Antibiotics and Achilles Tendon Rupture: The Fluoroquinolone Warning

You finished a week of antibiotics for a chest or bladder infection and finally feel like yourself again. Then the back of your heel starts to ache on your morning walk. A few days later it is swollen and stiff, and you are not sure why. You did not do anything new.

If that antibiotic was ciprofloxacin (Cipro), levofloxacin or a related drug, that heel pain matters. These medicines can affect tendons, and the Achilles tendon is the one most often involved.

What are fluoroquinolones?

Fluoroquinolones are a group of strong antibiotics. In Canada they include ciprofloxacin, levofloxacin, moxifloxacin, norfloxacin and ofloxacin. They are useful for some serious infections, and many people take them without any problem.

But they carry a known tendon warning. A 2013 systematic review in Drug Safety found that tendon injury with these drugs appears to be rare, but the risk of Achilles tendon rupture was higher in people taking them, especially in the first month after the medicine was started. In 2017, Health Canada reviewed reports of side effects that lasted long after people stopped these drugs. It concluded that tendon problems, along with some nerve and brain side effects, are rare but serious and may be long lasting or disabling, and it asked for the safety information on all of these products to be updated.

Who is most at risk?

The UK medicines regulator (MHRA) lists these groups as higher risk for tendon problems on fluoroquinolones:

• People over 60
• People taking corticosteroids such as prednisone at the same time
• People with kidney problems
• People who have had an organ transplant

The 2013 review also found that taking steroid pills at the same time raised the risk in several studies. If you fit more than one of these groups, it is worth being extra careful with your tendons while you are on the antibiotic and for a while after.

Warning signs to know

Tendon trouble can start within 48 hours of the first dose. It can also show up several months after you finish the medicine, according to the MHRA. Watch for:

• New pain, tenderness or swelling at the back of the heel or lower calf
• Stiffness in the Achilles that is worse first thing in the morning
• Pain in both heels, or in another tendon
• A sudden snap or a feeling like someone kicked you in the back of the calf
• Trouble pushing off, walking normally or rising up onto your toes

When to call 911 or go to the emergency department

Go to the emergency department if you feel a sudden snap, pop or kick at the back of your ankle, especially if you then cannot push off or walk normally. These are signs that the Achilles may have torn. A full tear needs prompt medical care, often in a special boot, so do not wait to see if it settles.

When to call your doctor or pharmacist

Call your doctor or pharmacist the same day if you are taking, or recently took, a fluoroquinolone and you notice any new tendon pain or swelling. The MHRA advises patients to contact their doctor right away at the first sign of tendon pain. Your doctor or pharmacist will tell you whether to keep taking the medicine or switch to something else. Do not make that call on your own.

Until you have spoken to them, rest the sore leg. Skip running, jumping, hill walking and calf raises.

If you are offered one of these antibiotics in the future, tell your prescriber if you have had tendon problems before, if you are over 60, or if you take steroid pills.

Why your physiotherapist asks about antibiotics

When you come to Vaughan Physiotherapy Clinic with heel or calf pain, your physiotherapist will ask about recent medicines, including antibiotics. It can feel like an odd question for a sore heel, but it changes what we do.

• We check the tendon for swelling, tenderness and gaps, and test whether your calf can still lift your heel
• If you recently took a fluoroquinolone, we hold off on heavy tendon loading and tell you to speak with your doctor or pharmacist
• If anything suggests a tear, we stop and send you for urgent medical assessment the same day
• We share what we find with your family doctor so your care is coordinated

What physiotherapy can and can't do

Physiotherapy cannot undo a drug reaction, and it does not replace medical advice about your antibiotic. What it can do is help the tendon recover safely once your doctor has a plan.

• Calm things down first: early on, we keep loading gentle and focus on comfortable walking
• Rebuild slowly: tendons need gradual, steady loading to get stronger, and we build up step by step instead of rushing back to sport
• After a rupture: whether you are treated in a boot or with surgery, physio guides the rehab that follows your surgeon's or doctor's protocol

Key takeaways

• Fluoroquinolones such as ciprofloxacin and levofloxacin can cause tendon problems, most often in the Achilles.
• Risk is higher over age 60, with steroid pills, kidney problems or an organ transplant.
• Symptoms can start within 48 hours or months after you finish the medicine.
• New tendon pain on these antibiotics means calling your doctor or pharmacist the same day.
• A sudden snap or kick at the back of the ankle needs the emergency department.

Related reading: You may also find our guides to calf strain and Achilles pain in basketball helpful.

If your heel pain started after a course of antibiotics, or you are recovering from an Achilles injury, our team can assess it carefully and work alongside your doctor. You can learn more about how we treat Achilles tendinopathy.

Call: 905-669-1221

Visit: 398 Steeles Ave W #201, Thornhill, ON

Book online: vaughanphysiotherapy.com

Sources

Cambridge University Hospitals NHS Foundation Trust. (2025). Achilles tendon rupture [Patient information leaflet]. https://www.cuh.nhs.uk/patient-information/achilles-tendon-rupture/

Health Canada. (2017). Summary safety review: Fluoroquinolones: Assessing the potential risk of persistent and disabling side effects. https://www.canada.ca/en/health-canada/services/drugs-health-products/medeffect-canada/safety-reviews/summary-safety-review-fluoroquinolones-assessing-potential-risk-persistent-disabling-effects.html

Medicines and Healthcare products Regulatory Agency. (2019). Fluoroquinolone antibiotics: New restrictions and precautions for use due to very rare reports of disabling and potentially long-lasting or irreversible side effects. Drug Safety Update, 12(8). https://www.gov.uk/drug-safety-update/fluoroquinolone-antibiotics-new-restrictions-and-precautions-for-use-due-to-very-rare-reports-of-disabling-and-potentially-long-lasting-or-irreversible-side-effects

Stephenson, A. L., Wu, W., Cortes, D., & Rochon, P. A. (2013). Tendon injury and fluoroquinolone use: A systematic review. Drug Safety, 36(9), 709 to 721. https://doi.org/10.1007/s40264-013-0089-8

This article is for general information and isn't medical advice. If you have any of the warning signs above, call 911 or contact your doctor right away.