Is Nitrofurantoin a Penicillin Antibiotic?

Table of Contents

Share Post

Antibiotics are typically classified based on common chemical structures, spectra of antibacterial activity, or mechanisms of action. Antibiotic classes help to understand and categorize the full range of antibiotic medications available and how they work. Some typical antibiotic classes include aminoglycosides, carbapenems, cephalosporins, fluoroquinolones, macrolides, penicillin, and tetracyclines. Is Nitrofurantoin a penicillin antibiotic?

Nitrofurantoin is an antibiotic medication prescribed to fight specific bacteria in the urinary tract. Doctors commonly prescribe Nitrofurantoin as an effective treatment for urinary tract infections caused by particular bacteria such as Klebsiella, Enterobacter cystitis, E. coli, Enterococcus, and Staphylococcus aureus.

What is Nitrofurantoin?

Nitrofurantoin is a commonly recommended antibiotic for infections in the lower urinary tract. It effectively treats UTIs caused by bacteria like Klebsiella, Enterobacter cystitis, E. coli, Enterococcus, and Staphylococcus aureus. The way Nitrofurantoin works makes it quite a unique medication for treating UTIs.

When Nitrofurantoin is taken, the body absorbs it into the bloodstream, where it is quickly filtered out into the urine in the bladder. Deposited into the bladder, Nitrofurantoin combats and eliminates infectious bacteria at the site of the infection.

Nitrofurantoin is a prescription antibiotic that must be used as a qualified healthcare provider instructs explicitly to avoid unwanted complications or side effects. Nitrofurantoin is available under the Macrodantin, Nitro Macro, and Macrobid brand names.

Need an antibiotic prescription?

Get access to a licensed medical professional.

Is penicillin an antibiotic?

Penicillin is a class of antibiotics. Antibiotics are medications used to combat and eliminate bacterial infections. They usually kill bacteria or disrupt their reproduction so the body can naturally eliminate them. Antibiotics don’t work for diseases caused by viruses or other infectious agents, but they can be highly effective against bacteria.

Doctors usually prescribe certain antibiotics for specific infections. However, sometimes, they use antibiotics that can eliminate many different bacteria as a first-line treatment while waiting for test results that identify the particular bacteria.

It is important to use antibiotics as directed by a qualified healthcare professional. Antibiotics must be taken in the dose and manner that best treats the specific infection. If antibiotics are improperly used, bacteria can develop resistance, rendering the medication less effective.

Some side effects can occur with antibiotics. Some of these side effects include upset stomach, diarrhea, and, in women, vaginal yeast infections.

Antibiotics are grouped into classes based on their chemical structure. However, antibiotics within each class often affect the body differently and may be effective against different bacteria.

What is penicillin?

Penicillin is among the world’s first and most widely used antibiotic medications.

History of penicillin

Penicillin is culled from the Penicillium mold and was first noticed by Scottish bacteriologist Alexander Fleming in 1928.

Fleming saw that colonies of the bacterium Staphylococcus aureus failed to grow in areas accidentally contaminated by the green mold Penicillium notatum.

He isolated the mold, grew it in a fluid medium, and discovered that it produced a substance capable of killing many common bacteria that cause infections in humans.

Australian pathologist Howard Florey and British biochemist Ernst Boris Chain later purified penicillin in the late 1930s. By 1941, an injectable form of penicillin was available for therapeutic use.

Types of penicillin

There are two types of penicillin, which are divided into two groups: naturally occurring penicillins and semisynthetic penicillins.

Naturally occurring penicillins include penicillin V (phenoxymethylpenicillin) and penicillin G (benzylpenicillin). Penicillin G is given by intramuscular injection because it is poorly stable in acid. In contrast, penicillin V is administered orally and is typically more resistant to digestive acids.

Semisynthetic penicillins are altered forms of penicillin with improved properties. This class of penicillins includes aminopenicillins, antipseudomonal penicillins, and antistaphylococcal penicillins. Semisynthetic penicillins are more effective against a broader range of bacteria.

How does penicillin work?

Penicillins are highly effective against a wide range of bacteria. All penicillins work by disrupting the bacterial enzymes responsible for cell wall synthesis in reproducing microorganisms. Penicillin also triggers other enzymes to work on and break down the bacteria’s protective wall.

Penicillins were among the first drugs effective against bacterial infections caused by staphylococci and streptococci. However, extensive use has led to bacterial resistance.

Penicillin is a widely used antibiotic because it is effective against infectious bacteria. However, like any medication, penicillin can have side effects. There are essential points to note about penicillin and its side effects.

Penicillin can cause some common side effects. For instance, it may cause some people to experience nausea or vomiting. These common side effects affect 1 in 10 and 1 in 100 people.

