What Drugs Aggravate Myasthenia Gravis? A Comprehensive Guide

October 8, 2025 •

4 min read

In up to 19% of myasthenia gravis (MG) exacerbations, the trigger is a pharmaceutical intervention [1.5.1]. Understanding what drugs aggravate myasthenia gravis is crucial for managing this autoimmune condition, as many common medications can interfere with neuromuscular transmission and worsen symptoms [1.2.2].

Quick Summary

A comprehensive overview of medications known to worsen myasthenia gravis symptoms. This includes specific antibiotics, cardiovascular drugs, anesthetics, and others that can interfere with neuromuscular function and potentially trigger an MG crisis.

Key Points

Black Box Warnings: Fluoroquinolone antibiotics (e.g., ciprofloxacin) and telithromycin have the strictest FDA warnings for MG patients and should be avoided [1.3.3].
Antibiotics are a Major Risk: Aminoglycosides (e.g., gentamicin), macrolides (e.g., azithromycin), and fluoroquinolones are the antibiotic classes with the strongest evidence for worsening MG [1.4.1, 1.4.2].
Cardiovascular Drugs: Beta-blockers (e.g., propranolol) and calcium channel blockers (e.g., verapamil) can increase muscle weakness and should be used with caution [1.3.2, 1.3.5].
Anesthesia is a Special Concern: MG patients are highly sensitive to non-depolarizing muscle relaxants used in surgery; regional anesthesia is often preferred [1.6.1, 1.6.3].
IV Magnesium is Dangerous: Intravenous magnesium can severely block neuromuscular transmission and precipitate a myasthenic crisis [1.8.6].
Steroid Initiation: While a primary treatment, starting corticosteroids at a high dose can cause a paradoxical, temporary worsening of MG symptoms [1.2.2].
Patient Advocacy is Key: Always inform all healthcare providers of your MG diagnosis and discuss any new medication with your neurologist before starting it [1.2.2].

Understanding Myasthenia Gravis and Medication Risks

Myasthenia gravis (MG) is a chronic autoimmune disorder where the body's immune system mistakenly attacks and damages the communication points between nerves and muscles (the neuromuscular junction) [1.6.1]. Specifically, antibodies often target acetylcholine receptors, reducing their number and function. This impairment leads to the hallmark symptoms of MG: fluctuating muscle weakness and fatigue that worsens with activity [1.6.1].

Because the neuromuscular transmission in MG patients is already compromised, any drug that further interferes with this delicate process can exacerbate symptoms, sometimes severely [1.2.2]. The effect can be so significant that it unmasks previously undiagnosed MG or, in severe cases, leads to a myasthenic crisis—a life-threatening condition with profound respiratory muscle weakness [1.3.6, 1.6.1]. For this reason, patient and physician awareness of high-risk medications is a critical component of safe MG management.

Drugs with Black Box Warnings

The U.S. Food and Drug Administration (FDA) issues a "black box warning" for drugs with serious safety risks. For patients with MG, this is the strongest possible caution.

Fluoroquinolone Antibiotics: This class of broad-spectrum antibiotics, including ciprofloxacin, levofloxacin, and moxifloxacin, carries a black box warning due to its association with worsening MG [1.8.6]. They are thought to directly block the acetylcholine receptor's ion channel [1.5.2].
Telithromycin: This ketolide antibiotic, though less common now, also has an FDA black box warning and should not be used in MG patients [1.8.6].

High-Risk Drug Classes for MG Patients

Beyond those with black box warnings, numerous other drug classes are known to pose a risk. They should be avoided or used with extreme caution and close monitoring by a neurologist.

Antibiotics

Infections are a common trigger for MG exacerbations, but the antibiotics used to treat them can also be problematic [1.3.5].

Aminoglycosides: Drugs like gentamicin, neomycin, and tobramycin are well-known to cause MG exacerbation. They can block the release of acetylcholine from the nerve terminal and also decrease the muscle's sensitivity to it [1.5.2]. Gentamicin is considered contraindicated [1.4.7].
Macrolides: Commonly prescribed antibiotics such as azithromycin, clarithromycin, and erythromycin can worsen MG and should be used cautiously [1.8.6]. Azithromycin (often given as a "Z-pack") is one of the most common antibiotics reported to precipitate a hospital admission for MG exacerbation [1.4.6].

Cardiovascular Medications

Many drugs used to treat heart conditions and high blood pressure can affect the neuromuscular junction.

Beta-Blockers: This class, including propranolol and metoprolol (even in eye drop form like timolol for glaucoma), can potentiate muscle weakness and may worsen MG [1.2.5, 1.8.6]. They have been associated with a 2.7-fold increased risk of MG aggravation [1.5.1].
Calcium Channel Blockers: Medications like verapamil may cause increased weakness by reducing the release of acetylcholine [1.3.2, 1.5.1].
Antiarrhythmics: Class Ia agents like procainamide and quinidine should be used with caution as they can increase weakness [1.3.5].
Statins: Used to lower cholesterol, statins like atorvastatin and simvastatin can occasionally worsen or precipitate MG, though the risk is considered low for most patients [1.5.4, 1.8.6].

Anesthetics and Muscle Relaxants

Surgical procedures require careful planning for MG patients.

Neuromuscular Blocking Agents (NMBAs): MG patients are highly sensitive to non-depolarizing NMBAs (e.g., rocuronium, vecuronium) and may experience prolonged paralysis [1.6.3]. Conversely, they can be resistant to depolarizing NMBAs like succinylcholine [1.6.3]. The use of these agents should be avoided if possible or used in reduced doses with careful monitoring [1.6.3, 1.6.5]. The introduction of reversal agents like sugammadex has improved safety [1.6.6].
Botulinum Toxin (Botox): This agent works by blocking acetylcholine release and should be avoided, as it can cause local and distant muscle weakness mimicking or worsening MG [1.8.6, 1.5.2].
Inhaled Anesthetics: Agents like sevoflurane and desflurane can cause some degree of muscle relaxation and should be used with care [1.6.1].


