Medications That May Cause Muscle Weakness as a Side Effect

Certain medications can cause drug-induced myopathy (muscle disease). The symptoms can range from mild to severe and may include muscle weakness, pain, inflammation, stiffness, spasms, and cramps. There are different types of myopathies. We will talk about drug-related myopathies, where certain medications interfere with muscle structures and function, leading to the symptoms of myopathy. Please continue reading to learn about some of the medicines that can cause muscle weakness as a side effect.

What medications can cause myopathy?

Some of the medicines that can cause drug-induced myopathy include:

Cholesterol-lowering drugs such as statins (for example, simvastatin and atorvastatin) and fibrates (for example, fenofibrate, gemfibrozil)
Antiarrhythmic medicines used to treat heart rhythm problems (for example, amiodarone and procainamide)
Corticosteroids, such as prednisone, especially at high doses and for prolonged periods of time
Medicines used to treat high blood pressure, such as labetalol
Antimalarial medicines, such as chloroquine and hydroxychloroquine
Loop diuretics and thiazide diuretics (water pills), such as furosemide and chlorthalidone
Medicines used during general anesthesia, such as propofol
Immune checkpoint inhibitors used for cancer treatment (for example, nivolumab, pembrolizumab, atezolizumab)
Immunosuppressive agents used to prevent organ rejection after transplant (for example, cyclosporine)
Antiretrovirals, such as zidovudine, used to prevent and treat HIV
Chemotherapy agents such as vincristine.
Tumor necrosis factor-alpha inhibitors such as etanercept, adalimumab, infliximab, and others
D-penicillamine, a chelating agent used to treat Wilson’s disease
Antiepileptic drugs such as lamotrigine and phenytoin
Omeprazole, a medication for gastroesophageal reflux disease (GERD)
Gout medicines such as colchicine

Keep in mind that not everyone who takes the above-listed medications develops myopathy (muscle disease) with symptoms such as muscle weakness. Some of these medications are widely prescribed and do not cause muscle problems in the vast majority of patients. However, there have been a small number of cases of muscle problems (drug-induced myopathy) linked to these drugs. If this worries you, you should discuss the risks and benefits of your medication with your doctor. You should not stop taking medication because disruption in therapy can lead to serious health problems.

Keep in mind that certain health conditions and lifestyle factors, such as excessive alcohol consumption, can also contribute to the symptoms of myopathy.

Why do medications affect your muscles?

Medications can affect your muscles in many different ways. Certain medications, for example, statins and fibrates, as well as alcohol, cause necrotizing myopathy characterized by the death of muscle fibers. Other mechanisms by which drug-induced myopathy can occur include inflammatory reactions (for example, statins and D-penicillamine). Mitochondrial myopathies have been linked to antiretroviral drugs like zidovudine, which affect the genetic material in muscle cells. Some medications cause muscle weakness by causing hypokalemia or low potassium levels (for example, diuretics or water pills).

Do blood pressure medications cause muscle weakness?

Fatigue and weakness are known side effects of blood pressure medications such as beta blockers. There are case reports of muscle pain related to labetalol use. However, muscle weakness is not a common adverse effect of blood pressure meds.

Which medical conditions can cause muscle weakness?

In addition to drug-induced myopathy, muscle weakness is a common symptom in a wide range of health conditions, including anemia, viral infections, diabetes, underactive thyroid (hypothyroidism), overactive thyroid (hyperthyroidism), electrolyte imbalance, fibromyalgia, chronic fatigue syndrome, Addison’s disease, kidney disease, sleep disorders, and neurological conditions.

Remember, muscle weakness is not always a symptom of a serious health condition. Poor sleep quality, stress, and menstrual periods for women can lead to weakness, physical exhaustion, and reduced exercise performance.

You should speak to your doctor if you have ongoing or worsening muscle weakness, especially if muscle weakness is accompanied by other symptoms such as difficulty breathing, skin rash, dizziness, fever, nausea, vomiting, loss of appetite, sore throat, cough, other signs of infection, joint pain, sweating, weight loss, agitation, or confusion. Your doctor can make a diagnosis and recommend the appropriate treatment.

If the cause of your muscle weakness is found to be due to a medication side effect, your doctor may lower the dose of the offending medication, switch you to another medicine, or discontinue treatment.

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