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.
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.
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.
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.