June 25, 2025, 3:41 am | Read time: 4 minutes
Anyone who suffers from ringing and beeping in the ears or has visual disturbances should not drink anything with quinine, which is often contained in bitter drinks. This could make the symptoms worse. FITBOOK nutrition editor Sophie Brünke explains which other people are at risk.
A tragic case report is currently circulating from Ludwigsburg Hospital about a 25-year-old patient who unknowingly combined tonic water with a medication that caused a dangerous interaction—and led to her death. You can find out the mechanism behind this and in which other cases you should stay away from bitter soft drinks here.
Overview
Tonic Water and Loperamide — a Life-Threatening Combination
A healthy 25-year-old woman from Ludwigsburg fell ill with gastroenteritis. When her symptoms worsened in the evening, she took loperamide in consultation with the emergency medical service. As there was no improvement, she also took ibuprofen for the pain and loperamide again in the early morning. As the case report from the Clinic for Anesthesia, Intensive Care Medicine, Emergency Medicine, and Pain Therapy at Ludwigsburg Hospital explains, her partner found her unresponsive in the morning and contacted the emergency services. They diagnosed a circulatory arrest..1
What Had Happened in Her Body?
In the hospital, hypoxic brain damage was finally diagnosed. Other causes for the young woman’s brain death were ruled out. The poisoning probably occurred because she had drunk around two and a half liters of tonic water the day before. The bitter drink contains 60 to 80 milligrams of quinine per liter, depending on the variety. The bitter substance interacted with the loperamide. The quinine from the tonic water can inhibit the breakdown of loperamide in the brain and thus increase the risk of an overdose.
The case report from the hospital concludes with a recommendation that future drug packaging should include a hazard warning for quinine-containing soft drinks.
Other Cases Where Caution Is Advised
The plant substance quinine can lead to health problems in pregnant women and people with tinnitus, muscle weakness, cardiac arrhythmia, or a damaged optic nerve if they consume large quantities of the alkaloid from the cinchona tree. This information was confirmed by the Bavarian consumer advice center in response to an inquiry from the dpa.
As a precaution, those affected should avoid drinks containing quinine, such as tonic water or bitter lemon, advises consumer advocate Michelle Veith. Anyone taking medication other than loperamide, such as anticoagulants, opioids, neuroleptics, or certain antidepressants, should also be careful..2
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If in Doubt in a Restaurant, Ask
Reviewing the non-alcoholic drink options on a restaurant’s notice board or menu should make it easy to identify drinks containing quinine. According to the consumer advice center, it is mandatory for restaurants to refer to the bitter substance as “aroma quinine.” The situation is different for spirits and alcoholic mixed drinks. It is not always clear whether they contain quinine. If in doubt, it is advisable to ask or to avoid the drink in question.
Quinine Is Not Just a Component of Tonic Water and Other Drinks
Quinine is not only found in drinks such as tonic water, bitter lemon, or mixed drinks and spirits. As FITBOOK author and ecotrophologist Beke Enderstein already explained in an earlier article, quinine is also used in medicine. The plant substance has become established for the medicinal treatment of malaria. It is also prescribed as a treatment for calf cramps. Other areas of application: as a remedy for infections and flu-like infections (fever reducer) and as a painkiller.
*With material from dpa
The German original of this article was published in September 2024.