The Unsettling Truth About Ciprofloxacin: A Wonder Drug’s Darker Side

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In July 2023, Lara Martin visited the emergency room in Humboldt County, California, with what she suspected was a urinary tract infection. Martin, who had been treated for a more severe UTI years earlier, was worried the infection might spread to her kidneys if she waited to get it treated. The emergency room doctor confirmed that the source of her discomfort was a UTI and prescribed an antibiotic called ciprofloxacin.

After the doctor left the room, a nurse mentioned to Martin that doctors sometimes prescribe very strong antibiotics just to be on the safe side. The comment struck Martin as odd until she picked up the prescription and read a warning about serious side effects on the label.

Concerned, she called her mother, a former nurse, to confirm that ciprofloxacin was safe for her to take.

“Oh, don’t worry about it,” Martin recalled her mother saying. “They’ve been prescribing that stuff for 30 years.”

The next day, Martin was moving heavy pallets at work when she noticed on her smartwatch that her heart rate was plummeting. Fearing it might be related to the antibiotics, she called the emergency room medical team, who also told her not to worry. Despite the troubling drop in her heart rate and a growing sense of unease, Martin followed the doctor’s orders and took the full course of antibiotics.

Six weeks after she finished taking ciprofloxacin, Martin was too weak to leave the house.  Chronic fatigue and brain fog clouded her judgment. Nerve pain left her feeling debilitated and depressed. She took a leave from work and enrolled in California’s temporary disability program.

“I loved my job, I loved my life,” Martin recalls.

More than a year later, her symptoms still haven’t improved.

Ciprofloxacin: A Breakthrough Antibiotic With Serious Side Effects

Ciprofloxacin was approved by the FDA in 1987 as the latest addition to the class of antibiotics known as fluoroquinolones. Doctors hailed it as a breakthrough — a broad-spectrum antibiotic capable of treating both routine and resistant bacterial infections. In 1989, U.S. doctors wrote 5 million prescriptions of ciprofloxacin, or one for every 49 Americans.

This enthusiasm quickly spiraled out of control.

The following year, a series of case reports published in the Journal of the American Medical Association warned of inappropriate prescribing practices. Researchers suggested that doctors were frequently recommending ciprofloxacin for ailments that didn’t warrant its use, such as sore throats and sinus infections, and, in some cases, were even giving it to patients with no confirmed infection at all.

In 2008, the Food and Drug Association (FDA) issued a “black box” warning for ciprofloxacin, a warning that is typically reserved for medications that may have serious or even fatal side effects. In the initial warning, the FDA emphasized the possibility of tendon rupture, but in 2016, the agency expanded its warning to include nerve damage, gastrointestinal distress, and mental health issues, including anxiety, depression and suicidal thoughts.

While study data show that fluoroquinolone use began declining after the FDA updated its warning about the medication in 2016, ciprofloxacin — also known as Cipro — still remains one of the most commonly prescribed antibiotics in the U.S. Doctors wrote 450,000 prescriptions of ciprofloxacin for Medicare patients in California alone in 2022, the most recent year for which data is available. The HHS estimates that 2.6 million prescriptions were written nationally that year. As for fluoroquinolones as a whole, the Centers for Disease Control (CDC) reported 14.7 million prescriptions in 2023.

Ciprofloxacin remains a critical antibiotic for more severe and complex infections, such as bacterial pneumonia, anthrax exposure, and complicated urinary tract infections, but doctors should exhaust other options before turning to it, says Ashley Cubillos, PharmD, an antimicrobial stewardship clinical pharmacist with Banner Health in Greeley, Colorado.

“Prescribers have gotten to view fluoroquinolones as a solution to maybe any and all infectious problems,” she says.

“Floxies” Want You To Know Fluoroquinolone-Associated Disability Is Real

Martin suspects that she has fluoroquinolone-associated disability, the medical term for people who experience two or more serious side effects lasting at least 30 days after they stop taking fluoroquinolones.

These serious adverse side effects, which include Achilles tendon rupture and aortic aneurysms, are considered uncommon, affecting fewer than 1 in 100 people in the U.S. However, experts caution that these adverse reactions remain poorly understood — and may be underreported.

