Can Nitrofurantoin Cause Anxiety?

Nitrofurantoin, one of the most commonly prescribed antibiotics for urinary tract infections, can cause neuropsychiatric side effects that include anxiety. A broad review of antimicrobial drugs found that neurotoxicity spans all classes of antibiotics, with effects ranging from headaches and anxiety to confusion, psychosis, and seizures. That said, anxiety as a direct side effect of nitrofurantoin is uncommon enough that teasing it apart from the stress of the infection itself takes some care.

What the Evidence Shows About Neuropsychiatric Effects

Nitrofurantoin has been in clinical use since the 1950s, and its most familiar side effects involve the gut and the lungs. But the drug does cross into territory that affects the brain and nervous system. A review of neurological and psychiatric adverse effects of antimicrobials placed anxiety on the spectrum of documented side effects across antibiotic classes, alongside depression, confusion, delirium, and seizures.¹ For nitrofurantoin specifically, the better-documented neuropsychiatric effects tend to be more severe than garden-variety anxiety. A published case report described an 86-year-old woman who developed auditory and visual hallucinations on the fifth day of nitrofurantoin therapy for a UTI. After ruling out other causes, clinicians concluded that nitrofurantoin was the likely trigger for her neuropsychiatric symptoms.²

That case is instructive because it shows that nitrofurantoin can clearly affect the central nervous system, even in a patient who had no prior history of psychiatric symptoms and no cognitive impairment. If a drug is capable of producing hallucinations and psychosis, it is biologically plausible that milder neuropsychiatric effects like anxiety, nervousness, or agitation could occur at lower intensities of the same mechanism. The trouble is that mild symptoms like these are underreported in the medical literature because patients and clinicians often attribute them to the infection, to general illness, or to the stress of being sick.

How Nitrofurantoin Might Affect the Nervous System

Nitrofurantoin works by damaging bacterial DNA and other cellular components, but it is not perfectly selective. Inside human cells, the drug undergoes a chemical reduction that produces what researchers call a nitro anion radical. This reactive molecule can kick off a chain of free-radical reactions and can also interact with compounds that regulate the cell’s oxidative balance.³ In plain terms, the drug creates oxidative stress inside cells, particularly in the mitochondria, which are the energy-producing structures that keep cells alive and functioning.

Nerve cells are especially sensitive to oxidative damage because they have high energy demands and limited ability to repair themselves. This is the same reason nitrofurantoin’s most well-known nervous system side effect is peripheral neuropathy, the tingling and numbness that typically starts in the feet and hands. The oxidative damage mechanism does not draw a clean line between peripheral nerves and the central nervous system. If enough of the drug or its reactive byproducts reach the brain, central effects like mood changes, confusion, or anxiety become possible.

Whether this actually happens often enough to worry about depends heavily on how much drug accumulates in the body, which brings us to who is most at risk.

Who Faces the Highest Risk

The single biggest risk factor for nitrofurantoin toxicity is impaired kidney function. Your kidneys are the main route for clearing nitrofurantoin from the blood. When kidney function drops, the drug lingers longer and at higher concentrations, which gives it more opportunity to damage nerve tissue. A New Zealand medicines safety bulletin noted that in patients with impaired renal function, the plasma concentration of nitrofurantoin increases and there is a higher risk of toxicity, including peripheral neuropathy.⁴

Interestingly, an older study in The American Journal of Medicine found that despite decreased urinary excretion, serum drug concentration did not necessarily increase in patients with renal failure in the way you might expect.⁵ This suggests the pharmacology is not as straightforward as “worse kidneys equals higher blood levels.” Other factors, like how the drug distributes into tissues or how quickly it is metabolized by the liver, may complicate things. Still, the clinical consensus reflected in prescribing guidelines around the world is that nitrofurantoin should be avoided or used cautiously in people with significantly reduced kidney function.

