John Davis

Written by John Davis


Should a Runner Avoid Fluoroquinolone Antibiotics to Preserve Tendon Health? The Research may Indicate “Yes”

The past two weeks we’ve looked at two types of drugs that are commonly used for treating running injuries: Non-steroidal anti-inflammatories and corticosteroid injections.

While we’re on the topic of prescription medication and running, there is another drug category that deserves deliberation: Fluoroquinolone antibiotics.

This medication category includes drugs with trade names like Cipro, Levaquin, and Avelox, among others.

Fluoroquinolones are immensely useful antibiotics, especially in cases of serious illness, but some recent reports have connected them to the development of serious cases of tendonitis or tendon rupture.

While this appears to be fairly rare, and doesn’t disqualify their use in all cases, it’s something you should be aware of as a runner.

The research on antiobiotics (Fluoroquinolones) and tendon inflammation and rupture

The earliest reports of fluoroquinolones causing tendonitis and tendon ruptures came in the early 1990s, when physicians began publishing case studies. A collection of 42 reports was authored by Paul van der Linden and coworkers at a variety of hospitals in The Netherlands.1

Of the 42 tendonitis reports, 90 percent concerned the Achilles tendon. Most cases did eventually heal, many cases were bilateral (involving both Achilles tendons), and a quarter of the patients had suffered a rupture.

By the beginning of the twenty-first century, enough data had been collected to form the basis for some review studies that evaluate the overall research.

One such review, authored in 2003 by Yasmin Khaliq and George Zhanel in Canada, formed the statistical basis for understanding the tendonitis and rupture in people taking fluoroquinolones phenomena.2

Khaliq and Zhanel showed that half of all cases occurred within eight days of beginning treatment, and factors like kidney failure and corticosteroid use increased the tendon damage risk.

Interestingly, and for unknown reasons, men are affected at a higher rate than women. However, the lack of any type of control group hindered the researchers’ ability to predict the risk for the general population.

Statistical analysis

In 2006, a much larger study by G. Corrao and colleagues at the University of Milan-Bicocca in Italy examined 22,000 cases of fluoroquinolones-induced tendonitis, comparing them to 104,000 control cases.3

The statistical analysis predicted that about one in 6,000 people treated by fluoroquinolones would suffer an Achilles tendon rupture, confirming its relative rarity.

While 1/6000 (0.017 percent) poses only a minute risk for an individual, it was significant enough in the context of an entire population to persuade the FDA in 2008 to put a “black box” warning on the Fluoroquinolone antibiotics label alerting consumers to the potential for developing tendonitits and tendon rupture.4

But unlike the patients in the reviewed reports, most of whom were probably sedentary, runners put considerable stress on the Achilles tendon, but no scientific data has been compiled on how the risks of Fluoroquinolones could be different for an athlete.

It’s not even clear why the Achilles tendon is the type most frequently affected by Fluoroquinolone-related tendonitis —some authors believe it is because of the substantial size or poor blood supply to the area, but others suspect that the intensive pressure it endures during ambulatory activity renders it disproportionately vulnerable compared with other tendons.

If this were the case, it would follow that tendonitis and tendon rupture risk would be higher for runners, but of course this is all speculation as of right now.

Concluding thoughts

At the end of the day, Fluoroquinolones remain a tremendously useful and even life-saving class of medication. The risk of tendonitis or tendon rupture is small but notable.

As with any medical decision, you should work with your doctor to understand the medications you’re given.

When your doctor prescribes any antibiotic to you, mention that you are a runner and ask about possible complications or risks—especially if you are prescribed a Fluoroquinolone.

Obviously, a small risk of tendonitis is an acceptable trade-off in cases of serious illness, so the risk-benefit analysis is more applicable to mundane infections and situations where another antibiotic might be just as effective, without the risks of tendon injury.

In the next few years, there may be more research published on this topic; hopefully some of that will include guidelines for Fluoroquinolones use in athletes. Until then, work with your doctor to make an informed choice.

