06/13/2026
For decades, fluoroquinolone antibiotic injured patients have reported tendon pain, weakness, tearing, ruptures, instability, and a frightening sense that their connective tissue no longer has the same strength or support. This new unedited* study: "Effects of fluoroquinolone antibiotics on extracellular matrix-related phenotypes in tendon cells", adds another important piece to that puzzle.
Rather than looking only at tendon pain or rupture risk, the researchers examined what fluoroquinolone antibiotics may be doing inside tendon cells and to the extracellular matrix, or ECM. The ECM is the body’s structural support system around cells. In tendons, this matters enormously because tendon strength depends on a highly organized collagen matrix. When that matrix is disrupted, the issue may not simply be “less collagen,” but weaker, poorly assembled connective tissue.
The authors focused mainly on ciprofloxacin and levofloxacin using adult mouse Achilles tendon cells. Their central finding was that fluoroquinolones did more than reduce collagen production. They also disrupted several key parts of tendon matrix health, including collagen assembly and quality, collagen fibril stiffness, fibronectin, lysyl oxidase activity, and active β1-integrin, an important receptor that helps cells attach to and communicate with the surrounding matrix.
This suggests that fluoroquinolones may weaken tendon structure by disturbing both:
➥ ➥ the “building materials” and the “assembly system.”
What they found --
🟡 Ciprofloxacin enters tendon cells through a carrier-mediated process. That means it is not just passively floating around outside the cells; tendon cells appear able to take it up through transport systems. The authors say this was shown in tendon cells for the first time, although they also admit the transporter they identified does not explain all uptake.
🟡 Reduced type I collagen (the major tendon collagen) ➨Levofloxacin and ciprofloxacin reduced type I collagen mRNA and protein, with ciprofloxacin appearing stronger in this model.
🟡 Reduced fibronectin (fibronectin helps organize collagen matrix and supports cell adhesion).
🟡 Increased type V collagen ➨type V collagen helps regulate collagen fibril diameter. The authors suggest that a shift in the type V/type I collagen balance could contribute to thinner or altered collagen fibrils.
🟡 Collagen assembly was strongly inhibited. The collagen network was much more affected than total hydroxyproline content, suggesting the issue is not only “less collagen,” but poorly organized collagen matrix.
🟡 Reduced hydroxyproline content (a marker of collagen content and collagen-related ECM).
🟡 Reduced lysyl oxidase activity. (Lysyl oxidase (LOX) helps cross-link collagen and elastin and what gives connective tissue strength).
🟡 Ciprofloxacin reduced collagen fibril elastic modulus by about 67% and fibril diameter by about 45% in vitro (cell culture), a concrete “structure/strength” finding.
🟡 Reduced active β1-integrin. This matters because β1-integrin helps cells attach to and sense the ECM. The authors speculate that impaired fibronectin and β1-integrin signaling could contribute to anoikis (form of cell death/dysfunction related to poor cell-matrix attachment).
What is new?
The most useful newer contribution is not that fluoroquinolones damage collagen - that was already known but:
1. Tendon-cell uptake of ciprofloxacin
They specifically show carrier-mediated ciprofloxacin uptake in mouse tendon cells. That gives a plausible reason tendon cells themselves may be directly affected, not only indirectly harmed by inflammation or systemic oxidative stress.
2. Collagen assembly versus collagen amount
Importantly, they show the collagen network/assembly can be severely impaired even when total collagen marker reduction is more modest. That helps explain why tissue could be functionally weak even if a simple collagen quantity marker does not look catastrophic.
3. LOX and fibril stiffness
The LOX/collagen fibril stiffness finding is meaningful because it connects FQ exposure to mechanical properties, not just molecular markers, and a 67% reduction in elastic modulus (the collagen structure became less firm and less mechanically strong).
❓The key question…..
How do we help the body rebuild and remodel matrix over time, while avoiding further injury and supporting the cellular systems that create usable collagen?
Evidence from tendon biology and tendinopathy research supports the importance of adequate protein, vitamin C, collagen-building nutrients, mineral cofactors, and progressive tendon loading for connective-tissue remodeling. However, this information comes largely from the general tendon-repair literature, not from studies specifically designed around fluoroquinolone-injured patients. Individuals with FQAD (fluoroquinolone associated disability) may not respond in the same way as the general population, and some may be unable to tolerate standard rehabilitation, treatments or supplement approaches, especially during periods of acute or systemic dysfunction. This is why this new tendon-cell paper is important as its findings point to a broader problem than just collagen.
