Ciprofloxacin vs Doxycycline: side effects in FDA adverse event reports
At a glance
| Ciprofloxacin | Doxycycline | |
|---|---|---|
| Drug class | – | Tetracycline-class Drug |
| Brand names | – | – |
| FAERS reports | 96,695 | 67,795 |
| Serious | 83% | 72% |
| Death outcome | 9,728 | 6,693 |
| Boxed warning | Yes SERIOUS ADVERSE REACTIONS INCLUDING TENDINITIS, TENDON RUPTURE, PERIPHERAL NEUROPATHY, CENTRAL NERVOUS SYSTEM EFFECTS AND EXACERBATION OF MYASTHENIA GRAVIS • Fl | No |
Signals both drugs share
| Reaction | Ciprofloxacin | Doxycycline | Label screen (A / B) |
|---|---|---|---|
| Nephrogenic anaemia | 755 · PRR 41.7 | 405 · PRR 29.3 | Not in label — unassessed / Not in label — unassessed |
| Rebound acid hypersecretion | 437 · PRR 35.9 | 263 · PRR 28.9 | Not in label — unassessed / Not in label — unassessed |
| Hyperparathyroidism secondary | 415 · PRR 42.4 | 224 · PRR 29.9 | Not in label — unassessed / Not in label — unassessed |
| Chronic kidney disease-mineral and bone disorder | 192 · PRR 47.0 | 120 · PRR 38.7 | Not in label — unassessed / Not in label — unassessed |
Labeled signals distinctive to Ciprofloxacin
- Chronic kidney disease — n=4,554, PRR 13.6 Labeled (related wording)
- Tendonitis — n=2,268, PRR 36.9 Labeled — boxed warning
- Tendon pain — n=2,035, PRR 79.7 Labeled (related wording)
- Tendon rupture — n=1,303, PRR 25.4 Labeled — boxed warning
- Tendon disorder — n=1,135, PRR 45.5 Labeled adverse reaction
- Clostridium difficile colitis — n=586, PRR 12.6 Labeled (related wording)
- Tendon injury — n=341, PRR 21.7 Labeled (related wording)
- Tendon discomfort — n=253, PRR 109.5 Labeled (related wording)
Labeled signals distinctive to Doxycycline
- Sleep disorder due to general medical condition, insomnia type — n=892, PRR 49.6 Labeled (related wording)
- Autoimmune disorder — n=890, PRR 31.6 Labeled (related wording)
Common questions
Which has more reported side effects, Ciprofloxacin or Doxycycline?
Ciprofloxacin has 96,695 FAERS reports and Doxycycline 67,795. More reports does not mean more dangerous: volume follows how widely and how long a drug has been used, prescription vs over-the-counter status, and publicity. The seriousness share (83% vs 72%) is a better like-for-like signal of the kind of problems reported.
Which side effects do Ciprofloxacin and Doxycycline share?
Both drugs carry disproportionality signals for nephrogenic anaemia, rebound acid hypersecretion, hyperparathyroidism secondary, chronic kidney disease-mineral and bone disorder. Shared signals often reflect a shared drug class or the condition both are used for.
Is Ciprofloxacin or Doxycycline safer?
FAERS cannot answer that: it has no denominator and no comparator. Use this page to see which risks are already on each label and which signals are unlabeled, then check the prescribing information and your clinician for your situation.
Sources: openFDA FAERS pair statistics (OpenPV build 2026-09-14), FDA labels via openFDA, openFDA count queries for seriousness and deaths. Pair chosen because it is a commonly searched comparison. Generated 2026-10-08.