Why Does My Foot Cramp Up and Leave Me in Agony?

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Photo: Arman Zhenikeyev/Corbis

The human body is both amazing and terrible. Not only can it do things like heal its own wounds and circulate up to 2,000 gallons of blood per day, but it can also make one foot scrunch up like a hobbit claw at random and cause a brief period of excruciating pain. You try to will your foot open but are terrified to discover that its contractions are out of your control, as if possessed. If you're lucky, it's over quickly and you think, Well, that was freaky, then go about your business. If you’re unlucky, this happens enough that it’s no longer a minor annoyance — it’s slowly driving you crazy.

The good news is that if you’re otherwise healthy, it’s usually just a muscle cramp, says Janice Wiesman, M.D., a clinical associate professor of neurology at New York University School of Medicine. Dr. Wiesman, who’s a neuromuscular expert and member of the American Academy of Neurology, says that even though these spasms are super-common, doctors don’t know exactly what causes them. That’s because most of them — including torturous charley horses in your calves — aren’t serious and don’t really warrant studying, and conducting such research would be difficult.

“If someone has a cramp, do you stick an electrode in their brain to see if the motor cortex is overactive?” she says. “I guess you could do a functional MRI; it just hasn’t been done as far as I know.” Plus, these tests might not turn up anything if someone isn’t currently in the throes of a cramp.

Experts’ best guess is that your nerves simply go a little haywire and cause muscle contractions, and some believe it’s made worse by nerve diseases like neuropathy and electrolyte imbalances. The latter could be the result of run-of-the-mill dehydration or could be caused by certain medications, like albuterol inhalers for asthma or statins for cholesterol, Dr. Wiesman says. Pregnant women often say they get foot cramps and that’s likely because your blood vessels retain more fluid when you’re expecting, which dilutes electrolyte levels. Even a pinched nerve in your back or neck could cause cramps in your extremities, she says. (People with Parkinson’s or Huntington’s disease can also suffer from cramps but that’s due to a movement disorder called dystonia.)

There is one case when cramps may be more than just a random nerve snafu. “The time to be concerned is if the cramps come on only with exercise,” she says. If it just happens during or immediately after working out, it could indicate low thyroid function or some rare metabolic muscle diseases and you should talk to a doc.

Staying well-hydrated and wearing shoes with good arch support could help prevent them. If you’re suffering from a nasty clench, she says that getting up and walking around is usually the best course of action, but she also recommends slowly stretching the muscle in question. So if it’s your foot, try pulling your toes up toward your shin. Other remedies are more individual. “Some people find putting a cold pack on the muscle helps; other people find that getting into a hot shower helps. You just have to try 'em out and see what works for you.”

Some people tend to experience cramps in their feet or legs at night so stretching before bed could help. You might have read stories online about treating cramps with quinine pills, but don’t even try to get your doc to write you a script, Dr. Wiesman says. The FDA first advised against this off-label use of malaria drug Qualaquin in 2006 because of the small chance that it can cause serious clotting and heart problems, but some doctors still prescribe it. Yes, tonic water contains quinine, but the amount is so small now that it wouldn’t do much of anything. You can also try taking a magnesium supplement (it’s an electrolyte), but it’s probably best to run that past your doctor first.

If you’ve tried everything and your cramping feet are making you nuts, there’s an interesting remedy you can ask a neurologist about: Botox injections. It’s a tiny dose used off-label that doctors consider to be safe. “It’s not a standard treatment — botulinum toxin is in no way indicated by the FDA for this treatment — but it would work.” Hope your feet aren’t ticklish!