Category	High-Risk Examples	Lower-Risk Alternatives / Considerations
Antibiotics	Fluoroquinolones (Ciprofloxacin), Aminoglycosides (Gentamicin), Macrolides (Azithromycin) [1.4.1]	Penicillins and cephalosporins are often preferred when appropriate for the infection [1.3.5].
Cardiovascular	Beta-Blockers (Propranolol), Calcium Channel Blockers (Verapamil), Procainamide [1.3.2, 1.3.5]	Angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) seem to be safe [1.5.5].
Anesthetics	Non-depolarizing neuromuscular blockers (rocuronium), Botulinum Toxin [1.6.3, 1.8.6]	Local or regional anesthesia is preferred when possible. If general anesthesia is needed, avoiding NMBAs is ideal [1.6.1, 1.6.3].
Psychiatric	Lithium, certain antipsychotics (Chlorpromazine), Benzodiazepines (Diazepam, Lorazepam) [1.3.5, 1.7.1]	SSRIs like fluoxetine and sertraline are generally considered safer options, but require monitoring [1.7.3].
Other	Magnesium (especially IV), Quinine, D-penicillamine [1.2.2, 1.8.6]	Oral magnesium in multivitamins is generally not an issue; high doses and IV forms are the primary concern [1.3.5].

Other Significant Medications

Magnesium: Intravenously administered magnesium is particularly dangerous and should be avoided unless absolutely necessary, as it can precipitate a myasthenic crisis [1.8.6]. It directly inhibits acetylcholine release [1.5.2].
Psychiatric Medications: Lithium, benzodiazepines (which can cause respiratory depression), and some antipsychotics can exacerbate MG symptoms [1.3.5, 1.7.6].
Corticosteroids: While a cornerstone of MG treatment, starting steroids at a high dose can cause a temporary but significant worsening of symptoms in the first few weeks [1.2.2, 1.8.6]. Treatment is typically initiated at a low dose and escalated gradually [1.2.2].
Antimalarials: Chloroquine and hydroxychloroquine, used for malaria and some autoimmune conditions, may worsen MG [1.2.2].
D-penicillamine: This drug, used for Wilson's disease and rheumatoid arthritis, is strongly associated with inducing MG and should be avoided [1.8.6].

Conclusion

Managing myasthenia gravis involves a partnership between the patient and their healthcare team. Many physicians may be unaware of the extensive list of drugs that can negatively impact MG [1.2.2]. Therefore, it is vital for patients to be their own advocates. Always inform every healthcare provider, including dentists and emergency personnel, of your MG diagnosis. Before starting any new medication, whether prescription or over-the-counter, consult with your neurologist. Carrying a list of cautionary drugs, such as the one provided by the Myasthenia Gravis Foundation of America, can be a life-saving tool in an emergency [1.2.2, 1.8.6]. While some risky medications may be necessary in certain situations, this decision must be made by weighing the benefits against the potential for a severe MG exacerbation [1.2.2].

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional before making any decisions about your treatment. Click here for an authoritative list of cautionary drugs from the Myasthenia Gravis Foundation of America.

Frequently Asked Questions

Fluoroquinolones (like ciprofloxacin and levofloxacin) and the ketolide telithromycin carry FDA black box warnings and should be avoided [1.3.3]. Aminoglycosides (like gentamicin) and macrolides (like azithromycin) also pose a significant risk and should only be used with extreme caution if no alternative is available [1.4.1, 1.4.7].

Some blood pressure medications, particularly beta-blockers (e.g., metoprolol) and calcium channel blockers (e.g., verapamil), can worsen MG symptoms [1.3.2]. However, the decision to use them depends on a risk-benefit analysis with your cardiologist and neurologist. Other classes, like ACE inhibitors, appear to be safer [1.5.5].

Yes, but it requires careful planning. Anesthesia must be managed by a team aware of your condition. MG patients have altered responses to muscle relaxants [1.6.3]. Regional or local anesthesia is often preferred. If general anesthesia is needed, specific protocols are used to minimize risks [1.6.1].

Statins have been reported to occasionally worsen or precipitate MG, but this is rare [1.5.4]. Most patients can take statins without issue. It is recommended to use the lowest effective dose and monitor for any new or worsening muscle weakness when starting the medication [1.8.6].

Yes. Some over-the-counter products can be risky. For example, laxatives or antacids containing high amounts of magnesium should be used with caution [1.4.3]. Quinine, sometimes found in tonic water, can also aggravate MG symptoms [1.3.2]. Always check with your doctor before taking new OTC medications or supplements.

Certain psychiatric drugs, like lithium and benzodiazepines (e.g., diazepam), can worsen MG symptoms or cause respiratory depression and should be used with extreme caution or avoided [1.7.2, 1.7.6]. Some antidepressants, like certain tricyclics (amitriptyline), may also be problematic, while SSRIs (e.g., sertraline, fluoxetine) are generally considered safer options under medical supervision [1.7.3].

Corticosteroids like prednisone are a primary treatment for suppressing the autoimmune response in MG. However, when treatment is initiated at a high dose, they can cause a temporary paradoxical worsening of weakness in the first couple of weeks [1.2.2, 1.8.6]. To avoid this, doctors usually start with a low dose and increase it gradually [1.2.2].