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The Effects of Quinine Hydrochloride

By Saad Mohammad ; Updated August 14, 2017

Quinine is a drug that is primarily used for the treatment of malaria and is found naturally in the bark of the cinchona tree. Its exact method of action is not well understood, but it seems to accumulate in the red blood cells that have been infected with malaria and as a result destroys the parasites. It cannot cure malaria, as it has no effect on the parasitic form that exists outside of the red blood cell. It has many adverse side effects, which must be understood by the patient before beginning a course of treatment with the medication.


Chichonism is a cluster of symptoms, and it occurs in almost all the patients using quinine. The mild form consists of a headache, sweating, nausea and vomiting, tinnitus (ringing in the ears), vasodilation peripherally (manifests as skin that is warm and red), visual disturbances (altered color perception and blurriness) and dizziness. With higher doses, severe effects such as diarrhea, loss of hearing and vision, abdominal pain and cardiac arrhythmia can become evident. Severe symptoms can necessitate discontinuation of the medication.

Visual Effects

Quinine has effects on the optic nerve and the retina of the eye, with many symptoms possible as a result. They include loss of vision, altered color perception, photophobia, fixed dilation of the pupils, night blindness and blurry sight. Stopping drug administration will generally resolve symptoms.


Itchiness and flushing of the skin are common results of hypersensitivity to quinine. Rash, fever, urticaria (hives) and wheezing also occur especially in asthmatics, and this warrants close follow-up of the patient. Other severe complications such as Steven-Johnson and erythema multiforme syndrome have also been reported Hypersensitivity reactions in general warrant cessation of quinine treatment.

Hematologic Effects

Quinine has adverse effects on components of the blood as well. Agranulocytosis is one, which refers to a serious decrease in white blood cells, especially neutrophils. Bleeding or bruising that is unusual can hint towards thrombocytopenia, which is a severe reduction in the number of platelet cells and can be life threatening. Disseminated intravascular coagulation (DIC) is also a feared consequence, which basically is a massive amount of clotting occurring within the blood vessels of the body, often manifests as unexplained drop in platelets and kidney failure. Hematologic effects usually resolve with discontinuation of quinine.

Endocrine Effects

Quinine can have effects on the secretion of insulin by the pancreas, and as a result, hypoglycemia often results. Patients at increased risk of this complication are children, pregnant women and those with more severe malarial infections.

Cardiovascular Effects

Normal dosage of quinine has not been reported to cause serious side effects in those without preexisting cardiac problems. Hypotension (low blood pressure), prolongation of the QT segment on the EKG, various arrhythmia (ventricular fibrillation and bradycardia), chest pain and even cardiac arrest have been noted.

Other Effects

Pulmonary effects such as difficulty breathing and asthma have been reported with quinine use. Kidneys have also been reported to suffer from nephritis, kidney failure and overall impairment of function. Liver compromise is also possible with jaundice, hepatitis, and abnormal liver function tests being reported as well. In addition, myalgia (muscle pain) has been seen with quinine treatment.

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