These antibiotics can cause Achilles tendonitis and tendon rupture
Updated: 5 days ago
Fluoroquinolone antibiotics are highly effective broad‐spectrum antibiotics that work for a wide variety of infections, but they can have a very negative effect on tendons. They can cause both Achilles tendonitis and Achilles tendon rupture in fit and active people. The current medical guidelines are that Fluoroquinolone antibiotics should only be used in cases where all other treatment options have failed.
Other antibiotics like tetracycline, hydrochloride, and azithromycin have also been linked to tendonitis, but they don't appear to be as harmful as fluoroquinolones. Remember, if you need more help with an Achilles injury, you're welcome to consult one of our team via video call.
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Types of fluoroquinolone
All of these types of fluoroquinolones have been shown to affect tendons:
Why do fluoroquinolones cause tendon injury?
In short, fluoroquinolones interfere with the collagen turnover in your tendons. All the cells in our bodies, including the collagen fibres in our tendons, are constantly renewing – old ones are being absorbed and replaced by new healthy ones. These antibiotics seem to prevent the body from forming new collagen fibres.
You may notice that I'm using the word tendonitis in this article rather than tendinopathy, and that's because fluoroquinolones do seem to cause quite a dramatic inflammatory reaction in the tendons with reports of red, hot, and swollen Achilles tendons. There are also reports of sudden rupture without any preceding symptoms.
It’s been shown to also affect cartilage and bones, especially in juvenile weight-bearing joints, and should not be used in children.
What is a safe dose?
The research has shown that, where tendons are concerned, there’s no such thing as a “safe” dose of fluoroquinolones. For some patients, tendon pain has started as soon as two hours after the first dose, while other patients were affected as long as six months after they had stopped taking the medication.
Anyone using or who have used fluoroquinolones in the last six months are at risk of Achilles tendonitis and/or Achilles tendon rupture, but there are some factors that can increase your chances of developing these injuries.
Tendon loading sports: When we do tendon loading sports (like running and jumping), our Achilles tendons develop micro-damage. This is normal. After every exercise session, the body repairs this micro-damage, and as a result your tendon becomes stronger.
Unfortunately, fluoroquinolones interfere with this process and stop your tendon from forming new collagen fibres to repair the damage. You’re at a high risk of developing Achilles tendinitis/tendinopathy or tearing your Achilles tendon if you do tendon loading sports within six months of using fluoroquinolone antibiotics.
Corticosteroid use: We know from the research that long term use of corticosteroid drugs (tablets) can predispose patients to tendon injury. In one study, patients who were prescribed both fluoroquinolones and corticosteroids had a 46-fold greater risk of Achilles tendon rupture than those taking neither medication.
Age: As we get older, our tendons take longer to recover and produce new cells, so it is no surprise that older people are more likely to develop Achilles tendon injuries when prescribed fluoroquinolones.
Diabetes mellitus, rheumatic disease, gout, and hyperparathyroidism are all conditions that have been shown to be risk factors for developing Achilles tendinopathy, and they seem to further increase your risk of developing Achilles injuries when you use fluoroquinolones.
What if I have to take these antibiotics?
If you do have to take these antibiotics, I would advise that you keep your running volume and other tendon loading activities (jumping and walking) down and rather add in activities like swimming and cycling. But it may be wise to leave out exercise altogether until you've stopped taking the medication and then ease into low load activities first.
You may also benefit from taking supplements that can help with tendon health. Your doctor should be able to advise on what the best strategy is for you.
How we can help
Need more help with your Achilles injury? You’re welcome to consult one of the team at TMA online via video call for an assessment of your injury and a tailored treatment plan.
We're all UK Chartered Physiotherapists with Master’s Degrees related to Sports & Exercise Medicine. But at Treat My Achilles we don't just value qualifications; all of us also have a wealth of experience working with athletes across a broad variety of sports, ranging from recreationally active people to professional athletes. You can meet the team here.
About the Author
Maryke Louw is a chartered physiotherapist with more than 15 years' experience and a Master's Degree in Sports Injury Management. Follow her on LinkedIn and ResearchGate.
Khaliq Y, Zhanel GG. Fluoroquinolone-Associated Tendinopathy: A Critical Review of the Literature. Clinical Infectious Diseases 2003;36(11):1404-10. doi: 10.1086/375078
Lang TR, Cook J, Rio E, et al. What tendon pathology is seen on imaging in people who have taken fluoroquinolones? A systematic review. Fundamental & Clinical Pharmacology 2017;31(1):4-16. doi: 10.1111/fcp.12228
Lewis T, Cook J. Fluoroquinolones and Tendinopathy: A Guide for Athletes and Sports Clinicians and a Systematic Review of the Literature. Journal of Athletic Training 2014;49(3):422-27. doi: 10.4085/1062-6050-49.2.09
Azithromycin and Tendonitis - a phase IV clinical study of FDA data
Tetracycline hydrochloride and Tendonitis - a phase IV clinical study of FDA data