Hidden Drug Effects: Is Your Medication Causing Muscle Weakness?

What happens if something that was meant to improve your health has a negative side effect? Have you ever started taking a new medication only to discover that your muscles don't feel well weeks or months later? The new drug is probably the first thing that springs to mind when you try to figure out what might be wrong.

Perhaps you have trouble getting out of bed in the morning, struggle to lift groceries that would be easier on a good day, or feel weaker when climbing stairs. These are some of the symptoms associated with muscle weakness.

The purpose of medications is to improve our health, treat long-term illnesses, and even save lives. They may, nevertheless, occasionally have adverse effects, usually stated in the patient information leaflets that accompany these medications. Muscle weakness is an often-overlooked side effect of certain medications. Catching it early can prevent further complications. Let’s explore how certain medications may be affecting your muscles, what to watch for, and what you can do about it.

How Do Medications Cause Muscle Weakness?

Medications can cause muscle weakness in several ways:

• Autoimmune reactions: Immunotherapy or antimalarials may trigger the body to attack muscle tissue mistakenly.

• Direct muscle damage: Some drugs can damage muscle fibers, leading to weakness or pain, particularly at high doses.

• Drug Interactions: Some drugs interact with others, increasing the risk of side effects, including muscle weakness.

• Electrolyte Imbalance: Medications that affect potassium, magnesium, calcium, or sodium levels can disrupt muscle function. A fine balance of these electrolytes is required for proper muscle contraction.

• Hormonal disruption: Medications that affect the thyroid or adrenal glands can cause hormonal imbalances, which can weaken muscles.

• Nerve interference: Certain medications can interfere with nerve signals, thereby affecting nerve-muscle communication.

Symptoms and Signs

Although fatigue usually accompanies muscle weakness, muscle weakness differs from fatigue. Fatigue is a feeling of tiredness where you might lack the motivation to perform a task, but still possess the physical strength to do so if compelled. In contrast, muscle weakness is an actual reduction in physical strength, meaning your muscles genuinely lack the power to perform movements, regardless of your energy levels.

There are different types of muscle weakness, depending on the location of the affected muscle.

• Proximal: Affects muscles near your torso, like hips and shoulders.

• Distal: Affects hands, feet, or lower legs.

• Generalized: Weakness all over the body.

Other accompanying symptoms of muscle weakness include;

• Aching or soreness

• Difficulty climbing stairs, lifting objects, or getting up from a chair

• Low stamina

• Muscle cramps, spasms, or stiffness

Common Medications Linked to Muscle Weakness

You might be surprised to learn that the medications you take every day can contribute to muscle issues. While not everyone will experience this side effect, being aware can help you catch it early.

Here are some common medications that can cause or exacerbate muscle weakness.

Antiarrhythmic Medications

Drugs like amiodarone, used to manage irregular heart rhythms, can sometimes cause muscle weakness, especially in older people. One study showed that amiodarone caused nerve and muscle problems in a patient. The patient’s mobility function improved after the medication was discontinued.

Anticholinergics

Anticholinergic drugs such as amitriptyline for depression, oxybutynin and solifenacin for overactive bladder, and diphenhydramine for allergies can cause muscle weakness as a side effect. The drugs prevent involuntary muscle movements. However, they can sometimes interfere with nerve signals to the muscles, leading to weakness.

Antimalarial Medications

Chloroquine and hydroxychloroquine are often used to treat malaria or autoimmune diseases such as lupus. They are effective and can knock you out quickly. It can cause muscle weakness and make daily activities like rising from a chair or lifting objects more challenging. The symptoms usually resolve after the dosage is complete.

Beta-blockers

Used to treat high blood pressure and heart problems, beta-blockers, like metoprolol and atenolol, can cause fatigue and muscle weakness in some patients, especially when combined with other medications.

Cancer Treatments

Cancer treatment usually involves using numerous medications, chemotherapy agents such as doxorubicin, cisplatin, and fluorouracil are some of them.

Unfortunately, they can damage muscle tissue or nerves, leading to muscle weakness. Newer immunotherapy agents like nivolumab and pembrolizumab may trigger rare autoimmune reactions that cause inflammatory muscle damage.

