Can linezolid (an antibiotic) cause mood changes?

Linezolid and Mood Changes

Yes, linezolid can cause mood changes due to its activity as a monoamine oxidase inhibitor (MAOI), which can affect serotonin levels and potentially lead to psychiatric symptoms including mood alterations.

Mechanism of Action

Linezolid is an oxazolidinone antibiotic that works by inhibiting bacterial protein synthesis. However, it also has MAOI properties that can affect neurotransmitter levels in the brain:

• Acts as a weak, nonselective, reversible inhibitor of monoamine oxidase 1
• Can increase serotonin levels in the central nervous system
• This MAOI activity is the basis for potential neuropsychiatric effects

Documented Psychiatric Side Effects

The British Thoracic Society guidelines specifically mention several neuropsychiatric effects of linezolid 1:

• Mental health changes including depression and psychosis
• Dizziness
• Peripheral neuropathy
• Serotonin syndrome (in severe cases)

Risk Factors for Mood Changes

Several factors increase the risk of experiencing mood changes with linezolid:

• Concurrent use of serotonergic medications (e.g., SSRIs, SNRIs, TCAs) 2
• Higher doses of linezolid
• Prolonged therapy with linezolid
• Pre-existing psychiatric conditions

Serotonin Syndrome Risk

Linezolid's MAOI activity creates a particular concern for serotonin syndrome when combined with other serotonergic medications:

• The Infectious Diseases Society of America warns about this interaction 1
• Symptoms can include confusion, agitation, anxiety, tremors, and muscle rigidity 2
• In severe cases, can progress to fever, seizures, arrhythmias, and unconsciousness 2
• While a recent study suggests the risk may be lower than previously thought in older adults taking antidepressants 3, caution is still warranted

Contraindications

The British Thoracic Society guidelines specifically contraindicate linezolid in patients with 1:

• Uncontrolled hypertension
• Phaeochromocytoma
• Carcinoid tumor
• Thyrotoxicosis
• Bipolar depression
• Schizophrenia
• Acute confusional states

Monitoring Recommendations

For patients taking linezolid who experience mood changes:

1. Consider discontinuing linezolid if safe alternatives exist
2. Monitor closely for worsening psychiatric symptoms
3. Avoid concurrent use of serotonergic medications when possible
4. Consider reducing the dose if benefits outweigh risks
5. Limit duration of therapy to minimize neuropsychiatric effects

Alternative Antibiotics

If mood changes occur and are intolerable, consider alternative antibiotics based on the infection being treated:

• Vancomycin for MRSA infections
• Daptomycin for gram-positive infections
• Tigecycline for broader coverage
• Quinupristin-dalfopristin for gram-positive infections

Conclusion

Linezolid's MAOI activity can indeed cause mood changes, ranging from mild alterations to severe psychiatric symptoms. Healthcare providers should be vigilant about this potential side effect, especially in patients with pre-existing psychiatric conditions or those taking other serotonergic medications.