Some antibiotics can reduce the effectiveness of neuromuscular transmission in a patient with Myasthenia Gravis (MG) and can exacerbate the symptoms of the disease. The table below provides some information about which antibiotics are contraindicated in MG or are to be used with caution.

Please note that this is not a comprehensive list. Please check with Medicines Information (CGH ext 3030; GRH ext 6108) if any other antibiotics are required.

Last Reviewed: 22/03/19

Amoxicillin No information found to suggest a problem in myasthenia gravis.
Benzylpenicillin No information found to suggest a problem in myasthenia gravis.
Ceftriaxone No information found to suggest a problem in myasthenia gravis.
Ciprofloxacin Fluoroquinolones should be avoided in patients with a history of myasthenia gravis. Neuromuscular blocking activity; may exacerbate muscle weakness. Can also unmask subclinical myasthenia gravis.
Clarithromycin Exacerbation of symptoms of myasthenia gravis has been reported in patients.
Clindamycin Clindamycin has been shown to have neuromuscular blocking properties and may enhance the effect of other drugs with this action.
Co-amoxiclav (clavulanic acid & amoxicillin) No information found to suggest a problem in myasthenia gravis.
Co-trimoxazole Sulphonamides have a depressant effect on neuromuscular junction and may increase weakness.
Daptomycin No information found to suggest a problem in myasthenia gravis. Any muscle weakness more likely to be due to raised creatinine phosphokinase (CPK) concentrations.
Doxycycline Due to a potential for weak neuromuscular blockade, care should be taken in administering tetracyclines to patients with myasthenia gravis.
Erythromycin It has been reported that erythromycin may aggravate muscle weakness of patients with myasthenia gravis.
Flucloxacillin No information found to suggest a problem in myasthenia gravis.
Fluconazole No information found to suggest a problem in myasthenia gravis.
Gentamicin Contraindicated in patients with myasthenia gravis - Inhibits acetylcholine release from presynaptic neuron; also has some postsynaptic curare-like action. Aminoglycosides have been associated with death when used in patients with a history of myasthenia gravis.
Levofloxacin Fluoroquinolones should be avoided in patients with a history of myasthenia gravis. Neuromuscular blocking activity; may exacerbate muscle weakness.
Linezolid No information found to suggest a problem in myasthenia gravis.
Meropenem No information found to suggest a problem in myasthenia gravis.
Metronidazole No information found to suggest a problem in myasthenia gravis.
Micafungin No information found to suggest a problem in myasthenia gravis.
Tazocin (tazobactam & piperacillin) Neuromuscular blockade produced by muscle relaxants could be prolonged in the presence of piperacillin.
Teicoplanin No information found to suggest a problem in myasthenia gravis.
Temocillin No information found to suggest a problem in myasthenia gravis.
Tigecycline Due to a potential for weak neuromuscular blockade, care should be taken in administering tetracyclines to patients with myasthenia gravis.
Tobramycin Contraindicated in myasthenia gravis. As for gentamicin above; aminoglycosides may aggravate muscle weakness.
Trimethoprim No information found to suggest a problem in myasthenia gravis.
Vancomycin Concomitant use of vancomycin with muscle relaxants suxamethonium or vecuronium has been associated with the potential for enhanced neuromuscular blockade
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