Older adults face a double risk. Age-related decline in kidney function is extremely common and is frequently undiagnosed. The 86-year-old patient in the hallucination case report is a clear example: she was immunocompetent with normal baseline cognition, yet developed dramatic psychiatric symptoms within days of starting the drug.² Older adults are also more likely to be taking other medications that affect the nervous system, which could amplify any neuropsychiatric effects nitrofurantoin produces on its own.

When the Infection Itself Causes the Anxiety

Here is where the picture gets genuinely murky. Urinary tract infections themselves produce a substantial amount of emotional distress. Pain, urgency, disrupted sleep, worry about recurrence, and the general experience of feeling unwell can all produce or worsen anxiety. If you start an antibiotic and also feel anxious, it is natural to blame the pill. But the infection you are treating was already doing a number on your mental state before you swallowed the first dose.

This is especially true for people who experience recurrent UTIs. The cycle of infection, treatment, brief relief, and re-infection is psychologically grinding. Anxiety about whether the infection will come back, about whether the antibiotic will work, and about potential side effects creates a feedback loop that can make any physical sensation during treatment feel more ominous than it is.

On the other hand, some people report that their anxiety starts abruptly a day or two into a nitrofurantoin course and resolves within a day or two of stopping it. That temporal pattern, where symptoms appear after starting the drug and disappear after stopping, is the strongest informal evidence that the drug itself is involved. It is not proof, because the placebo effect and the natural course of the infection can both produce similar timing. But if you notice a clean on-off pattern, especially across more than one course of nitrofurantoin, it is worth taking seriously and mentioning to your prescriber.

Pulmonary Side Effects That Mimic Anxiety

One underappreciated angle here is that nitrofurantoin’s best-documented serious side effect, lung toxicity, can produce symptoms that feel a lot like an anxiety attack. Acute pulmonary toxicity from nitrofurantoin typically shows up as a hypersensitivity reaction in the lungs, with fever, shortness of breath, and a general feeling of being unwell.⁶ If you are suddenly short of breath and your heart rate is climbing, the subjective experience can be indistinguishable from a panic attack, especially if you have never had a lung problem before and your mind reaches for the most familiar explanation.

This matters because misidentifying a pulmonary reaction as “just anxiety” could delay getting the help you need. The acute lung reaction is generally reversible once nitrofurantoin is stopped, but continuing the drug makes things worse. A chronic form of pulmonary toxicity, which develops over weeks to months of use, is more insidious and harder to reverse. If you develop new shortness of breath, chest tightness, or a dry cough while taking nitrofurantoin, do not write it off as anxiety. Get it checked.

How Duration and Dose Factor In

Nitrofurantoin is most commonly prescribed as a short course, typically five to seven days, for an uncomplicated UTI. At that duration and at standard doses, neuropsychiatric side effects are unusual. The risk profile shifts when the drug is used for longer periods. Some people take low-dose nitrofurantoin for months as prophylaxis against recurrent UTIs. With prolonged use, the cumulative exposure to oxidative stress goes up, and the chance of peripheral neuropathy increases substantially. Whether that extended exposure also raises the risk of central nervous system effects like anxiety is less clear from the published literature, but the underlying biology points in that direction.

If you are on long-term nitrofurantoin and notice new or worsening anxiety, nervousness, or mood changes, those symptoms are worth flagging to your doctor. They are not a reason to stop the drug on your own without talking to someone first, because abruptly stopping a prophylactic antibiotic could trigger a rebound UTI, but they are a reason to have a conversation about whether the drug is the best option for you going forward.

What to Do If You Suspect Nitrofurantoin Is Causing Anxiety

The first step is to note the timeline. When did the anxiety start relative to when you started nitrofurantoin? Did it appear within the first few days? Was it a kind of anxiety you had not experienced before, or a worsening of something you already had? If the timing lines up and the feeling is new, that is useful information for your clinician.

