What are the common adverse side effects of linezolid?

Common Adverse Side Effects of Linezolid

Linezolid commonly causes gastrointestinal effects, hematologic toxicity, and neurological complications, with the most serious adverse effects typically occurring with prolonged use beyond 2 weeks. 1, 2

Common Adverse Effects

• Gastrointestinal effects: Diarrhea (8.3%), nausea (6.2%), vomiting (3.7%), and constipation (2.2%) are the most frequently reported adverse effects 2
• Neurological effects: Headache (6.5%) and dizziness (2.0%) are common neurological side effects 2
• Infections: Candidiasis, particularly oral and vaginal (1%) 1
• Hepatic effects: Transient increases in liver function tests 1
• Insomnia: Occurs in approximately 2.5% of patients 2
• Rash: Develops in about 2.0% of patients 2

Serious Adverse Effects

Hematologic Toxicity

• Myelosuppression: Includes thrombocytopenia, anemia, and neutropenia 1, 3
• Monitoring recommendation: Weekly complete blood count monitoring for patients receiving linezolid for longer than 2 weeks 2
• Risk factors: Higher doses (>600 mg/day), prolonged treatment courses, pre-existing myelosuppression, and concomitant medications that cause bone marrow suppression 2, 3

Neurological Complications

• Peripheral neuropathy: May be irreversible or only partially reversible, typically occurs after 12-20 weeks of treatment 1, 3
• Optic neuropathy: Increased risk with prolonged treatment, can progress to vision loss 1, 4
• Visual changes: Patients should be monitored for changes in visual acuity, color vision, blurred vision, or visual field defects 2
• Serotonin syndrome: Risk when co-administered with serotonergic agents 2, 3

Metabolic Complications

• Lactic acidosis: Can occur with long-term use 1, 3
• Symptoms: Recurrent nausea, vomiting, unexplained acidosis, or low bicarbonate levels 2

Special Considerations

Drug Interactions

• Monoamine oxidase inhibitors: Avoid concomitant use with other drugs that inhibit monoamine oxidases A or B 1
• Serotonergic agents: Risk of serotonin syndrome when co-administered with SSRIs or other serotonergic medications 2
• Tyramine-rich foods: Large quantities should be avoided due to potential hypertensive reactions 2

High-Risk Populations

• Children: May be particularly susceptible to myelosuppression at the recommended dose of 10 mg/kg twice daily 3
• Patients with renal impairment: May have accumulation of metabolites 1
• Patients with liver disease: Should be monitored closely for adverse effects 1
• Patients with pre-existing conditions: Those with uncontrolled hypertension, pheochromocytoma, carcinoid tumor, thyrotoxicosis, bipolar depression, schizophrenia, or acute confusional states require careful monitoring 1, 3

Monitoring Recommendations

• Complete blood counts: Monitor weekly for the first 2 months, consider reducing to monthly if stable thereafter 1, 2
• Visual function: Regular assessment for patients on extended therapy (≥3 months) and for all patients reporting new visual symptoms 2
• Clinical symptoms: Monitor for signs of peripheral neuropathy, lactic acidosis, and serotonin syndrome 3, 2

Clostridium difficile-Associated Diarrhea

• Linezolid, like other antibiotics, can cause Clostridium difficile-associated diarrhea ranging from mild diarrhea to fatal colitis 2
• Symptoms may appear up to two months after antibiotic use 2

Remember that the risk of serious adverse effects increases with prolonged treatment duration beyond the FDA-approved 28 days 2, 1.