Linezolid is a synthetic antibiotic belonging to the oxazolidinone class of antibacterial agents. It is used to treat infections caused by specific Gram-positive bacteria. As a clinically important antibiotic, understanding its side effect profile and medication precautions is crucial for patients' safe drug use.

What Are the Side Effects of Linezolid?

Common Side Effects

Gastrointestinal reactions: Diarrhea (incidence rate: 8.3%), nausea (6.2%), vomiting (3.7%), and constipation (2.2%).

Neurological reactions: Headache (6.5%), dizziness (2.0%).

Skin reactions: Rash (2.0%).

Other reactions: Insomnia (2.5%), fever (1.6%).

Severe Side Effects of Linezolid That Require Vigilance

Myelosuppression and Thrombocytopenia

Animal studies have shown that linezolid can cause dose- and time-dependent myelosuppression, manifested as decreased bone marrow cells, impaired hematopoietic function, and reduced levels of circulating red blood cells, white blood cells, and platelets.

Clinical observations have found that thrombocytopenia occurs in some patients.

The following populations are at higher risk:

Patients with increased bleeding risk.

Patients with pre-existing thrombocytopenia.

Patients who need to use drugs that may affect platelet function in combination.

Patients with a treatment course exceeding 2 weeks.

Pseudomembranous Colitis

Similar to other antibiotics, linezolid may cause pseudomembranous colitis, with severity ranging from mild to life-threatening.

The mechanism involves altering the normal intestinal flora of the colon, leading to the overgrowth of Clostridioides difficile.

Clinical management principles include:

Mild cases: Discontinue the drug and monitor.

Moderate to severe cases: Supplement fluids, electrolytes, and proteins, and use antibiotics effective against Clostridioides difficile.

Other Potential Severe Reactions

Lactic acidosis: Although not explicitly mentioned in the package insert, it has been occasionally reported in clinical practice.

Peripheral neuropathy and optic neuropathy: The risk increases with long-term use (exceeding 28 days).

Hypersensitivity reactions: Contraindicated in patients allergic to linezolid or any component in the preparation.

Precautions for Linezolid Use

Medication Use in Special Populations

Elderly patients: No significant changes in pharmacokinetics; no dose adjustment is required.

Patients with renal impairment: The metabolism of the parent drug is not affected, but its metabolites may accumulate. The drug should be used after weighing the pros and cons.

Patients with hepatic impairment: No dose adjustment is required for mild to moderate hepatic impairment; there is no data available for patients with severe hepatic impairment.

Pregnant women: Classified as Pregnancy Category C; should be used only when the potential benefit outweighs the risk.

Lactating women: The drug can pass into rat milk; human data are lacking, so it should be used with caution.

Management of Drug Interactions

Sympathomimetic drugs: When used in combination with pseudoephedrine, phenylpropanolamine, etc., blood pressure should be closely monitored. It is recommended to reduce the initial dose and adjust by titration.

Serotonergic drugs: Including antidepressants, etc. Be alert to the symptoms of serotonin syndrome.

Tyramine-containing foods: Avoid excessive intake of foods with high tyramine content (such as aged cheese, fermented meat products, soy sauce, etc.). The tyramine intake per meal should be < 100 mg.