Do not stop the antibiotic without medical guidance. Incomplete antibiotic courses can lead to resistant infections, and a UTI that is not adequately treated can itself become a more serious problem. Instead, contact your prescriber and describe what you are experiencing. In most cases, there are alternative antibiotics for UTIs. Trimethoprim-sulfamethoxazole and fosfomycin are common alternatives, and they have their own side-effect profiles but may not produce the same neurological effects in a given person.

If you have taken nitrofurantoin before without problems and the anxiety feels more like a background hum than something new and sharp, the infection itself is a more likely culprit. Treating the UTI effectively will probably resolve the anxiety as the pain, discomfort, and sleep disruption improve.

Peripheral Neuropathy as a Warning Signal

While anxiety on its own may be hard to attribute confidently to nitrofurantoin, peripheral neuropathy is a well-established side effect. If you notice tingling, numbness, or a burning sensation in your hands or feet while on nitrofurantoin, that is a red flag that the drug is affecting your nervous system. In that context, co-occurring anxiety or other mood changes become more plausible as drug effects rather than coincidence.

Peripheral neuropathy from nitrofurantoin can be irreversible if the drug is continued too long after symptoms start, so the standard guidance is to stop the drug promptly if neuropathy symptoms appear.⁴ If you already have neuropathy from another cause, such as diabetes, you are likely to be more susceptible. Many prescribers avoid nitrofurantoin entirely in people with pre-existing neuropathy for this reason.

Why This Side Effect Is Hard to Study

Anxiety as a drug side effect is notoriously difficult to pin down in clinical research. It is subjective, highly variable, and influenced by dozens of confounding factors. A clinical trial measuring whether nitrofurantoin causes anxiety would need to separate the drug’s effect from the anxiety of having a UTI, the anxiety of being in a study, baseline anxiety levels, and any concurrent medications. These trials essentially do not exist for nitrofurantoin and anxiety specifically. What we have instead are case reports, pharmacovigilance databases where patients and clinicians voluntarily report suspected side effects, and broader reviews of antibiotic neurotoxicity.

The pharmacovigilance data is tricky because it relies on people recognizing a symptom as a potential side effect and then going through the trouble of reporting it. Mild anxiety is exactly the kind of symptom that falls through the cracks. Someone who develops dramatic hallucinations on nitrofurantoin will end up in a case report. Someone who feels a bit more on edge than usual for five days probably will not report it to anyone. This means the true rate of nitrofurantoin-associated anxiety is likely higher than what appears in the medical literature, though we have no good way to estimate by how much.

Antibiotics and Mental Health More Broadly

Nitrofurantoin is not unique in its potential to affect mood and cognition. Across antibiotic classes, neuropsychiatric effects are a recognized category of adverse reactions.¹ Fluoroquinolones like ciprofloxacin and levofloxacin carry FDA black-box warnings for central nervous system effects including anxiety, insomnia, and confusion. Metronidazole has been linked to depression and irritability. Even common penicillins have rare case reports of psychiatric symptoms.

This does not mean antibiotics are inherently dangerous to your mental health. These effects are uncommon, and for most people, the benefits of treating a bacterial infection far outweigh the small risk of a neuropsychiatric side effect. But it does mean that if you notice a clear mental-health change during any antibiotic course, you should not dismiss it as impossible. The biology supports it: antibiotics are powerful drugs that interact with human physiology in ways that go well beyond killing bacteria, including through oxidative stress, changes to the gut microbiome, and direct effects on neurotransmitter systems. The specific pathway varies by drug class, but the general principle holds.

For nitrofurantoin, the oxidative stress mechanism in mitochondria is the most studied pathway for neurotoxicity.³ Whether that same mechanism explains mild symptoms like anxiety or only accounts for more dramatic effects like neuropathy and psychosis is an open question. The honest answer is that we do not know the exact threshold at which oxidative damage to nerve cells starts producing subjective mood changes. It probably varies considerably from person to person based on genetics, kidney function, age, and what else is going on in the body at the time.