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Antibiotic Side Effects Rarely Examined, Report Finds


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Patient handing a prescription to a pharmacist

Patients have filed more than 60,000 reports of complications from fluoroquinolone antibiotics. Their reports to the U.S. Food and Drug Administration detail hundreds of thousands of side effects. The reports include more than 6,500 deaths since the 1980s. But research on fluoroquinolones’ side effects rarely happens.

Fluoroquinolones include brand names Cipro, Levaquin and Avelox.

The journal Nature looked at the state of fluoroquinolone research. It found researchers still don’t know why the drugs cause “rare but disabling” side effects. It also found frequent indifference from medical professionals and regulators over reported problems.

Fluoroquinolone Research Faces Resistance

The article identified several reasons for sparse fluoroquinolone side effect research.

It found there is little interest in researching drugs already marketed for decades. Drug makers have no incentive to review profitable products. Some researchers are hesitant to publish studies critical of drug companies. They fear reprisals from big, well-funded corporations.

Antibiotic researchers tend to focus their efforts on antibiotic resistance. Others work on finding new antibiotics. This draws resources away from examining existing drugs.

Fluoroquinolones Pose Devastating Side Effects

The most frequent fluoroquinolone side effects are tendon rupture and permanent nerve damage.

Two studies have also linked fluoroquinolones to serious heart problems. Researchers found the drugs may cause aortic aneurysms. These are bulges in the aorta – the artery that carries blood from the heart. Aortic aneurysms can burst or tear. Doctors call these tears aortic dissections.

A 2015 JAMA study looked at aortic aneurysms and aortic dissections. It found a two-fold risk increase if people took the drugs. A BMJ study that same year found an almost three-fold increase in aneurysm risk. Researchers in the BMJ study looked at medical records for 1.7 million people. They said reducing unnecessary prescriptions would have prevented 200 aneurysms.

How Fluoroquinolones Attack Cells

Evidence suggests fluoroquinolones damage mitochondria. These are parts of human cells that produce energy. Every cell contains mitochondria and any cell may be vulnerable. Attacking mitochondria could also explain why fluoroquinolone side effects worsen and spread.

The Nature article listed 30 years of studies exploring the mitochondria link. But it said this connection “still isn’t widely appreciated” in the medical community.

It also found there is little financial support for fluoroquinolone research. At least one researcher is conducting a study without any funding.

FDA Strengthens Fluoroquinolone Warnings

The FDA added the first “black box” warning to fluoroquinolone labels in 2008. It added two more since then. Black boxes are the FDA’s most serious warnings.

Fluoroquinolone Black Box Warnings:

  • 2008: Tendonitis and tendon rupture
  • 2013: Can worsen myasthenia gravis – a neuromuscular and autoimmune disease
  • 2016: Permanent nerve damage

The FDA has ordered about 20 other fluoroquinolone label updates in the past five years. Nature reported that doctors have responded slowly to the updates. And data shows fluoroquinolones are over-prescribed.

Data-research company IQVIA tracks fluoroquinolone prescriptions. It says one in four fluoroquinolone prescriptions in 2014 were unnecessary. Five percent were for conditions antibiotics do not treat. Another 20 percent were for conditions that call for other drugs first.

Prescriptions have dropped in recent years.

Doctors wrote 32 million fluoroquinolone prescriptions in 2015. Prescriptions declined 10 percent in 2016. They also declined in the first half of 2017.

As prescriptions declined, lawsuits over fluoroquinolone side effects have increased.

People who suffered nerve damage filed more than 1,000 lawsuits in recent years. A federal panel combined more than 770 lawsuits into a federal litigation in 2015. Other people have filed lawsuits claiming fluoroquinolones caused their aortic aneurysms and dissections.

Terry Turner
Written By Terry Turner Writer

Terry Turner has been writing articles and producing news broadcasts for more than 25 years. He covers FDA policy, proton pump inhibitors, and medical devices such as hernia mesh, IVC filters, and hip and knee implants. An Emmy-winning journalist, he has reported on health and medical policy issues before Congress, the FDA and other federal agencies. Some of his qualifications include:

  • American Medical Writers Association (AMWA) and The Alliance of Professional Health Advocates member
  • Centers for Disease Control and Prevention Health Literacy certificates
  • Original works published or cited in Washington Examiner, MedPage Today and The New York Times
  • Appeared as an expert panelist on hernia mesh lawsuits on the BBC
Edited By

5 Cited Research Articles writers follow rigorous sourcing guidelines and cite only trustworthy sources of information, including peer-reviewed journals, court records, academic organizations, highly regarded nonprofit organizations, government reports and interviews with qualified experts. Review our editorial policy to learn more about our process for producing accurate, current and balanced content.

  1. Marchant, J. (2018, March 21). When Antibiotics Turn Toxic. Nature. Retrieved from
  2. U.S. Judicial Panel on Multidistrict Litigation. (2018, March 15). MDL Statistics Report. Retrieved from
  3. U.S. Food and Drug Administration. (2016, July 26). FDA Updates Warnings for Fluoroquinolone Antibiotics. FDA News Release. Retrieved from
  4. Daneman, N. et al. (2015, November 18). Fluoroquinolones and collagen associated severe adverse events: a longitudinal cohort study. BMJ. Retrieved from
  5. Lee, C. et al. (2015, October 5). Risk of Aortic Dissection and Aortic Aneurysm in Patients Taking Oral Fluoroquinolone. JAMA. Retrieved from
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