Quinine Benefits and Dangers for Malaria Treatment and Leg Cramps
What Is Quinine?
Quinine is a bitter chemical present in the bark of cinchona trees, which are native to South America. Multiple species of the genus Cinchona produce the chemical. Quinine is used as a medicine to treat malaria. It's also used in much lower doses to provide the bitter taste of tonic water.
Some people take quinine to help their nighttime leg cramps, but health agencies say that it's not advisable to use the chemical for this purpose. Quinine can cause a range of side effects, some of which may be dangerous. The only recommended use of the chemical at the moment is as an antimalarial medication.
Cinchona bark is sometimes known as Jesuits' bark or powder. The Jesuits introduced the plant to Europe from South America
Quinine is a natural chemical but can also be made synthetically. It's classified as an alkaloid. Alkaloids have a ring containing at least one nitrogen atom in their structure. They often have noticeable effects on the human body. Examples of alkaloids that have significant effects on humans include nicotine, caffeine, and morphine. The name of an alkaloid often ends in "ine".
If a glass of tonic water is exposed to sunlight, it will emit a faint blue glow. The action of the ultraviolet rays in sunlight on the quinine in the tonic water is responsible for this glow. Quinine is fluorescent. A fluorescent substance emits light of one colour when it's exposed to light of another colour (or to another form of electromagnetic radiation). If tonic water is exposed to a stronger UV light source than sunlight, it will emit a brighter glow.
The Cause of Malaria
Malaria is caused by a one-celled parasitic organism called Plasmodium. Malaria parasites enter a person’s blood in the saliva of an infected Anopheles mosquito when the insect bites its victim. The bite delivers saliva containing an anticoagulant. The anticoagulant stops blood from clotting and allows the mosquito to withdraw liquid blood.
Once the parasites have entered the body of their host they invade the liver cells, where they reproduce. After this reproduction the parasites enter the red blood cells. Inside the red blood cells the parasites continue to multiply. The cells eventually burst open, releasing new parasites, which can then infect more cells. Infected red blood cells all open at about the same time, releasing toxins that cause the victim to experience the typical chills, fever, headache, and muscle pain of malaria.
How Does Quinine Destroy the Malarial Parasite?
Quinine is best known as an antimalarial drug. Until the 1940s, cinchona bark and quinine were the best treatments for malaria. Quinine is still used to treat the disease today, but other drugs are sometimes preferred.
Plasmodium breaks down the hemoglobin in red blood cells for food. Hemoglobin is the red pigment that transports oxygen in the blood. As Plasmodium digests hemoglobin, it releases a toxic substance called heme from the hemoglobin. The parasite converts this toxin into a substance called hemozoin or malarial pigment, which is nontoxic. It’s thought that quinine inhibits one of the parasite’s enzymes, preventing the conversion of heme into malarial pigment. The heme therefore kills the parasite.
The malaria parasite exists in different forms in different stages of its life cycle. Quinine is only active against one form of the parasite, so malaria symptoms may reappear if quinine therapy is stopped.
The Malaria Parasite's Life Cycle in the Human Body
Side Effects of Quinine Treatment: Cinchonism
Quinine treatment for malaria can be very helpful but often results in a condition called cinchonism. Symptoms of mild cinchonism include headache, nausea, vomiting, abdominal pain, diarrhea, sweating, confusion, and dizziness. A person may also experience blurred vision, a rash, tinnitus (ringing in the ears), and the loss of high-frequency hearing. These symptoms disappear once quinine therapy is stopped.
Quinine also stimulates the release of insulin from the pancreas. Insulin is the hormone that triggers blood glucose (or blood sugar) to enter cells. Too much insulin causes hypoglycemia, which is an abnormally low level of glucose in the blood.
Severe cinchonism produces serious effects such as heart arrhythmia, blindness, a decreased number of blood platelets, kidney failure, low blood pressure, and anaphylaxis (a life-threatening and body-wide allergic response). Quinine can also interfere with the action of other drugs which a person is taking.
Malaria can be dangerous for a pregnant woman and for her fetus, so it must be treated. If a pregnant woman is given quinine as a treatment, the dose and the woman's response to the medication should be carefully monitored.
Malaria is one of the world's major health problems. Many antimalarial drugs are available, including quinine, which may be used on its own or in combination with other medications.
The antimalarial drug or drugs of choice depends on several factors, including the species of Plasmodium involved, the resistance of the parasite to the drug, the mechanism of action of the drug, and the condition of the patient. The development of parasite resistance to a particular medication is a frequent problem.
