Does Nitrofurantoin Have Sulfa?

Those with allergies to medicines often have to be aware of other medications they can be allergic to because of shared ingredients. Concerns such as this may cause someone with a sulfa allergy to wonder if they can take nitrofurantoin. 

Nitrofurantoin does not belong to the sulfa class of antibiotics and therefore does not contain any sulfa compounds, making it a safe option for individuals with allergies to sulfa drugs.

However, there are other considerations to be aware of with nitrofurantoin, continue reading to learn more. 

Key Takeaways:

  • Nitrofurantoin does not belong to the sulfa class of antibiotics.
  • Some people may be sensitive to sulfates, which are not the same as sulfa drugs.
  • Nitrofurantoin does not contain any sulfa compounds.
  • It is safe for individuals with sulfa allergies to take nitrofurantoin.
  • Nitrofurantoin allergies also exist, so anyone experiencing an allergic reaction should seek immediate medical attention. 

Table of Contents

What Is Nitrofurantoin?

Nitrofurantoin is an antibiotic prescribed for bacterial infections, especially urinary tract infections. It is only available as an oral antibiotic and has the brand names Macrobid, Macrodantin, or Nitro Macro. 

Nitrofurantoin treats bacterial infections by keeping bacteria from producing the DNA, RNA, and cell wall proteins they need to survive. 

Can You Take Nitrofurantoin if You Have a Sulfa Allergy?

Nitrofurantoin is not a sulfa drug, so it is safe for those with a sulfa allergy to take. 

Sulfa allergies refer to allergic reactions to “sulfa drugs,” or antibiotics belonging to the sulfonamide class, which includes sulfasalazine, acetazolamide, and sulfisoxazole. 

Sulfa drugs work differently than nitrofurantoin; their mechanism of action involves inhibiting a specific enzyme, dihydropteroate synthase (DHPS), which produces folic acid in bacteria. Folic acid is needed for the bacteria to proliferate, so they cannot grow or multiply when the enzyme is inhibited.

In comparison, nitrofurantoin belongs to the nitrofuran antibiotic class and contains no sulfa. 

Are There Any Risks of Taking Nitrofurantoin When Allergic to Sulfa?

There are no risks of taking nitrofurantoin when allergic to sulfa. However, while nitrofurantoin does not contain sulfa, some varieties may contain sulfates. 

Despite having similar names, which can cause many people to think there is a connection between sulfa and sulfates, these allergies are not the same. Still, some people with a sulfa allergy may also be allergic (or sensitive) to sulfates, but there is no connection between these two allergies, and most people with sulfa allergies are safe to consume sulfates. 

It is also important to remember that nitrofurantoin allergies are also possible, although not connected to sulfa allergies. This means that just because you have a sulfa allergy does not mean you are more likely to have a nitrofurantoin allergy. Still, allergies to nitrofurantoin may present with hives, difficulty breathing, and swelling of the face, mouth, and throat. If you experience any of these symptoms while taking Macrobid, seek immediate medical attention. 

When to See a Doctor?

If you ever experience symptoms of an allergic reaction while taking nitrofurantoin, seek medical attention. Furthermore, if you’re ever curious about whether it is safe to take a medication due to a previous allergy, sulfa, or otherwise, always contact your doctor to inquire about this. 

In addition to allergies, those taking nitrofurantoin should speak to a doctor if they have:

  • sudden chest pain or discomfort
  • watery or bloody diarrhea
  • numbness, pain, or tingling in the hands or feet
  • new or worsening cough
  • wheezing
  • difficulty breathing
  • lupus-like syndrome (swollen glands, vomiting, joint swelling or pain accompanied by fever, patchy skin color, muscle aches, unusual thoughts or behavior)
  • liver problems (upper stomach pain, loss of appetite, itching, nausea, clay-colored stools, jaundice, dark urine)

In Conclusion

Nitrofurantoin is an antibiotic belonging to the nitrofuran antibiotic class and is prescribed to treat urinary tract infections because of its ability to collect in the bladder. As a nitrofuran drug, nitrofurantoin does not belong to the sulfa class of antibiotics and, as such, is safe for those with a sulfa allergy to take. 

Some people may be sensitive to sulfates, which nitrofurantoin does contain, but despite similar names, this is not connected to sulfa allergies. Furthermore, it is also possible to have a nitrofurantoin allergy, so anyone who experiences signs of an allergic reaction should seek medical attention. 

Key Takeaways:

  • Nitrofurantoin does not belong to the sulfa class of antibiotics and is safe for those with a sulfa allergy.
  • Some people may be sensitive to sulfates, which are not the same as sulfa drugs, but which nitrofurantoin does contain. 
  • Nitrofurantoin allergies also exist, so anyone experiencing an allergic reaction should seek immediate medical attention. 


  • Squadrito FJ, del Portal D. Nitrofurantoin. [Updated 2023 May 29]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from:
  • McGarry, M. R., Wagner, M. W., & Wall, B. M. (2021). Systemic Inflammatory Response Syndrome Secondary to Nitrofurantoin. Journal of investigative medicine high impact case reports, 9, 2324709620984610. 
  • Malik, R. D., Wu, Y. R., Christie, A. L., Alhalabi, F., & Zimmern, P. E. (2018). Impact of Allergy and Resistance on Antibiotic Selection for Recurrent Urinary Tract Infections in Older Women. Urology, 113, 26–33. 
  • Dorn, J. M., Alpern, M., McNulty, C., & Volcheck, G. W. (2018). Sulfonamide Drug Allergy. Current allergy and asthma reports, 18(7), 38. 
  • Ponka D. (2006). Approach to managing patients with sulfa allergy: use of antibiotic and nonantibiotic sulfonamides. Canadian family physician Medecin de famille canadien, 52(11), 1434–1438, PMID: 17279201.
  • Dibbern, D. A., Jr, & Montanaro, A. (2008). Allergies to sulfonamide antibiotics and sulfur-containing drugs. Annals of allergy, asthma & immunology : official publication of the American College of Allergy, Asthma, & Immunology, 100(2), 91–111. 

Content on the DrHouse website is written by our medical content team and reviewed by qualified MDs, PhDs, NPs, and PharmDs. We follow strict content creation guidelines to ensure accurate medical information. However, this content is for informational purposes only and not a substitute for professional medical advice, diagnosis, or treatment. For more information read our medical disclaimer.

Always consult with your physician or other qualified health providers about medical concerns. Never disregard professional medical advice or delay seeking it based on what you read on this website.

If you are experiencing high fever (>103F/39.4C), shortness of breath, difficulty breathing, chest pain, heart palpitations, abnormal bruising, abnormal bleeding, extreme fatigue, dizziness, new weakness or paralysis, difficulty with speech, confusion, extreme pain in any body part, or inability to remain hydrated or keep down fluids or feel you may have any other life-threatening condition, please go to the emergency department or call 911 immediately.



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