The U.S. Food and Drug Administration (FDA) just announced a labeling update for fluoroquinolone antibacterial drugs. Used to treat bacterial infections, fluoroquinolones can cause disabling and sometimes permanent side effects in the tendons, muscles, joints, nerves, and central nervous system. These side effects can occur hours to week after taking fluoroquinolones.

The FDA believes “the risk of these serious side effects generally outweighs the benefits” for patients who are only suffering from acute bacterial infections, and that fluoroquinolones should be reserved for patients who have no other alternatives.

The FDA still believes the benefits of fluoroquinolones outweigh the risks in patients who are suffering from serious bacterial infections like anthrax, plague, and bacterial pneumonia.

FDA-approved fluoroquinolones include levofloxacin (Levaquin), ciprofloxacin (Cipro), ciprofloxacin extended-release tablets, moxifloxacin (Avelox), ofloxacin, and gemifloxacin (Factive). The FDA estimates approximately 22 million patients received a prescription for at least one type of fluoroquinolone in 2014 alone.

The update to the labeling came after the FDA received more than 150 reports of serious adverse events from taking fluoroquinolones. For many patients, the severe side effects left them disabled and unable to work, resulting in “lack of health insurance, large medical bills, financial problems, and family tension or dissolution.”

The side effect most often reported by patients is chronic pain, including muscle pain and joint pain, but patients also reported experiencing tendonitis, tendon rupture, numbness, muscle weakness, joint swelling, anxiety, and depression, among others.

The first label update for fluoroquinolones came in July 2008 to include the increased risk of tendinitis and tendon rupture. In August 2013 the FDA revised the label again to include the risk for irreversible peripheral neuropathy or severe nerve damage.

This latest labeling update comes after a safety communication released by the FDA this past May advising fluoroquinolones only be used in the most serious bacterial infections.