Doctors have to prescribe the medications that are both widely available and effective in their area. In some parts of the world they may be limited in their choice. Artemisinin in combination with another drug is often considered to be the best treatment for malaria today, but there are signs that the parasite is developing resistance to the drug.
Facts About Malaria From WHO
In 2016, an estimated 216 million cases of malaria occurred worldwide. There were an estimated 445 000 deaths from malaria globally, compared to 446 000 estimated deaths in 2015.— World Malaria Report 2017 from the World Health Organization, or WHO
Quinine and Leg Cramps
Quinine has been used to treat the painful leg cramps that some people experience at night. This is an off-label use of the medication, however. An off-label use is one that hasn't been approved by a regulatory agency (such as the FDA or Food and Drug Administration in the United States).
A leg cramp is a sudden and painful contraction of a muscle that lasts from seconds to minutes. The pain is usually in the calf but may develop in the thigh or foot instead. It often appears just before a person falls asleep. The cramps may occur on their own or may be accompanied by arthritis or restless legs syndrome. The likelihood of experiencing leg cramps increases as we age.
Quinine may reduce the excitability of the nerves that control the leg muscles. The results of clinical trials to test the effects of quinine on leg cramps have been mixed, however. Some experiments suggest that quinine can help while others conclude that the chemical has no effect.
Quinine tablets must be obtained by prescription in the United States. The FDA doesn't recommend the use of quinine for leg cramps due to the potential for serious side effects, including heart rhythm abnormalities and thrombocytopenia (a low platelet level). The NIH or National Institutes of Health warns people that they shouldn't use quinine to either treat or prevent nighttime leg cramps.
A dilute source of quinine can be found in grocery stores, Quinine is added to tonic water in very small quantities to produce the bitter taste that is enjoyed in some alcoholic drinks.
In British colonial times, tonic water had a much higher quinine content than today and was used to treat malarial symptoms. It really was a “tonic” water. Quinine is so bitter that drinking tonic water can cause vomiting unless the solution is very dilute or unless the taste of quinine is masked by sugar and flavourings.
The FDA limits the amount of quinine in tonic water today. A glass of tonic water contains around 20 mg of quinine, which is much less than a normal therapeutic dose. Even so, there are anecdotal reports of people with nighttime leg cramps who have drunk tonic water before going to bed and have been relieved of their cramps. The Harvard Health reference source mentioned below says that drinking a few ounces of tonic water "isn't likely" to prevent cramps, however.
It's important that a person doesn't drink large amounts of tonic water, which might supply a dangerous dose of quinine. If cramps aren't relieved by a normal quantity of tonic water or by the commonly recommended treatments mentioned below, a doctor should be seen.
Other Treatments for Leg Cramps
Other treatments may help leg cramps. Stretching the legs, massaging the leg muscles, applying cold compresses or hot pads to the cramped area, or taking hot baths may relieve the pain.
Increasing the intake of nutrients such as potassium, calcium, magnesium, and vitamin B complex may also help leg cramps. Drinking enough fluids may be beneficial, too. Some people report that a sports drink containing a high level of minerals is helpful.
When I wrote the first edition of this article I had never experienced a nighttime leg cramp. Since then I've experienced nocturnal cramps in a calf muscle and in a foot. They are definitely painful events! I haven't suffered from any more cramps since I've started taking a daily mutivitamin/multimineral supplement. I don't know for certain that the cramps have stopped because of the supplement, though.
If you plan on taking a daily vitamin and mineral supplement, you should do some research about the best type to take. A woman's need for iron decreases after menopause, for example. Since excess iron can be dangerous, a supplement designed for a younger woman may not be suitable for a postmenopausal one.
Should You Take Quinine?
Doctors can still prescribe quinine, but the FDA has only approved its use for the treatment of malaria. In all other cases it believes that the risks outweigh any possible benefits. If your doctor suggests that you take the medication, you should ask for detailed information about the benefits and dangers of taking the drug for your health problem.
If you're considering regularly drinking tonic water to get a low dose of quinine you should also seek your doctor’s advice, especially if you're pregnant. In addition, you should check how much quinine your chosen brand of tonic water contains. Drinking a large quantity of the water could be dangerous. Cinchona bark and quinine are interesting substances and can be very useful, but they need to be treated with care.
Information about quinine safety from the NIH
Quinine facts and precautions from WHO
Risks associated with using quinine to treat nocturnal leg cramps from the FDA
Tonic water and leg cramps from Harvard Health Publishing
Managing leg cramps from WebMD
The World Malaria Report 2017 from WHO
Malaria information from the CDC (Centers for Disease Control and Prevention)
© 2010 Linda Crampton