Other common side effects include;

Abdominal discomfort


Skin rashes



Penicillin can also cause severe side effects. To avoid unwanted health complications, it is essential to use penicillin precisely as your doctor directs. Severe side effects occur in about 1 in 1000 people who are allergic to penicillin.

Penicillin can cause a life-threatening allergic reaction called anaphylaxis.

If you develop a red or itchy rash while taking penicillin, seek medical attention promptly.

You should also consider the following before using penicillin antibiotics.

Birth Control Pills: Penicillin V can make birth control pills less effective, potentially leading to pregnancy. Let your qualified medical expert know if you use birth control pills.

Complete Course: Take penicillin V the entire time your doctor prescribes, even if your symptoms ease. Incomplete treatment may not fully eradicate the infection.

Viral Infections: Penicillin V does not treat viral infections like the common cold or flu.

Avoid Sharing: Do not give this medication to another person, even if they have similar symptoms.

Is Nitrofurantoin a penicillin?

Is Nitrofurantoin a penicillin? Nitrofurantoin is not a penicillin antibiotic. Nitrofurantoin belongs to a class of antibiotics called nitrofurans, which treat urinary tract infections caused by bacteria.

Nitrofurans are effective against most gram-positive and gram-negative organisms that cause urinary tract infections. Nitrofurantoin is not related to other antibiotics like sulfa medicines.

How does Nitrofurantoin work?

Nitrofurantoin is commonly used to treat bacterial infections in the lower urinary tract. This medication is highly effective against bacteria that cause urinary tract infections, killing or preventing their growth.

Nitrofurantoin’s mechanism of action makes it a preferred choice for treating urinary tract infections. It is quickly filtered from the blood into the urine, and its antimicrobial agents eliminate the infectious bacteria at the site of the infection.

Nitrofurantoin side effects

Like most antibiotics, Nitrofurantoin can cause some side effects. These adverse effects range from mild to severe and common to rare. Some common side effects include the following:

Nausea: Feeling sick or vomiting.

Diarrhea: Changes in bowel movements.

Loss of Appetite: Reduced desire to eat.

Headaches: Mild to moderate head discomfort.

Dizziness or Sleepiness: Feeling lightheaded or tired.

Changes in Urine Color: Your urine may turn dark yellow or brownish. This is normal and not a reason to stop taking the medicine. Once you stop using Nitrofurantoin, your urine will return to its usual color.

Nitrofurantoin can cause some rare, severe side effects. These side effects occur in less than 1 in 1,000 people who use Nitrofurantoin. Some severe side effects include the following:

Lung Problems with symptoms like coughing up blood or mucus, shortness of breath, chest pain, or high temperature.

Liver or Gallbladder Disease: Pale stool, dark urine, yellowing of eyes or skin.

Blood Problems: Unexplained bruising, bleeding, sore throat, or fatigue.

Severe Headaches: Contact your doctor immediately if you experience severe headaches.

Warnings to note before using penicillin

Penicillin is a highly effective antibiotic, but it is vital to take some precautions to avoid unwanted health complications. Before using this medication, note the warnings.

People allergic to penicillin or other penicillin antibiotics such as carbenicillin, oxacillin, dicloxacillin, Amoxicillin, and ampicillin should not use penicillin. Let your doctor know if you’re allergic to cephalosporins or have a history of any allergy.

Patients with the following medical conditions should discuss with their healthcare professionals before using penicillin:

  • Kidney disease
  • Blood clotting disorder
  • Asthma
  • A history of diarrhea caused by antibiotics

Additionally, penicillin can make birth control pills less effective. Let your doctor know if you’re on birth control pills before using penicillin.

Take penicillin V the entire time your doctor prescribes, even if your symptoms improve. Complete the treatment to eliminate the infection.

In addition, penicillin does not treat infections caused by viruses or other organisms.

Antibiotic medicines can cause diarrhea. If you experience watery or bloody diarrhea, contact your doctor.

Please do not use any medicine to stop the diarrhea unless your doctor advises.

Remember to follow your doctor’s instructions and report any unusual symptoms promptly.

Warnings to note before using Nitrofurantoin

Nitrofurantoin is a highly effective antibiotic for UTI treatment, but it is vital to take some precautions to avoid unwanted health complications. Before using this medication, note the warnings.

Avoid Nitrofurantoin if you’re allergic or have the following health conditions:

  • Severe kidney issues
  • Difficulty urinating
  • A history of jaundice
  • Liver problems caused by using Nitrofurantoin
  • Inflammation of the lungs

If you experience chills, cough, fever, chest pain, or trouble breathing, seek medical attention promptly.

What drugs interact with Nitrofurantoin and penicillin?

All medications are likely to cause contraindications when combined with other drugs or substances. Nitrofurantoin and penicillin can cause some drug interactions when combined with other medicines.

