Linezolid and Thrombocytopenia: is the FAERS signal real?
Linezolid ↔ Thrombocytopenia
Linezolid, an oxazolidinone antibiotic for resistant Gram-positive infections, causes reversible myelosuppression — most often thrombocytopenia, but also anaemia and, less commonly, leukopenia. Risk is clearly duration-dependent: it rises sharply after about two weeks of therapy, which is why the label recommends weekly blood counts and cautious use beyond 14–28 days. The mechanism is a time-dependent suppression of bone-marrow precursor proliferation, distinct from the immune-mediated cytopenias of some other drugs. Because it is dose- and duration-related and recovers off-drug, it behaves more like a predictable toxic effect than an idiosyncratic one, making it one of the cleanest antibiotic haematologic signals. The large count reflects both the true effect and the drug's role as a last-line MRSA agent.
Regulatory basis: linezolid prescribing information (myelosuppression warning; weekly blood-count monitoring). Randomized comparative antibiotic trials (linezolid vs tedizolid).
| Bradford Hill viewpoint | Status | Note |
|---|---|---|
| Temporality (necessary) | met | Platelet count falls during therapy and recovers after it stops |
| Strength | met | PRR 14 on a moderate co-report count |
| Consistency | met | Reproduced across randomized trials and cohorts |
| Specificity | partial | Shared with other myelosuppressive and infectious causes of low platelets |
| Biological gradient | met | Sharply duration-dependent — the basis for the weekly-count guidance |
| Plausibility | met | Reversible suppression of bone-marrow precursors is well described |
| Coherence | met | Coheres with the label's monitoring requirement |
| Experiment | met | Randomized head-to-head trials with platelet endpoints confirm the signal |
| Analogy | met | Analogous to chloramphenicol-associated myelosuppression |
This page's own qualitative read, not an automated/citation-gated assessment.
✓ Trial evidence found — linezolid vs tedizolid for hospital-acquired pneumonia (NCT02019420), N=718
| Term (as recorded) | Linezolid (n=361) | Tedizolid (n=357) |
|---|---|---|
| Thrombocytopenia (serious) | 5 | 0 |
Serious thrombocytopenia appears on the linezolid arm and not on the comparator — direct randomized evidence that even within a short treatment course, linezolid suppresses platelets more than a related newer agent. The duration-dependent escalation seen in practice is captured only partly by trials of this length. View on ClinicalTrials.gov →