Quinine is a drug that treats malaria, according to Mayo Clinic. Quinine works by destroying or inhibiting the growth of the malaria-causing parasite Plasmodium falciparum, which enters the body through mosquito bites, states WebMD.
This medication is only available with a doctor's prescription, notes Mayo Clinic. Side effects associated with quinine include mild headache, dizziness, sweating, blurred vision and ringing in the ears. Another side effect is low blood sugar, or hypoglycemia, states WebMD.
The patient should consult a doctor when these side effects worsen during treatment or persist after treatment, advises WebMD. Allergic reactions such as itching, rashes, swelling, trouble breathing and acute dizziness are rare but serious.