Moxifloxacin wrecked more than my tendons — now even pizza can cost me a week

How it started

I was 24 when a course of Moxifloxacin 400mg 5pills in 2022 changed how my body works. The early damage was obvious: tendons (bilateral Achilles tendinopathy), cervical instability, crushing fatigue — what the literature calls Fluoroquinolone-Associated Disability (FQAD), with mitochondrial dysfunction later confirmed on complexes I and IV. The gut piece is the one I understood last. It didn't arrive as an event. It arrived as a slow narrowing of what I could eat.

A few years ago I could eat a pizza. Now three or four slices at a friend's birthday cost me a week — not dramatic pain, just a transit that goes sideways and stays there. [Choose what's true for you: "Loose, incomplete stools" / "Slow, laborious transit with pain on defecation" / "Alternating — mostly slow and incomplete, with loose episodes".] The constant feeling that something is still stuck near the exit. Bloating that fires hardest when I lie down: I nap, wake up, and everything that accumulated while I was horizontal hits at once. Early fullness after small amounts, nausea, reflux, cramps, flatulence, food intolerances, joint pain, and post-meal energy crashes about four hours in. BMI 19.6 (67 kg / 1.85 m) — no weight to spare.

The mechanism I eventually understood: fluoroquinolones can disrupt the migrating motor complex, the cleaning wave that sweeps the small intestine between meals (they inhibit GABA-A receptors, which regulate vagal output to the gut). When that's impaired, things stagnate, and your margin for a bad meal disappears. It's not that pizza is uniquely violent. It's that I lost the ability to absorb the hit.

I also have ADHD and a tendency to over-optimize, which matters for how I handle supplements: I stack too much, and I know it.

Testing

Comprehensive functional panel, April 2026. The good news first, because it reframed everything: 8-OHdG 3.15 (normal <5.10) — my DNA isn't being oxidized. Liver, kidneys, glucose clean. Zonulin 9.2 — no leaky gut. Candida serology negative. Erythrocyte magnesium and vitamin D optimal.

What was off: homocysteine 11.40 (optimal <8.8). Plasma copper 710 (range 800–1300) — a real deficit, and copper is a cofactor for complex IV, exactly the one fluoroquinolones hit. DHA 5.17% (range 6.90–9.20), omega-3 index 6.18%, AA/EPA ratio 17.40 (target <12.70) — my ALA→DHA conversion is broken, plant omega-3s do nothing for me. SOD 30.5 and GPX 385.73, both overactivated.

The gut signals were subtle but consistent: LBP 17.64 (range 5–15) — low-grade circulating bacterial endotoxin. CoQ10 1384 (range 600–1100), flagged by the lab as possible dysbiosis. Indican 13.81 and p-cresol 12.57, in range but present. The limitation nobody told me: urinary organic acid panels cannot see methane. I had a "normal" microbiome workup that simply couldn't detect what I was looking for.

Lactulose breath test, August 2026 (home kit from a French lab, 10 g lactulose, 3 h, 10 samples):

Hydrogen: 11, 11, 11, 12, 9, 8, 9 ppm from T0 to T90 — flat — then 53 / 92 / 120 ppm at T120 / T150 / T180. Methane: 5, 6, 5, 6, 5, 5, 6 ppm through T90, then 13 / 17 / 18 ppm at T120 / T150 / T180. Against the North American Consensus (Rezaie 2017): negative for hydrogen SIBO (no rise ≥20 ppm before 90 min; the late rise is the lactulose reaching the colon), positive for IMO at low grade (CH4 ≥10 ppm, max 18, baseline 5). I felt clear gas movement at T+26 minutes while the curve was still flat — which points to an osmotic / visceral-hypersensitivity component, not small-bowel fermentation. The lab refused to interpret because I declared I'd skipped the pre-test mouthwash. The raw values came in a technical annex with a note that the samples themselves were valid. The curve has no early hydrogen artifact, which is the only thing the mouthwash prevents.

Not done yet, both on my list: colonic transit time and anorectal manometry — because I suspect the motor side is as much the problem as the methane.

Treatments, and what actually happened

Core mitochondrial protocol (not gut treatments, listed for context and interactions): NMN, TMG, MitoQ, PQQ, R-lipoic acid, active B12/B9/B6, EPA/DHA at therapeutic dose (1260 EPA + 900 DHA), collagen peptides with vitamin C, glycine, copper bisglycinate, silicium.

