofurantoin.
Macrobid 100 milligram (mg) capsules contain 25 mg of nitrofurantoin macrocrystals and 75 mg of nitrofurantoin monohydrate.
Combining these two forms of nitrofurantoin helps Macrobid stay in your body longer than Macrodantin. Because of this, Macrobid capsules may be taken twice daily, while Macrodantin is typically taken four times daily.
Keep reading to learn more about the differences and similarities between Macrodantin and Macrobid.
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Understanding Antimicrobial Agents
Antimicrobial agents are substances used to prevent or treat infections.
They can include antiseptics, antibiotics, antifungals, and antivirals, among others.
Antimicrobials can kill microbes (germs) that cause illnesses or prevent them from growing and multiplying.
What They Treat
Antibiotics are a type of antimicrobial. Antibiotics only treat conditions caused by bacteria.
Examples include:
Macrodantin and Macrobid as Antibiotics
Macrodantin and Macrobid fall into the group of antimicrobials called antibiotics.
The first antibiotic used was penicillin. It was discovered in 1928 by Scottish scientist Alexander Fleming.
Penicillin is made from a mold called Penicillium. Another commonly used antibiotic made from this mold is Amoxil (amoxicillin).
Although Macrodantin and Macrobid are antibiotics, they differ from penicillin and amoxicillin.
Nitrofurantoin, the active ingredient in Macrodantin and Macrobid, is not made from a mold.
Instead, it's made by combining specific chemical molecules in a lab.
Treating UTIs
A UTI is an infection that occurs in any part of the urinary system.
These can include the kidneys, ureters (tubes that connect the kidneys to the bladder), bladder, or urethra (a tube connected to your bladder through which urine passes out of the body).
UTIs occur when certain bacteria enter the urinary system. Some ways this can happen include having sexual activity, using spermicide or a diaphragm as a birth control method, or using a urinary catheter.
The most common bacteria that may cause a UTI is E. coli. Most UTIs are not severe and can be easily treated with a few days of antibiotic treatment.
Notable Statistics
UTIs are not uncommon.
About 50% to 70% of people assigned female at birth will report having at least one UTI sometime during their lifetime.
UTIs occur more frequently in females than males at birth.
What Is Macrodantin?
Macrodantin is an orally administered antibiotic approved by the FDA to treat UTIs caused by certain bacteria, including E. coli.
This antibiotic does not work for UTIs that affect the kidneys and should not be used for this purpose.
Macrodantin is an oral capsule approved for adults and children 1 month and older.
The active ingredient in Macrodantin, nitrofurantoin, is also available in liquid form for children and adults who may have difficulty swallowing capsules.
The liquid form of nitrofurantoin is available under the brand name Furadantin.
Macrodantin and Furadantin are also available under the generic name nitrofurantoin.
Off-Label Uses
In some cases, healthcare providers may prescribe Macrodantin for uses or at dosages that differ from the drug's initially approved use.
This is called an off-label use.
Macrodantin is sometimes used off-label to help prevent UTIs.
How It Works
When you take a dose of Macrodantin, most of the drug is not absorbed into your bloodstream as with other antibiotics.
Instead, the medication dissolves in the urine in your bladder, where it prevents bacteria from making proteins and other parts essential to their structure.
In doing so, Macrodantin kills the bacteria and treats your infection.
What Is Macrobid?
Macrobid is an orally administered antibiotic similar to Macrodantin. The FDA also approved it to treat UTIs caused by certain bacteria, including E. coli.
Like Macrodantin, Macrobid should not be used to treat infections that affect the kidneys.
This drug is an oral capsule approved for use in adults and children 12 years and older.
It's also available in a generic form called nitrofurantoin (monohydrate/macrocrystals).
How It Works
Macrobid works similarly to Macrodantin, with one difference. Macrobid is made up of nitrofurantoin monohydrate and nitrofurantoin macrocrystals.
When nitrofurantoin monohydrate mixes with fluids in your stomach and intestines, it forms a gel that slowly releases the drug.
Because of this, the effects of Macrobid last longer, and the medication may be taken less frequently throughout the day than Macrodantin.
Dosing Guidelines
The table below describes dosing recommendations for adults taking Macrodantin, Macrobid, or Furadantin.
Remember that these are dosages recommended by the manufacturers of these drugs.
