A rare reaction to fluoroquinolone antibiotics turned John Marshall’s life upside down.

John Marshall, a 51-year-old from Kirkcaldy, was once an avid runner. Today, he struggles to walk after a severe and life-changing reaction to a group of antibiotics called fluoroquinolones, prescribed to him in 2017.

The impact on his body was swift and devastating. Within days of starting the medication, John experienced excruciating joint pain. “Every joint was sore—fingers, elbows, toes, ankles—everything,” he recalls. “It was stabbing pains, jumping pains. My muscles were twitching uncontrollably.”

John is one of a growing number of patients who say they have been “floxed,” a term coined by campaigners raising awareness about the rare but severe side effects of fluoroquinolones. These antibiotics, which include ciprofloxacin and levofloxacin, are powerful tools against specific bacterial infections. However, their use carries the risk of potentially irreversible complications, including tendon ruptures, nerve damage, and even mental health issues.

Seven years after his ordeal began, John still lives with chronic pain and relentless muscle spasms. At night, his legs lock up so painfully that he has to use one leg to force the other straight. “It’s that level of pain,” he says, describing how the condition has upended his life.

John’s nightmare began after he was prescribed the drugs in the hospital to treat a serious infection following a vasectomy. He reported joint pain to his GP shortly after, only to be told the symptoms would subside once he stopped the antibiotics. They didn’t. Two years later, an MRI revealed he had a ruptured bicep tendon—a spontaneous injury requiring surgery to reattach the tendon.

“I just woke up one morning with a painful shoulder,” John recalls. “I hadn’t moved, lifted anything, or been exercising. For three months, I had to sleep sitting up. These drugs have caused huge issues in my life.”

New guidelines issued nearly a year ago by the UK’s Medicines and Healthcare Products Regulatory Agency (MHRA) have called for fluoroquinolones to be used only in cases where alternative antibiotics are unsuitable. The MHRA strengthened warnings about the drugs’ rare but severe side effects, which include tendon damage, nerve pain, and mental health risks such as suicidal thoughts.

Despite the guidance, experts warn that over-prescription remains a problem. Professor Neal Millar, a leading specialist in fluoroquinolone toxicity based at the University of Glasgow, says awareness among doctors is still lacking. “The message about overuse is not getting through to GPs and other prescribers,” he says.

Prof Millar, who has treated around 1,000 patients for fluoroquinolone-associated disabilities, says his clinic is busier than ever. “Prescribing rates are down, but the volume of people affected remains significant,” he adds.

In Scotland, fluoroquinolones accounted for 2.4% of total antibiotic prescriptions in 2023. While the number of daily doses has dropped by nearly 20% over four years, thousands of people still take these medications annually.

For John, the damage is done. “These drugs have had a catastrophic impact on my health,” he says. Once a man who thrived on physical activity, he now navigates life with pain as his constant companion. His story, like those of many others, underscores the urgent need for cautious prescribing and greater awareness of the potential dangers of these powerful medications.