Several common medication classes can cause charley horses, including diuretics (water pills), statins (cholesterol-lowering drugs), and certain hormone therapies. These aren’t rare side effects: up to 20% of statin users in real-world settings report muscle complaints, and diuretics are one of the most frequently cited drug triggers for nocturnal leg cramps. If you’ve started a new medication and noticed painful cramping in your calves or feet, especially at night, there’s a reasonable chance the two are connected.
Diuretics and Electrolyte Loss
Diuretics, commonly prescribed for high blood pressure and fluid retention, are among the most well-known cramp-causing medications. They work by flushing excess fluid from your body through increased urination, but they also pull essential minerals along for the ride. Low potassium, low magnesium, and simple fluid loss (volume contraction) all make muscles more prone to sudden, painful cramping.
Different types of diuretics cause problems through slightly different pathways. Loop diuretics like furosemide can lower calcium levels on top of depleting potassium and magnesium. Thiazide diuretics tend to spare calcium but still drain potassium and magnesium. Even potassium-sparing diuretics like amiloride, which are specifically designed to prevent potassium loss, have been linked to cramping. The one mechanism common to every class of diuretic is volume contraction: your body simply has less fluid to work with, and that alone can trigger cramps. This is why staying well-hydrated matters even more when you’re on a water pill.
Statins and Muscle Complaints
Statins are the most widely prescribed cholesterol-lowering drugs, and muscle problems are their best-known side effect. In clinical trials, somewhere between 1% and 5% of participants report muscle pain or cramping. But those trials tend to exclude people who are already prone to muscle issues, so the real-world numbers are higher. Studies in outpatient settings find that 9% to 20% of statin users experience muscle complaints, ranging from general soreness and stiffness to full charley horses.
Higher doses appear to increase the risk, though the exact threshold varies by person. The muscle symptoms can show up weeks or even months after starting treatment, which makes it easy to miss the connection. Some people notice cramps primarily at night or after exercise, while others feel a more constant achiness in the legs and arms. The discomfort typically resolves within a few weeks of stopping the medication, which helps confirm the link.
Non-statin cholesterol drugs aren’t completely off the hook either. Ezetimibe, often prescribed as an alternative for people who can’t tolerate statins, has been reported to cause muscle pain in some patients, including those who switched specifically because of statin-related muscle problems. The risk appears to be much lower than with statins, but it’s worth being aware of if you’re making a switch and the cramping continues.
Hormone Therapies and Bone Medications
Raloxifene, a medication used to prevent and treat osteoporosis in postmenopausal women, causes leg cramps at notably higher rates than placebo. In prevention studies, 5.5% of women on raloxifene reported leg cramps compared to 1.9% on placebo. In treatment studies, the gap was smaller but still significant: 9.2% versus 6.0%. Over eight years of follow-up, the difference remained statistically meaningful, making leg cramps one of the most consistent side effects of this drug alongside hot flashes.
Bisphosphonates, another class of osteoporosis drugs (including alendronate and risedronate), have a more complicated picture. Around 20% to 25% of weekly users report musculoskeletal side effects of some kind, but when researchers controlled for other factors, bisphosphonate users weren’t at significantly greater risk of musculoskeletal pain than people who had never taken these drugs. In other words, some of the muscle complaints in this group may be coincidental rather than caused by the medication itself.
When Cramps Are Something Different
Not every medication-related muscle spasm is a charley horse. Antipsychotic medications and certain anti-nausea drugs can cause a condition called acute dystonia, which involves sustained muscle contractions and abnormal postures. This looks different from a typical cramp. Dystonia usually affects the head and neck (causing the jaw to clench, the neck to twist, or the eyes to roll upward), tends to worsen when you move, and typically appears within seven days of starting a new medication or increasing the dose. A charley horse, by contrast, hits the calves or feet, lasts seconds to minutes, and strikes during rest or sleep.
If you develop unusual muscle spasms in your face, neck, or torso shortly after starting a new psychiatric medication, that’s a different problem from nighttime leg cramps and needs prompt medical attention.
What You Can Do About It
The most effective approach depends on which medication is causing the problem. For diuretic-related cramps, the issue is often fixable without changing your prescription. Staying well-hydrated counteracts the volume contraction that all diuretics share. Your doctor may check your potassium and magnesium levels and recommend supplements or dietary adjustments if they’re low. Foods rich in potassium (bananas, potatoes, beans) and magnesium (nuts, leafy greens, whole grains) can help fill the gap.
For statin-related cramps, the solution usually involves adjusting the dose or trying a different statin. Some statins cause fewer muscle problems than others, and lower doses may still control cholesterol while reducing side effects. Vitamin B complex supplementation has been suggested as a supportive measure for medication-related leg cramps, though the evidence is modest.
Regardless of the specific drug, a few practical habits can reduce cramping frequency. Gentle stretching before bed targets the calf muscles most prone to nighttime cramps. Keeping a glass of water on your nightstand addresses mild dehydration that builds overnight. If cramps are regularly waking you from sleep, that’s worth bringing up at your next appointment, because adjusting the medication, its dose, or its timing can often make a meaningful difference.