Quinine: The Potentially Lethal Ingredient in Your Gin and Tonic

By Paul Gaita 01/10/17

New research is highlighting the dangers of the rare but serious illness.

a gin and tonic with lime.

Quinine is an alkaloid derived from the bark of the cinchona tree, and has been used for centuries as a treatment for malaria. When administered in tonic water to British troops in India during the 1700s, its bitter taste was cut with gin, which gave rise to the gin and tonic.

Though no longer a primary treatment for malaria, quinine remains a popular beverage ingredient, both in gin and tonics and in bitter lemon or lime drinks. 

As with any chemical, quinine has its side effects, from stomach distress to fever and hypotension, which was enough for the Food and Drug Administration to ban its use for nighttime leg cramps.

Now, a new research article published in the New England Journal of Medicine highlights a rare but serious and potentially deadly reaction to quinine: an allergy to the chemical that can cause thrombocytopenia, a drop in the blood's platelet count that can cause internal and external bleeding and even kidney failure.

The article cites a case overseen by one of its authors, Dr. James N. George, a hematologist and professor at the University of Oklahoma Health Sciences Center, in 2009. Upon returning from an office party, an otherwise healthy 35-year-old woman began experiencing chills, nausea and stomach cramps that quickly elevated to explosive vomiting and diarrhea.

Emergency room doctors found that her blood counts were unusual—high white cell count and low platelets—but treated her for a stomach virus. Two days later, the woman was back in the emergency room, now experiencing an array of serious problems, from kidney failure to abnormal liver function and anemia. Blood clots throughout her body were found to be blocking her blood flow and causing the organ failure.

Doctors placed her on dialysis and began a procedure to replace her blood plasma when Dr. George was called in. Believing her condition to be an allergic reaction, he began asking the patient about various foods or medications that might cause such results. He finally struck upon the idea that quinine might be the cause, and indeed, the woman had consumed a drink at the office party that contained vodka and tonic. She had, in fact, experienced a similar reaction to a vodka and tonic one year earlier. Blood tests soon confirmed the patient's allergy to quinine.

In the article, George and his co-authors note that medical literature cites 112 definite cases of allergic reaction to quinine, and in three cases, fatalities caused by ingesting the substance. The reaction is the result of antibodies in the individuals with the allergy that treat the cells that line their blood vessels as infection and react against them. In most cases, the effect is minimal, but when the quinine molecule is introduced to the body, the antibodies are altered to such a degree that damage to the blood vessels becomes catastrophic. Organs like the kidney are likely targets, as was the case with the patient in the study.

Currently, there appears to be no way to determine if an individual is susceptible to quinine allergy—save from experiencing the reaction—and there is no clear-cut treatment. In the case of the patient cited in Dr. George's study, blood plasma exchange returned her to only partial health; she still suffers from migraines and reduced kidney function, as well as some mild cognitive impairment.

The condition, however, remains exceptionally rare, so individuals who have been drinking beverages with quinine and have not experienced a reaction should not be concerned about possible future problems.

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Paul Gaita lives in Los Angeles. He has contributed to the Los Angeles Times, Variety, LA Weekly, Amazon.com and The Los Angeles Beat, among many other publications and websites.