If your healthcare provider prescribes any of these drugs, take the medication exactly as prescribed.
| Macrodantin capsules: | Macrobid capsules: | Furadantin suspension (liquid): |
Dosing for UTI treatment: | • 50–100 mg four times per day | • 100 mg every 12 hours (two times per day) | • 50–100 mg four times per day |
Dosing for UTI prevention: | • 50–100 mg at bedtime | • N/A | • 50–100 mg at bedtime |
Dosing for Children
The following provides basic dosing guidelines for using Macrobid vs. Macrodantin in children.
Macrobid
The recommended Macrobid dosage for children ages 12 years and older is the same as for adults.
Macrodantin
Macrodantin is approved for use in children ages 1 month and older. In this case, Macrodantin is dosed in milligrams based on your child's kilograms (kg) body weight, with 1 kg equaling about 2 pounds.
Your child's healthcare provider will calculate their Macrodantin dosage based on weight.
They may prescribe Furadantin suspension instead of Macrodantin capsules if your child cannot swallow capsules or their dosage is not available in capsule form.
The recommended Macrodantin dosage for treating UTIs in children is 5 to 7/kg per 24 hours. The total daily dose is divided into four doses given throughout the day.
To help prevent UTIs in children, the dosage is 1 mg/kg per 24 hours. This dosage may be given in a single dose or two divided doses.
Which Drug Works More Quickly?
Both Macrodantin and Macrobid dissolve in your urine and start working as soon as the first day you take your dose.
The effects of Macrodantin last about six hours.
With Macrobid, the drug is released in your body slowly over time. Its effects last about 12 hours. About 25% of Macrobid is released from your body in your urine.
Side Effects and Precautions
As with all drugs, it's possible to experience side effects from Macrodantin or Macrobid.
Macrodantin and Macrobid's most common side effects are mild and don't require medical attention. However, in rare cases, side effects may be more serious.
It's important to let a healthcare provider know if you have bothersome side effects while taking Macrodantin or Macrobid.
Common Side Effects of Macrodantin
Common side effects of Macrodantin include:
Brown-colored urine
Common Side Effects of Macrobid
Common side effects of Macrobid include:
Nausea
Headache
Brown-colored urine
Severe Side Effects of Macrodantin and Macrobid
Although rare, Macrodantin and Macrobid may cause severe side effects in some people.
Examples include:
Lung problems, such as pulmonary fibrosis (causes scarring of the lungs)
Liver damage, including hepatitis (inflammation of the liver)
Peripheral neuropathy (damage to nerves outside the brain and spinal cord)
Hemolytic anemia (low red blood count due to the destruction of red blood cells)
Long-term Side Effects of Macrodantin and Macrobid
Many side effects of Macrodantin and Macrobid go away on their own within a few days or when you stop taking the medication.
However, some rare side effects may last longer.
Examples of potential long-term side effects of Macrodantin and Macrobid include:
Lung problems, such as pulmonary fibrosis: The risk for these side effects is higher if you take Macrodantin or Macrobid for six months or longer. Your healthcare provider will monitor you for signs of lung problems if you take these medications long-term.
Liver damage, including hepatitis: Be sure to tell your healthcare provider if you have liver problems. They may recommend a different antibiotic to treat your UTI.
Peripheral neuropathy: Talking with your healthcare provider about your health history before starting treatment with Macrodantin or Macrobid is important. Certain conditions, including diabetes and kidney problems, can increase your risk of having peripheral neuropathy.
Guidance for Safe Use
Your healthcare provider will prescribe your dosage of Macrodantin or Macrobid based on several factors, including your condition's severity and age. Be sure to follow their instructions carefully.
If you miss a dose of Macrodantin or Macrobid, take it as soon as you remember.
Then, take the next dose after your regularly scheduled number of hours have passed. Do not take two doses together to make up for a missed dose.
The manufacturers of Macrodantin and Macrobid recommend taking your dose with food to increase the amount of the drug that your body absorbs.
Macrodantin
If you're taking Macrodantin for UTI treatment, your healthcare provider will likely have you take the medication four times per day.
This means the dose should be spaced out every six hours.
Most people take Macrodantin for seven days or at least three days after no bacteria is found in their urine.
Macrobid
Macrobid doses are typically taken twice daily, spaced out every 12 hours.
This treatment typically lasts for seven days.
