Learn about Macrodantin drug interactions, including medications, supplements, and foods to watch out for. Know what to tell your doctor before starting Nitrofurantoin.
Before starting any new medication, it's important to understand how it interacts with other drugs, supplements, and foods you're already using. Macrodantin (Nitrofurantoin) is generally a well-tolerated antibiotic with fewer drug interactions than many other medications — but there are still some combinations you need to watch out for.
This guide covers the major and moderate drug interactions for Macrodantin so you can have an informed conversation with your doctor and pharmacist.
Drug interactions happen when one substance changes the way another works in your body. This can happen in several ways:
With Macrodantin specifically, the most important interactions involve drugs that affect its absorption, its concentration in urine (where it does its work), or that increase the risk of liver damage.
These interactions are the most clinically significant. You should avoid these combinations or discuss them carefully with your doctor:
Antacids that contain magnesium trisilicate can significantly reduce how much Nitrofurantoin your body absorbs. This means the drug may not reach effective levels in your urine, and your UTI may not clear up. If you need an antacid while taking Macrodantin, ask your pharmacist to recommend one that does not contain magnesium trisilicate.
Probenecid (used for gout) interferes with Macrodantin in a double-negative way: it increases Nitrofurantoin levels in your blood (raising toxicity risk) while simultaneously reducing the drug's concentration in your urine. Since Macrodantin only works in the urine, this combination makes the medication both less effective and more dangerous. This combination should generally be avoided.
Sulfinpyrazone (another gout medication) has a similar effect to Probenecid — it can increase blood levels of Nitrofurantoin while decreasing urinary concentration. The same risks apply.
Pexidartinib is a medication used for certain tumors. Both Pexidartinib and Macrodantin can cause liver damage, and taking them together significantly increases the risk of hepatotoxicity. This combination should be avoided. If you're taking Pexidartinib and develop a UTI, your doctor should prescribe a different antibiotic.
These interactions are less severe but still worth discussing with your doctor:
Nitrofurantoin may antagonize (work against) the antibacterial effect of quinolone antibiotics like Norfloxacin in the urinary tract. If your doctor is considering a quinolone antibiotic for your UTI, they should generally choose one or the other — not both. This doesn't apply to all quinolones equally, but it's something your prescriber should be aware of.
Like most antibiotics, Macrodantin may reduce the effectiveness of live bacterial vaccines, specifically the BCG vaccine (used for tuberculosis and sometimes bladder cancer treatment). If you're scheduled to receive a live vaccine, let your healthcare provider know you're taking an antibiotic so they can adjust the timing if needed.
Diphenoxylate/Atropine is an anti-diarrheal medication. It slows down your digestive tract, which can increase how much Nitrofurantoin your body absorbs. This could potentially raise blood levels and increase the risk of side effects. If you're experiencing diarrhea while on Macrodantin, talk to your doctor before using Lomotil — they may recommend a different approach.
While Macrodantin has relatively few interactions with supplements and OTC products, there are a few things to keep in mind:
As mentioned above, antacids containing magnesium trisilicate should be avoided. Other antacids (calcium carbonate, aluminum hydroxide) don't have the same interaction, but it's still a good idea to separate them from your Macrodantin dose by at least two hours to be safe.
Cranberry juice and supplements are commonly used for UTI prevention. There's no known interaction with Macrodantin, and you can safely continue using cranberry products while taking the medication. Just don't rely on cranberry alone to treat an active UTI — it's not a substitute for antibiotics.
Probiotics are generally safe to take alongside Macrodantin and may even help reduce antibiotic-related digestive side effects like diarrhea. Space your probiotic dose a few hours apart from your antibiotic for the best results.
There's no established major interaction between Nitrofurantoin and iron supplements, but high-dose iron can cause stomach upset on its own. If you're taking both, taking them at different times of day may help reduce GI discomfort.
Unlike many medications, food is actually recommended with Macrodantin. Taking it with a meal improves absorption and significantly reduces nausea and stomach upset. There are no specific foods you need to avoid.
There is no direct chemical interaction between Nitrofurantoin and alcohol — unlike some antibiotics (like Metronidazole), Macrodantin won't cause a severe reaction if you drink. However, alcohol can:
Most doctors recommend avoiding or limiting alcohol while taking any antibiotic. It won't cause a dangerous reaction with Macrodantin, but it's not helping your recovery either.
Before your doctor prescribes Macrodantin, make sure they know about:
Your pharmacist is also an excellent resource. When you pick up your prescription, they'll check for interactions with your other medications. Don't hesitate to ask them if you have questions about combining Macrodantin with anything else you're taking.
For more information about Macrodantin's side effects and safety, read our side effects guide. To learn about the medication itself, see What Is Macrodantin?.
Macrodantin has relatively few drug interactions compared to many other antibiotics — which is one of its advantages. The most important interactions to be aware of involve gout medications (Probenecid, Sulfinpyrazone), certain antacids (magnesium trisilicate), and medications that increase liver toxicity risk (Pexidartinib).
The golden rule: always give your doctor and pharmacist a complete list of everything you're taking. They'll catch any potential interactions and help you take Macrodantin safely and effectively.
Need help finding Macrodantin at a pharmacy near you? Medfinder can help you check availability and compare prices.
You focus on staying healthy. We'll handle the rest.
Try Medfinder Concierge FreeMedfinder's mission is to ensure every patient gets access to the medications they need. We believe this begins with trustworthy information. Our core values guide everything we do, including the standards that shape the accuracy, transparency, and quality of our content. We’re committed to delivering information that’s evidence-based, regularly updated, and easy to understand. For more details on our editorial process, see here.
%2C%20Color%3DOriginal.png)