People with fluoroquinolone-associated disability often say they have been “floxed.” The Reddit page for “floxies” has 5,700 members and a similar Facebook page has 9,300, including Martin. People post constantly, describing their experiences with excruciating pain, torn ligaments, impaired vision, severe weight loss, and other serious side effects they say are linked to fluoroquinolones.

Ciprofloxacin Is Meant for Complicated UTIs. So Why Do Doctors Still Prescribe It for Uncomplicated Ones?

Although ciprofloxacin can treat various infections, UTIs are one of the primary use cases. As many as 60 percent of American women will contract a UTI in their lifetime, with the risk increasing in women over 65. In older individuals and people with underlying health conditions, these infections can be more persistent, and are called “complicated” UTIs. “Uncomplicated” UTIs occur in the absence of complicating factors and generally respond well to antibiotics such as Bactrim (sulfonamide class) and Macrobid (nitrofuran class), which are less likely to cause severe side effects.

According to the FDA, ciprofloxacin should be reserved for complicated UTIs, or when these other antibiotics have failed.

But some doctors, like the physician who treated Lara Martin, still prescribe ciprofloxacin for uncomplicated cases.

The symptoms of a UTI are often obvious and very uncomfortable, prompting many people to rush to urgent care or an outpatient clinic when their symptoms start. The doctor will collect a urine sample and send it to a lab, where scientists will identify which bacteria are present in the sample. On average, the process takes two to three days, during which a mild infection could become more serious without treatment. For that reason, doctors usually prescribe antibiotics before they have results.

Eric Hansen, D.O., a physician practicing in Hesperia, a town in San Bernardino County, was one of California’s top ciprofloxacin prescribers for Medicare patients in California in 2021. When contacted about his ciprofloxacin prescribing habits, Dr. Hansen, who primarily treats older adults, explained that he has made an effort to cut back on prescribing the drug after seeing reports of its harmful side effects, but maintains that it remains necessary in certain cases — especially when dealing with older adults.

Ciprofloxacin is available in pill form and requires just a one-week course, notes Dr. Hansen, making it more convenient for patients than first-line drugs for uncomplicated UTIs. Some alternative treatments for complex infections require intravenous administration or extended treatment durations, which can be challenging for older patients to complete, he adds.

“It’s going to be a real problem if they decide that the complications of Cipro mean that we need to pull that drug,” says Dr. Hansen. “The alternatives really are limited. I don’t know what the heck I would do otherwise.”

None of his patients have reported adverse side effects from ciprofloxacin, notes Dr. Hansen, but he sometimes receives calls from patients with concerns about the drug’s possible side effects. Occasionally, he swaps out the antibiotic for a different drug. But in many cases, he argues, there is no better alternative.

The Full Scope of Ciprofloxacin’s Side Effects Remains Unclear

In 2020, Aaron Preacher, a children’s television writer who lives in the foothills of Los Angeles, visited the doctor due to persistent stomach pain. His doctor scheduled a colonoscopy and prescribed him ciprofloxacin to take in the meantime.

Unlike Martin, Preacher did not have a confirmed infection when prescribed the antibiotic.

“They just wanted to make sure that there was nothing wrong,” explains Preacher.

He doesn’t recall any mention of potential risks.

But after taking a few doses, Preacher noticed a tingling sensation spreading up his legs, leaving him numb below the knee. He searched his symptoms and “cipro” online and that’s when he discovered the side effects. He stopped taking the drug right away, but the symptoms continued to progress.

As his daughter took her first steps, Preacher himself struggled to walk. Horrible cramps awoke him in the middle of the night, and he felt his muscles and tendons throbbing. He suffered from bouts of debilitating nerve pain and had difficulty using his hands and legs.

A doctor referred Preacher to a rheumatologist, who was dismissive when Preacher suggested that his condition could be related to ciprofloxacin. After running an extensive panel of tests, the rheumatologist could not offer a diagnosis.

The FDA has acknowledged fluoroquinolone-associated disability as a condition, but it is neither well understood nor widely studied. Researchers have hypothesized that floxing is the result of damage to mitochondria, the structures in our cells that generate energy from glucose.