Taking Macrodantin Long-Term
Sometimes, healthcare providers may prescribe Macrodantin long-term to help prevent UTIs. Typically, this dose is taken once per day at bedtime.
Keep in mind that taking Macrodantin for longer than six months can increase your risk of having lung-related severe side effects, such as pulmonary fibrosis.
If you take Macrodantin long term, your healthcare provider will monitor you for signs of lung problems.
Be sure to let them know right away if you have any of the following symptoms while taking Macrodantin:
Pregnancy and Breastfeeding
It's not known whether it's safe to take Macrodantin or Macrobid during pregnancy.
If you're pregnant or planning a pregnancy, let your healthcare provider know before you start taking either of these medications.
They'll help you decide whether they're safe during your pregnancy.
Nitrofurantoin, the active ingredient in Macrodantin and Macrobid, passes into breast milk and may cause harm to children younger than 1 month.
Due to this risk, you should not breastfeed a child younger than 1 month while taking Macrodantin or Macrobid.
Potential for Interaction
Macrodantin and Macrobid may interact with some medications.
Avoid taking antacids that contain the ingredient magnesium trisilicate with Macrodantin or Macrobid. This ingredient may decrease your body's absorption of Macrodantin and Macrobid.
Examples of antacids that contain magnesium trisilicate are:
Gaviscon Regular Strength Chewable Tablets (aluminum hydroxide/magnesium trisilicate)
Gaviscon Extra Strength Chewable Tablets (aluminum hydroxide/magnesium trisilicate)
On the other hand, the gout medication Probalan (probenecid) may cause nitrofurantoin to build up in your body. This may increase your risk of side effects from Macrodantin and Macrobid.
Review of Efficacy
If your healthcare provider prescribes Macrodantin or Macrobid, you may be interested in knowing whether these medications are safe and effective for a UTI.
In medical guidelines for treating UTIs, nitrofurantoin is recommended as a first choice for treating UTIs affecting the bladder and urethra.
Additionally, a study found that bacteria that cause UTIs were less likely to become resistant to nitrofurantoin than other antibiotics used to treat UTIs.
Alternate Treatment Options
If you have a UTI, you'll likely need an antibiotic to treat the infection.
The following measures may help you get better while taking an antibiotic:
Take your antibiotic exactly as your healthcare provider prescribes it.
Ensure you finish taking all the antibiotics prescribed, even if you feel better. Stopping your antibiotic treatment too soon may cause the infection to return.
Drink plenty of water or other fluids.
Urinate when you feel the urge.
The following measures may help to prevent a UTI:
Drink plenty of fluids, especially water, daily.
Urinate after sex.
Don't hold your urine; urinate when you feel the urge.
Opt for showers instead of baths.
Avoid using douches, sprays, or powders in your genital area.
People with a vagina should wipe from front to back after urinating or having a bowel movement.
Summary
Antimicrobial agents are substances that prevent or treat infections. Antibiotics like Macrodantin and Macrobid are a type of antimicrobial agents.
Antibiotics typically work by killing bacteria or preventing them from growing.
Macrodantin and Macrobid are both FDA-approved to treat UTIs. Both drugs have the same active ingredient: nitrofurantoin. However, the form of nitrofurantoin in Macrobid allows the drug to be released slowly over time into your body.
Because of this, Macrobid is only taken two times per day. Macrodantin is typically taken four times per day.
As with any antibiotic, it's important to take Macrodantin or Macrobid exactly as prescribed. Do not stop taking the drug until you've taken all the doses prescribed.
Stopping your antibiotic treatment too soon may cause the infection to return. If it comes back, it may be more difficult to treat.
Frequently Asked Questions
How do I store Macrodantin vs. Macrobid?
Store Macrodantin capsules at room temperature (68–77 degrees F).
Macrobid Capsules may be stored at temperatures between 59–86 degrees F.
Like all medications, Macrodantin and Macrobid should be kept out of the sight and reach of children and pets.
Can people of African descent safely take Macrodantin or Macrobid?
The manufacturers of Macrodantin and Macrobid do not specify whether these medications are safe to take based on your race.
It's important to note that these drugs may not be safe to take if you have certain health conditions, including kidney or liver disease.
Let your provider known your health history, which can help determine whether Macrodantin or Macrobid is safe for you to take.
Read the original article on Verywell Health.
