Q: I frequently have leg cramps that wake me up from sleep. How can I quickly stop the cramps, and are there ways to prevent them?
A: Few things are more jarring to a night's sleep than a sudden cramp in your calf. By the way, you have lots of company. Although nocturnal leg cramps can strike people at any time of life, they become more common with age. Among people over 50, about half report having leg cramps, a third say they are awakened by cramps at night, and 15 percent report weekly episodes.
Leg cramps are muscle spasms caused by "mini-seizures" of motor neurons (nerves that power muscle contractions). They are common among people with foot problems like flat feet or high arches, metabolic disorders, or neurological conditions such as Parkinson's disease or neuropathy (nerve damage).
However, most cramps strike people who are otherwise healthy. Dehydration and electrolyte imbalances such as low blood potassium or magnesium levels (a common side effect of diuretics) can increase the risk of cramping.
To stop a foot or cramp once it happens, lean over and grab your toes, then slowly bend your foot back toward your head. Hold for about 20 seconds then release it. Repeat as needed. If that doesn't help, you can try rubbing the cramp with ice wrapped in a towel. Some people find more relief with a heating pad placed on the cramp.
Despite the lack of a scientifically proven and safe therapy to prevent recurrent nighttime leg cramps, a few approaches may be worth trying.
Start with stretching exercises. Stand about 2 feet from a wall. Lean forward, keeping your legs straight and feet flat on the floor. You should feel the stretch but it should not be painful. Hold the position for 20 seconds and release. Repeat the stretch four to five times.
Ideally try to do this four times per day for the first couple weeks at least. The most important time to stretch is before bed.
Other preventive measures you can try include avoiding dehydration, wearing well-fitting supportive footwear, and keeping the bedding at your feet loose during the night. Although the evidence isn't strong, some people find that taking a daily vitamin B complex helps, or consider over-the-counter diphenhydramine (Benadryl) before bedtime.
Right now there are no FDA-approved medications for leg cramps. The one drug with solid evidence for reducing the frequency of muscle cramps is quinine. However, the FDA has issued repeated warnings against using quinine to prevent or treat leg cramps because it may cause serious side effects. Although doctors can still prescribe quinine, it is recommended only when cramps are disabling and the person understands the significant risks.
(Howard LeWine, M.D., is an internist at Brigham and Women's Hospital in Boston and assistant professor at Harvard Medical School. For additional consumer health information, please visit www.health.harvard.edu.)