Nitrofurantoin Interactions:

Nitrofurantoin interacts with various drugs. Some notable interactions include:

Local Anesthetics: Medications containing local anesthetics (such as procaine penicillin) may cause methemoglobinemia. This rare condition reduces the blood’s oxygen-carrying capacity, leading to oxygen deprivation in tissues and vital organs. The risk increases when combined with other medications that can also induce methemoglobinemia, like Nitrofurantoin.

Other Medications: Nitrofurantoin may interact with other drugs. Always consult your qualified healthcare expert before starting or stopping any medication.

Penicillin Interactions:

Penicillin antibiotics have a wide range of interactions. Here are some key points:

Severe Penicillin Allergy: Individuals with a severe penicillin allergy should avoid penicillins, cephalosporins, or other beta-lactam antibiotics.

Non-Severe Penicillin Allergy: Those with a non-severe penicillin allergy can avoid penicillins but may use cephalosporins, carbapenems, and other beta-lactams with caution (as the risk of cross-sensitivity is low).

Other Antibiotics: Nitrofurantoin, along with other antibiotics like amikacin, erythromycin, and ofloxacin, is considered safe for those with penicillin allergies.

Are Nitrofurantoin and penicillin safe to use while pregnant or breastfeeding?

Are Nitrofurantoin and penicillin suitable for pregnant or breastfeeding women? Both antibiotics are generally considered safe or use during pregnancy and breastfeeding. However, you must speak to your doctor before using any medication to avoid unwanted health complications.

Nitrofurantoin may be taken when pregnant, but it is generally best avoided in the third trimester. It could cause problems with a newborn’s red blood cells.

Most babies will not have this complication, but your healthcare expert may prescribe a different antibiotic if you are in the third trimester.

If your doctor says your newborn baby is healthy, you can take Nitrofurantoin while breastfeeding. Nitrofurantoin passes into breast milk in small quantities and is unlikely to cause adverse symptoms in your baby.

Doctors advise breastfeeding mothers to stay away from Nitrofurantoin if their baby has the following:

  • Jaundice
  • Glucose-6-phosphate dehydrogenase (G6PD) deficiency.

Read also: Is It Safe to Combine Nitrofurantoin and Ibuprofen?

Frequently Asked Questions

Nitrofurantoin is an antibiotic typically used to treat urinary tract infections caused by infectious bacteria. Nitrofurantoin belongs to the antibiotic class called Nitrofurans and is commonly prescribed to eliminate infectious diseases caused by bacteria in the lower urinary tract.

Nitrofurantoin is not a penicillin antibiotic. Other antibiotics in the penicillin class include the following:

  • Ampicillin
  • Carbenicillin
  • Dicloxacillin
  • Nafcillin
  • Oxacillin
  • Penicillin G
  • Penicillin V
  • Amoxicillin

Nitrofurans are a broad-spectrum class of antibiotics that are effective against most gram-positive and gram-negative organisms that cause urinary tract infections. furazolidone (FZD), nitrofurazone (NFZ), furaltadone (FTD), and nitrofurantoin (NFT).

Penicillins are a group of β-lactam antibiotics obtained initially from Penicillium molds. They inhibit bacterial growth and are used to treat various infections. Here are some common penicillin:

  • Penicillin G (Benzylpenicillin): Alexander Fleming accidentally discovered it in 1928. It is effective against gram-positive bacteria.
  • Penicillin V (Phenoxymethylpenicillin): Derived from the same mold as penicillin G, it is more acid-resistant and can be taken orally.
  • Ampicillin: A semisynthetic penicillin with broader activity against both gram-positive and gram-negative bacteria.
  • Amoxicillin: Another oral semisynthetic penicillin commonly used for various infections.
  • Methicillin: Used to treat staphylococcal infections, especially those resistant to other penicillin.

Additionally, antipseudomonal penicillins like piperacillin are effective against hard-to-treat gram-negative bacteria such as Pseudomonas and Klebsiella.

Nitrofurantoin and Amoxicillin are two different antibiotics in different classes. Amoxicillin is a type of penicillin antibiotic, while Nitrofurantoin is in the Nitrofuran class of antibiotics.

Amoxicillin is a penicillin medication used to treat various bacterial infections, including those of the middle ear, tonsils, throat, bronchi, lungs, urinary tract, and skin. It is also effective against H. influenzae, N. gonorrhea, and other bacteria.

Nitrofurantoin is generally used to treat urinary tract infections (UTIs) caused by various bacteria, including E. coli, Enterococcus, Klebsiella, and Staphylococcus aureus.

The content on Doctor Alexa’s blog is reviewed by Advanced practice registered nurses or pharmacist and is intended for educational purposes only. This information should not be relied upon as professional medical counsel. Be sure to always consult with your physician about the dangers and benefits of any medication, treatment or procedure.

You shouldn’t wait to see the doctor for simple health needs.