Psychiatric Drug Interactions with Myasthenia Gravis

Absolutely Contraindicated Psychiatric Medications

Benzodiazepines should be avoided in all myasthenia gravis patients except those who are imminently dying, due to severe risk of respiratory compromise 1
The American College of Oncology recommends that benzodiazepines, including lorazepam and midazolam, carry warnings specifically for myasthenia gravis 1
The respiratory depressant effects of benzodiazepines are particularly dangerous given the underlying neuromuscular weakness affecting respiratory muscles 2

The American College of Oncology recommends that first-generation antipsychotics, such as haloperidol, can be used but requires careful monitoring for extrapyramidal symptoms, orthostatic hypotension, and QTc prolongation 1
The American College of Oncology recommends starting haloperidol at 0.5-1 mg orally or subcutaneously, with a maximum of 5 mg/24 hours 1
The American College of Oncology warns that combining olanzapine with benzodiazepines has resulted in fatalities due to oversedation and respiratory depression 1

The American College of Clinical Oncology recommends measuring negative inspiratory force (NIF) and vital capacity (VC) to establish respiratory baseline 5, 2
The American College of Clinical Oncology applies the "20/30/40 rule": vital capacity <20 ml/kg, maximum inspiratory pressure <30 cmH₂O, or maximum expiratory pressure <40 cmH₂O indicates high risk 5, 2
The American College of Clinical Oncology recommends performing complete neurological examination focusing on ptosis, diplopia, dysphagia, and generalized weakness 4, 5

The American College of Clinical Oncology recommends permanently discontinuing the offending psychiatric medication 3, 4, 2
The American College of Clinical Oncology recommends admitting patients to ICU for monitoring 3, 4, 2
The American College of Clinical Oncology recommends initiating high-dose corticosteroids: methylprednisolone 2-4 mg/kg/day IV or prednisone 1-1.5 mg/kg/day orally 3, 4, 2
The American College of Clinical Oncology recommends starting IVIG 2 g/kg over 5 days (0.4 g/kg/day) OR plasmapheresis for 5 sessions 3, 4, 2

The American College of Oncology warns against using benzodiazepines for anxiety in myasthenia gravis patients due to severe risk of respiratory compromise 1
The American College of Oncology warns against combining olanzapine with any benzodiazepine due to fatal respiratory depression risk 1
The American College of Clinical Oncology recommends avoiding beta-blockers for performance anxiety or akathisia in myasthenia gravis patients 3, 4, 2