Yes, thrombocytopenia is a recognized side effect of cefazolin.
Cefazolin can cause thrombocytopenia, as explicitly listed in the FDA drug label under hematologic adverse reactions, and this has been confirmed through multiple case reports and pharmacovigilance data. 1
Evidence from FDA Drug Label
The FDA-approved prescribing information for cefazolin directly lists thrombocytopenia among its hematologic adverse reactions 1. This represents the highest level of regulatory acknowledgment that this side effect has been documented and verified through post-marketing surveillance and clinical experience.
Clinical Significance and Real-World Evidence
The thrombocytopenia associated with cefazolin can range from mild to severe:
Case reports document serious outcomes: A 33-year-old woman developed severe thrombocytopenia with petechiae and large hemoperitoneum after receiving cefazolin prophylaxis, requiring ICU admission and blood product resuscitation. Drug-dependent platelet antibodies to cefazolin were serologically confirmed 2.
Myelosuppressive mechanism: Cefazolin, like other cephalosporins, can cause thrombocytopenia through myelosuppressive effects. This has been documented alongside neutropenia in otherwise healthy patients 3.
Pharmacovigilance data: Large-scale analysis of the FDA Adverse Event Reporting System identified cefazolin among β-lactam antibiotics producing strong signals of disproportionate reporting for blood and lymphatic system disorders, including immune thrombocytopenia 4.
High-Risk Populations
Particular caution is warranted in:
- Patients with underlying hematologic disorders (a case of severe thrombocytopenia occurred in a patient with polycythemia vera during cardiac surgery) 5
- Elderly patients over 65 years, where predictive models have identified baseline platelet count, renal insufficiency, and liver cirrhosis as key risk factors 6
- Patients receiving prolonged cefazolin therapy
Clinical Monitoring Recommendations
When prescribing cefazolin:
- Monitor complete blood counts, particularly in patients receiving prolonged therapy
- Be vigilant for signs of bleeding or petechiae
- Consider cefazolin as a potential cause when thrombocytopenia develops during or shortly after treatment
- Discontinue the drug if drug-induced thrombocytopenia is suspected
Differential Diagnosis Consideration
When evaluating thrombocytopenia in patients receiving cefazolin, remember that antibiotics are listed as potential causes of drug-induced thrombocytopenia in the 4T score assessment (the "other" category) 7. However, drug-related thrombocytopenia is often more severe than heparin-induced thrombocytopenia and is typically complicated by bleeding rather than thrombosis.