Colchicine (for Gout)

Colchicine is used to treat high levels of uric acid in the body. It targets the stiffness of the joints and reduces the pain that comes with it. However, it can be toxic to muscles at high doses. Specifically, it has been shown to cause rhabdomyolysis in patients.

Corticosteroids

Corticosteroid drugs like prednisone are used for a wide range of inflammatory conditions. However, long-term use can lead to steroid muscle damage. This condition often affects the upper legs and arms. This usually develops gradually and can be worsened by higher doses or prolonged treatment.

Diuretics

Diuretic drugs like furosemide and hydrochlorothiazide are used to lower blood pressure by increasing fluid output. However, they have been shown to lead to low potassium levels, a condition known as hypokalemia, which often presents as muscle cramps and weakness.

Fluoroquinolone Antibiotics

Fluoroquinolone antibiotics such as ciprofloxacin (cipro) and levofloxacin can cause muscle weakness by damaging tendons (leading to tendonitis or rupture), affecting nerve signals to muscles, and reducing energy production in muscle cells. This can result in pain, weakness, or fatigue, especially in older adults or when used in combination with steroids.

Muscle Relaxants

It might sound ironic, but medications like baclofen, tizanidine, and orphenadrine, while designed to relax tight muscles, can sometimes cause overall muscle weakness and sedation. Sometimes you need some downtime for the medications to take effect.

Statins (Cholesterol-lowering drugs)

Medications such as atorvastatin and simvastatin are effective in reducing cholesterol levels and lowering the risk of heart disease. But they’re also among the most commonly reported drugs linked to muscle pain and weakness. Some people develop a condition called statin-induced muscle problems, which can range from mild soreness to significant weakness.

Other medications

Here are some additional drugs to be mindful of:

• Certain antipsychotics and antiepileptics (e.g., lamotrigine, phenytoin)

• Cimetidine (Tagamet)

• D-penicillamine (for Wilson’s disease)

• Illicit drugs like alcohol, cocaine, and heroin can also directly damage muscles.

• Interferon (used in MS and cancers)

• Leuprolide (Lupron) – hormone therapy

• Omeprazole (for acid reflux)

Thus, there are many medications that can possibly cause muscle weakness. They can do so through their mechanism of action or how your body reacts to them. Be sure to check the leaflets for any indication that muscle weakness is a side effect.

Management of Drug-Induced Muscle Weakness

If you suspect that any of your medications is causing muscle weakness, here are some ways to manage it:

Get Regular check-ups

Stay close to your healthcare provider. Ensure you attend regular check-ups so they can review your medications and provide advice on dosage and medication review.

Lifestyle Changes

You can also alleviate muscle weakness by making small adjustments to your lifestyle. Activities such as gentle strength training, stretching, and movement can help rebuild muscle over time.

Also, ensure you always eat a balanced diet. Ensuring proper intake of protein, potassium, magnesium, and vitamin D can support muscle health. You can also get supplements with these nutrients.

Medication Adjustment

Sometimes, muscle weakness is a sign that the dose of your medication is not right for you. If you suspect a medication is affecting your muscles, don’t stop taking it suddenly. Instead, work with your doctor to evaluate the situation.

• Alternative Medications: There may be other drugs that can treat your condition with fewer side effects. Often, the medication has a generic version or an alternative chemical structure. The modification of your medicine means you eliminate muscle weakness.

• Avoid drug combination: Combining certain medications can sometimes increase the risk of muscle problems. For instance, the combination of statins with colchicine can cause muscle breakdown.

• Dose Reduction: Sometimes a lower dose can improve your symptoms without sacrificing the effectiveness of the medication. This way, you get relief from your muscle weakness but continue your medication.

Conclusion

Medications can do a lot of good, but they’re not without side effects. Muscle weakness is one of those symptoms that can creep up on you slowly. You can easily overlook them or blame them on aging, stress, or just “being tired.”

If you’re feeling weaker than usual and can’t quite explain why, it’s worth checking your medicine cabinet and having a conversation with your healthcare provider.