Two lessons worth more than the supplements themselves:

I took copper and quercetin together for two months. Copper is redox-active and quercetin can flip pro-oxidant in its presence (Fenton chemistry). I was working against myself. Separating them (copper at lunch, zinc/quercetin at night) was free and I should have caught it earlier. More is not better. My homocysteine was partly driven by my own NMN dose — nicotinamide has to be methylated to clear, which burns SAM — and I was adding TMG to compensate. A supplement to fix another supplement's side effect is a warning sign, not a solution.

Gut-specific:

Intermittent fasting (last meal ~22:00, first ~12:30) and a 10–15 minute walk after meals: helped. More for my transit than anything I've swallowed. Ginger extract as a prokinetic: partial help, well tolerated. Keeping it. Bilastine (H1 antihistamine): clear positive therapeutic response. Points to a mast-cell / histamine component and reframed a lot — pizza isn't just FODMAPs for me: aged cheese, concentrated tomato, fermented dough, cured meat. A histamine load on a reactive terrain. Fermented "gut health" foods are not an option. Berberine (short trial): seemed to blunt the post-meal crashes (glycemic/AMPK effect), but I stopped — it inhibits mitochondrial complex I, the last thing my physiology needs. Not using it as an antimicrobial. MCT oil for post-meal crashes: partial help on energy, neutral on gut. Resveratrol: identified as a co-culprit in the 4-hour crashes; removed. NAC: stopped on specialist advice (redundant with liposomal glutathione and glycine, questionable on a mast-cell terrain). Magnesium: helps transit somewhat (switching to citrate during treatment). low-FODMAP

Practitioners

This is the hardest part to write. Most doctors either don't know what fluoroquinolone toxicity is, or reflexively prescribe more antibiotics without reading the file. The ones who take it seriously often can't help. The breath test was self-ordered because no one would prescribe it. I manage my own labs, dosing and sequencing — exhausting and, honestly, not safe. Doing this alone means nobody tells you when you're going too far.

The best input came from a physician who works specifically with FQ-injured patients, and it was subtractive: cycle the NMN, stop the NAC, test for MCAS before deciding anything else. The most valuable advice I've received has consistently been about removing things.

The low point

Getting the breath test back marked "not interpretable," reading it myself — and then discovering that the flagship "stabilized allicin" product the entire methane community recommends contains about 54 micrograms of allicin per 180 mg capsule (the rest is maltodextrin). A fresh garlic clove has 5–10 mg. The protocols built on "450 mg allicin" were built on a powder weight. And the studies showing herbs matching rifaximin (Chedid 2014) didn't contain any garlic at all — they used thyme/oregano oils and berberine formulas. A lot of the standard natural protocol rests on marketing and repetition rather than dose and data.

Where things stand now (August 2026)

About to run one measured 4-week cycle, deliberately simple, chosen to avoid anything with a mitochondrial or tendon signal:

Enteric-coated oregano oil standardized in carvacrol, titrated up, taken with light meals (the 10% "made worse" for oregano in this database is exactly why I'm going slowly) Real garlic: a crushed fresh clove with meals, or standardized garlic powder (10–20 mg allicin potential/day) — not "stabilized allicin" capsules Ginger at bedtime on an empty stomach as the prokinetic, continued 8–12 weeks past the antimicrobials Meals spaced 4–5 h, overnight fast kept, no strict low-FODMAP, no fermented foods Activated charcoal only on die-off days, 2 h away from everything else

Then a repeat breath test 2–4 weeks after the cycle. If methane drops under 10 ppm and transit holds, the gas was driving. If it rebounds fast despite the prokinetic, I stop cycling antimicrobials and go the medical route: transit study, manometry for possible dyssynergia, prucalopride, macrogol — treating the motor, not the passengers.

My oxidative markers say the core damage is under control. What's left is real, but it's a smaller problem than what I started with.

If you're early in this: get the breath test with lactulose, not glucose (glucose only reads the proximal small bowel), make sure methane is measured, read the composition line on every supplement rather than the number in bold, and find one person who will look at your whole file even if they're not an expert in your specific injury. Managing this alone is the part that breaks you, not the illness.