This unedited study suggests fluoroquinolones may impair collagen production, collagen assembly, LOX activity, fibril strength, collagen balance, fibronectin, and β1-integrin/cell-matrix signaling. Therefore, a rational recovery framework may need to look beyond simply taking collagen and instead consider the larger matrix-repair environment. According to studies, potential support areas may include adequate protein, collagen peptides or collagen-rich foods to provide collagen-building amino acids, vitamin C sufficiency, copper/zinc balance for LOX-related cross-linking, correction of nutritional deficiencies, oxidative-stress and mitochondrial support, careful progressive mechanical loading, and avoidance of overload while the matrix is structurally vulnerable. Dedicated human studies in fluoroquinolone-injured patients are urgently needed to better understand these mechanisms and identify meaningful paths toward recovery.
Currently, much of the feedback regarding what helps or can worsen adverse effects such as tendon issues, still comes from patient experiences within the fluoroquinolone-injured community, with varying outcomes remaining very individual. Several additional clinician-supervised or experimental areas sometimes discussed in tendon repair include shockwave therapy, PRP, hyaluronic-acid/proteoglycan support, and regenerative peptides such as BPC-157 or thymosin β4/TB-500 (not currently FDA approved). Please always do your research and consult with a physician in functional medicine or similar before embarking on any treatments, keeping in perspective that many of those living with fluoroquinolone adverse effects can be living with fragile systems which many doctors are completely unaware of.
Should there be any changes to the early-access journal article once published, this post will be updated.
*✏️Article link:
Anand A, Sakai K, Dickens D, et al. Effects of fluoroquinolone antibiotics on extracellular matrix-related phenotypes in tendon cells. Scientific Reports. 2026. https://doi.org/10.1038/s41598-026-55720-5 [Important Note: This is an unedited early-access version that may undergo further editing before final publication – see the download button for full article]
✏️✏️Even though this journal study in the post link is not in its possible final version, it could be a good paper to print and take with you to tendon related appointments
⚠️⚠️Disclaimer: This article is for educational and informational purposes only. It is not medical advice, does not provide a diagnosis or treatment plan, and should not be used as a substitute for care from a qualified healthcare professional. Fluoroquinolone-associated injury can involve complex, individualized risks. Some interventions, including supplements, exercise, physical therapy, medications, treatments and dietary changes, may be inappropriate or harmful for certain individuals based on many factors. Patients should consult their own healthcare professionals before making changes or starting new protocols.
⚠️⚠️Note: products such as collagen, bone broth and gelatin are animal derived and source quality can vary.
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References
1. Anand A, Sakai K, Dickens D, Tsuzuki S, Minamiguchi S, Asai N, Kazaili A, Akhtar R, Pirmohamed M, Sakai T. Effects of fluoroquinolone antibiotics on extracellular matrix-related phenotypes in tendon cells. Scientific Reports. 2026.
https://www.nature.com/articles/s41598-026-55720-5
2. Buchalski A, et al. Collagen Supplementation on Tendon-Related Structural, Functional, and Clinical Outcomes: A Systematic Review. Journal of Functional Morphology and Kinesiology. 2026;11(1):130.
https://www.mdpi.com/2411-5142/11/1/130
3. Hijlkema A, Roozenboom C, Mensink M, Zwerver J. The impact of nutrition on tendon health and tendinopathy: a systematic review. Journal of the International Society of Sports Nutrition. 2022;19(1):474-504.
https://pmc.ncbi.nlm.nih.gov/articles/PMC9354648/
4. Kjaer M, Langberg H, Heinemeier K, et al. From mechanical loading to collagen synthesis, structural changes and function in human tendon. Scandinavian Journal of Medicine & Science in Sports. 2009;19(4):500-510.
https://paulogentil.com/pdf/From%20mechanical%20loading%20to%20collagen%20synthesis%2C%20structural%20changes.pdf
5. Mousavizadeh R, Hojabrpour P, Eltit F, et al. β1 integrin, ILK and mTOR regulate collagen synthesis in mechanically loaded tendon cells. Scientific Reports. 2020;10:12644.
https://www.nature.com/articles/s41598-020-69267-6
6. Ellingson AJ, Pancheri NM, Eberman LE, Kines KJ, Recker AJ, Bates NA. Regulators of collagen crosslinking in developing and adult tendon. Journal of Orthopaedic Research. 2022;40(8):1821-1834.
https://pmc.ncbi.nlm.nih.gov/articles/PMC9583849/
7. Nguyen PK, Briquez PS, Kyoung J, et al. Tendon mechanical properties are enhanced via recombinant lysyl oxidase treatment. Scientific Reports. 2022;12:13624.
https://pmc.ncbi.nlm.nih.gov/articles/PMC9389157/