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1. Van der Linden, P. D.; van Puijenbroek, E.; Feenstra, J.; In 't Veld, B. A.; Sturkenboom, M. C. J. M.; Hernings, R. M. C.; Leufkens, H. G. M.; Stricker, B. H. C., Tendon Disorders Attributed to Fluoroquinolones: A Study on 42 Spontaneous Reports in the Period 1988 to 1998. Arthritis & Rheumatism 2001, 45 (3), 235-239.
2. Khaliq, Y.; Zhanel, G. G., Fluoroquinolone-Associated Tendinopathy: A Critical Review of the Literature. Clinical Infectious Diseases 2003, 36 (11), 1404-1410.
3. Corrao, G.; Zambon, A.; Bertù, L.; Mauri, A.; Paleari, V.; Rossi, C.; Venegoni, M., Evidence of tendinitis provoked by fluoroquinolone treatment: a case-control study. Drug Safety 2006, 29 (10), 889-896.
4. Tanne, J. H., FDA adds "black box" warning lable to fluoroquinolone antibiotics. British Medical Journal 2008, 337 (7662), 135.

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7 Responses on “Should a Runner Avoid Fluoroquinolone Antibiotics to Preserve Tendon Health? The Research may Indicate “Yes”

  1. This is not theoretical – a runner friend of mine has experienced tendon problems while taking Cipro, and he’s quick to warn anyone he knows who is going on antibiotics because of it.

  2. I am pretty sure this is when my achilles went south was after taking this med to treat bronchitis. The doctor told me afterwards that it might effect my achilles but I was in no condition to ask questions when it was administered.

  3. My wife, a runner, took cipro. She is now in a wheelchair. She has neuropathy pain, tmj, tendon pain in several places, she can’t chew solid food, can’t use her hands. She lost everything she loved. It’s been 12 weeks since she took it. Things get worse every day. No studies on how to cure the toxicity from this drug.

    • I am so sorry for your wife. I also took the poison, it affected my ankles, back, wrists, the most damage was done to my knees, it’s been over a year for me. I recently found relief by using a tens 3000 unit that a therapist found on amazon for $30. Supposedly it increases the blood flow to the affected areas. I was also a runner. God bless and good luck.

  4. I am a personal trainer who suffers from systemic tendinopathy after being on Cipro for less than 48 hours. That was 12 weeks ago and I am still developing symptoms. My Achilles tendons are the most concerning, and I have had to cut back on my work load and am considering taking the summer off completely to see if I can heal. Even gentle exertion flares up my tendons. Fluoroquinolones should be last resort antibiotics. I strongly suggest you avoid them unless there are no other options available to you. Here is a link to a study specifically about the use of FQs with athletes.

  5. UCSD Fluoroquinolone Effects Study

    Have you taken an antibiotic such as Cipro (ciprofloxacin), Levaquin (levofloxacin), or Avelox (moxifloxacin)? Would you be willing to help in a survey-based medical research study?

    Dr. Beatrice A. Golomb and her colleagues at the University of California, San Diego are conducting a new study to identify and describe side effects and risk factors for good and bad outcomes involving antibiotics in the fluoroquinolone class. Other example fluoroquinolones include Zymar (gatifloxacin), Floxin (ofloxacin), Zagam (sparfloxacin), Trovan (trovafloxacin), Tavanic, and Vigamox.

    Whether you believe you have experienced side effects or you believe you have tolerated them, you are invited to participate in this voluntary study. Participants possessing English language fluency from all countries are accepted.

    Study participants will be asked to complete questionnaire(s). By participating in these surveys, you can help us further understand the effects of fluoroquinolones and report findings to the medical community (including prescribing physicians) and the general public. Surveys will cover your overall health, well-being, fluoroquinolones taken, and symptoms; impacts on your life and career; and your personal story.

    For those without side effects, there is currently just one survey taking 20-30 minutes to complete.

    For those having adverse effects, there are currently 3 (voluntary) questionnaires that can be done separately, each taking approximately 40-90 minutes (time varies per individual). Each survey addresses a different set of concerns related to fluoroquinolone effects. More voluntary surveys may be available in the future. Compensation for taking the surveys is not available.

    If there is a chance you are interested in participating, please visit our website at:

    for further information on this important study.

    If you know of anyone else who might consider participating, then please pass on our website address. We truly appreciate your participation and referrals.

    -The UCSD Fluoroquinolone Effects Study

  6. Don’t just ask about the risks, insist on an alternative antibiotic. Basically you want to ask for an antibiotic that does not have fluoride in it. The fluoride causes the tendon structure to weaken to where it might rupture with stress. The fluoride ion has nonstick properties (fluoride compounds are the ingredient in Scotchguard and Teflon). Problem is when it gets in your tendons, the tendon strands break apart leading to rupture. Tendons remain weak months after finishing the antibiotic.

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