Primaquine: a practical guide for stopping malaria relapses
Ever heard of a drug that targets the hidden part of malaria? That’s primaquine. It’s not for everyday fevers — it targets liver stages of certain malaria types and helps prevent future attacks. If you travel to places where Plasmodium vivax or P. ovale are common, primaquine is often part of the plan.
How primaquine works and when it’s used
Primaquine kills the dormant liver forms (hypnozoites) that cause relapses weeks or months after the first infection. Doctors call this a "radical cure." It also helps reduce spread of P. falciparum by cutting the parasite’s ability to infect mosquitoes when given as a low single dose.
Typical uses you’ll see: after an infection with P. vivax or P. ovale to prevent relapse, or as a single low dose to reduce transmission of P. falciparum in certain public-health settings. It’s not a substitute for standard blood-stage treatment — it’s added to stop the liver from hiding parasites.
Safety: the one big test you must know about
The most important safety issue is G6PD deficiency. If you have low G6PD enzyme activity, primaquine can trigger severe hemolytic anemia — that means your red blood cells break down fast. That can cause dark urine, yellow skin or eyes, extreme tiredness, and shortness of breath. Get a G6PD test before taking primaquine when possible.
Other side effects are usually mild: stomach upset, nausea, and rarely methemoglobinemia (which can make you feel breathless or bluish). Pregnant people should avoid primaquine because the baby’s G6PD status is unknown. Breastfeeding mothers need a doctor’s advice — newborns are vulnerable to hemolysis.
Dosage notes: a common adult radical cure is 15 mg daily for 14 days. For blocking P. falciparum transmission, the World Health Organization supports a single low dose (0.25 mg/kg) in many settings. Your doctor may adjust doses based on local guidelines and weight. Never self-prescribe.
What to watch for: stop the drug and seek care if you notice dark-colored urine, sudden weakness, fainting, or rapid heart rate. If you’re traveling, carry a copy of your G6PD test and a clear plan from your clinician on what to do if symptoms appear.
Bottom line: primaquine is powerful for preventing relapse and limiting transmission, but it comes with a real safety check — know your G6PD status and follow medical advice. Ask your travel clinic or doctor about testing and the right regimen for your trip or treatment.