“It seems like a puzzle that we just started getting out of the box, and we haven’t even gotten all the pieces out yet,” says Cecilia Bove, Ph.D., a biologist at York College of Pennsylvania, who studies the long-term effects of fluoroquinolones on the digestive system.

As for Preacher, he has regained some mobility and now tries to walk around 5,000 to 8,000 steps per day. Recently, his daughter asked if they could go to the beach when his legs feel better.

“I just want a doctor to fix this,” he says.

Reining in Cipro: The Effort to Change Prescribing Habits

While Bove and other researchers try to figure out why ciprofloxacin can have such serious side effects, specialists in antibiotics are working on ways to discourage its frequent use.

David Hyun, M.D., the director of the antibiotic resistance project at the Pew Charitable Trusts, notes that showing doctors their high prescription rates of risky drugs the data is often enough to elicit changes.

But that’s easier to execute in a large hospital than a primary care clinic, where most ciprofloxacin prescriptions are written.

“A good majority of the fluoroquinolones currently being prescribed are happening in the outpatient setting, and that’s why we’re still seeing high numbers,” explains Dr. Hyun.

It’s not impossible to change primary care doctors’ prescribing behavior, however. A 2022 study conducted in Florida by Banner Health’s Cubillos and colleagues described an antimicrobial stewardship program that reduced how often fluoroquinolones were prescribed for UTIs from 18 percent of the time to 3 percent in urgent care clinics and from 23 percent to 7 percent in primary care clinics.

The strategy was simple: They modified the health system’s list of recommended antibiotics that doctors reference when writing prescriptions to deprioritize fluoroquinolones and recommend other drugs first. They also gave prescribers information about their prescribing habits and fluoroquinolones’ adverse effects.

Cubillos says it can be difficult for a healthcare practice to know if it is prescribing too many fluoroquinolones, because there are no established standards for how often ciprofloxacin should be prescribed.

“Ultimately, the doctors or the prescribers are always responsible,” says Hyun. “That’s what it always boils down to.”

A Potential Alternative And A Doctor’s Responsibility

In October 2024, the FDA approved a new oral carbapenem antibiotic called Orlynvah for treating uncomplicated UTIs. The pharmaceutical company Iterum Therapeutics first petitioned for its approval three years earlier, but the FDA rejected the application, citing concerns about efficacy after it failed to outperform ciprofloxacin. Orlynvah was approved after a second trial demonstrated that it works better than the antibiotic Augmentin, an alternative to ciprofloxacin.

Todd Purves, M.D., a pediatric urologist at Duke Health who tries to avoid prescribing ciprofloxacin to his young patients, says Orlynvah won’t replace the drug—but it could offer another option.

“We really leaned on [cirpofloxacin] for a long time,” explains Dr. Purves.

While Orlynvah provides another tool against antibiotic-resistant infections, it comes with its own set of side effects, he notes.

So far, the side effects described are similar to those caused by other UTI medications, such as nausea, headache and vaginal yeast infection.

Regardless of the drug, responsible use is crucial to protecting patients and preserving the efficacy of the antibiotic. Using antibiotics in situations they aren’t recommended for drives up rates of antibiotic resistance.

“That’s a problem with antibiotic stewardship in general,” notes Dr. Purves. “The best antibiotic is going to be abused most.”

As Martin’s nurse pointed out when she sought treatment for her UTI two years ago, a strong antibiotic is often seen as the safer choice over one that might be ineffective. In outpatient care, where providers may never see a patient again, the priority is certainty—often at the expense of tracking potential side effects.

Maryrose Laguio-Vila, M.D., an infectious disease physician at Rochester Regional Health in New York, calls it an “incomplete feedback loop.” If the prescriber doesn’t hear about side effects, they might not understand the risks.

Preacher, who is still managing his symptoms years after taking ciprofloxacin, is much more wary of medications than he once was. He always does his homework, but doesn’t believe this is the duty of a patient.

“The responsibility should rest with the doctors and pharmacists,” he says. “To stay current and routinely reevaluate the powerful chemicals they prescribe daily.”

[Additional writing and reporting by Madeline Reinsel and Gillian Dohrn]