MG and Antibiotics: What You Need to Know About Interactions and Risks

When you have myasthenia gravis, a chronic autoimmune disorder that weakens muscles by disrupting nerve-to-muscle signals. Also known as MG, it makes your body extra sensitive to certain drugs—especially antibiotics, medications used to treat bacterial infections. Some antibiotics can worsen muscle weakness, trigger breathing trouble, or even cause a medical emergency in people with MG.

Not all antibiotics are dangerous, but several are known to interfere with neuromuscular transmission. Fluoroquinolones, like ciprofloxacin and levofloxacin, are among the worst offenders—they’ve been linked to sudden muscle weakness and respiratory failure in MG patients. Aminoglycosides, including gentamicin and tobramycin, are equally risky, especially when given IV. Even macrolides, such as azithromycin and erythromycin, can cause problems, though less often. These drugs don’t just treat infection—they can block the same nerve signals that MG already damages, making weakness worse fast.

On the flip side, some antibiotics are generally safe for MG patients. Penicillins like ampicillin and amoxicillin, and cephalosporins like cephalexin, are often preferred because they don’t affect muscle function. But even then, it’s not just about the drug—it’s about dosage, route, and your overall health. If you’re dehydrated, on high doses, or already struggling with breathing, even safer antibiotics can tip the balance. Always tell your doctor you have MG before starting any new medication, even if it’s just for a simple infection.

What you’ll find below are real, practical guides from people who’ve been there—articles that break down which antibiotics to avoid, why some cause sudden collapse, how to spot early warning signs, and what alternatives actually work without risking your muscles. No guesswork. No fluff. Just clear, tested info to help you stay safe while treating infections.