Cramps - Causes and Treatment

Night cramps, leg cramps, frequent cramps, bananas for cramps... This paper will explain what cramp is, why it arises and how to prevent its occurrence.



A cramp is an involuntary contraction or spasm of the muscles, usually very painful, which can last from several seconds to several minutes. The cramp may affect one or more muscles at once.

Any voluntary muscle control can present these contractions. The most common are:

• Calves
• Thigh muscles
• Feet
• Hands
• Neck
• Abdomen

It is believed that the basic cause of cramp is a hyperexcitation of the nerves that stimulate the muscles. This is typically caused by:

• Vigorous physical activity (cramping can occur during or after physical exertion)
• Dehydration (major cause in the elderly and those who use diuretics)
• Hydroelectrolytic changes, especially depletion of calcium and magnesium
• Pregnancy (usually cramp is secondary to low magnesium levels)
• Bone fracture (such as self-protection, the muscles around the injury twitch involuntarily)
• Metabolic disorders such as diabetes, hypothyroidism, hypoglycemia and alcoholism
• Neurological disorders: Parkinson's, motor neuron disease or primary disease of the muscles (myopathy)
• Venous insufficiency and varicose veins in the legs
• Long periods of inactivity (sitting in awkward position, for example)
• Structural changes such as flat foot and genu recurvatum (knee hyperextension)
• Hemodialysis
• Liver cirrhosis
• Deficiency of vitamin B1, B5 and B6
• Anemia

Much has been said about potassium depletion as a cause of cramps. Actually, hypokalemia (low blood potassium levels) may even cause involuntary contractions, but its main symptom is muscle weakness or paralysis. Calcium and magnesium are important and common causes of cramps.

Some drugs may be the cause of heat cramps:

• Diuretics, especially furosemide (Lasix)
• Donepezil (used for Alzheimer's disease)
• Neostigmine (used for myasthenia gravis)
• Raloxifene (used for osteoporosis and breast cancer)
• Medications for hypertension, especially nifedipine (Adalat)
• Bronchodilators for asthma such as salbutamol
• Remedies for cholesterol such as clofibrate and lovastatin

In people over 60, frequent cramps could be signs of atherosclerosis, which leads to decreased blood flow to particular muscle group by outflow obstruction by cholesterol plaques.


To avoid cramping a good session of stretching before and after exercise should be performed, especially for the sedentary way of life. Proper hydration before, during and after the exercises is also important. Try to avoid exercise on very hot days.

There is a group of people who have night cramps, especially in the lower limbs (calf and feet in general). It is customary to call these people having nocturnal idiopathic cramp (idiopathic means without apparent cause). They are usually individuals with a family history of cramps and you cannot detect any change that justifies the frame. In this group, a program of stretching 15 minutes before bedtime is recommended, preference for foods rich in calcium and magnesium, maintaining good hydration throughout the day and avoiding a sedentary lifestyle. Some people need special shoes to prevent involuntary contractions and cramps in the legs.

Stretching seems to be the best method to prevent cramps, especially when occurring in the legs. Importantly, it will not be an overnight that stretching will bring results. It takes at least a few weeks with daily stretching muscles to have more resistance to involuntary contractions.

Proper hydration and frequent stretching solve problems of most people with idiopathic cramps. The best way to control the degree of hydration of the body is via the urine color. People have dehydrated urine yellowish and usually with very strong smell, while a hydrated body produces clear and no smell urine. There are some medications such as vitamin E, B complex, verapamil, chloroquine and gabapentin that can help in specific cases, but that should only be taken after medical evaluation.

Tonic water has quinine small amounts of a substance that also seems to prevent cramps. There are reports of improvement of night cramps after ingesting a few days tonic water at night.


Patients with renal failure on hemodialysis are another case. A cramp is a sign of reduced blood flow to the affected muscle. It usually occurs due to excess fluid removed during hemodialysis sessions or high doses of antihypertensive drugs. Patients with cramps that do not use antihypertensives should increase their dry weight (weight after a dialysis session). Those with cramping, but using remedies for hypertension, should attempt to suspend them or to lower the dose even if the pressure is still poorly controlled.


This story with the banana is a bit confusing. The fruit is rich in potassium, carbohydrates (glucose) and water. During physical exertion there is a great demand of muscles for energy (glucose). After some time of exercise the muscle depletes its reserves of glucose and begins to use other means to generate energy. One cause of cramps is the accumulation of lactic acid, which is the "garbage" after metabolic energy generation with low glucose utilization. Good hydration helps to "wash" the excess lactic acid circulation and prevent cramps.

So theoretically the fruit helps because the banana restores potassium levels, moisturizes and provides energy (glucose) to the muscles. This is true for exercise-induced cramps. However, this trick does not work with many people. The answer seems to be individual, but as a banana does not hurt anyone, it is worth testing.