Drug Interactions with Primaquine: What You Need to Know

When you take primaquine, an antimalarial drug used to prevent relapse of Plasmodium vivax and P. ovale malaria. Also known as an 8-aminoquinoline, it works by killing dormant liver parasites that other drugs miss. But it’s not safe for everyone—especially if you’re on other meds or have a genetic condition called G6PD deficiency. This is why understanding drug interactions with primaquine isn’t just helpful—it’s life-saving.

Primaquine doesn’t play well with certain other drugs. For example, combining it with chloroquine, a common malaria treatment can increase the risk of heart rhythm problems. It also interacts with cimetidine, a stomach acid reducer, which can raise primaquine levels in your blood and make side effects worse. And if you’re taking proguanil, another antimalarial often used in combination therapy, you might think it’s safe—but the combo can still increase your risk of blood cell damage, especially if you have G6PD deficiency. That’s the big one: if your body can’t handle oxidative stress due to low G6PD enzyme levels, primaquine can trigger severe anemia. It’s not rare—millions worldwide carry this trait, especially in Africa, Asia, and the Mediterranean.

Even over-the-counter stuff matters. Avoid dapsone, a drug used for leprosy and some skin conditions, because it can add to the risk of hemolytic anemia. Same goes for sulfonamides like sulfa antibiotics. And don’t forget about supplements—vitamin E and other antioxidants might interfere with how primaquine works. Your doctor needs to know everything you’re taking, even herbal teas or vitamins bought online. The goal isn’t to scare you—it’s to make sure you get the full benefit of primaquine without the danger.

Most of the posts on this page focus on how drugs behave with each other—whether it’s nevirapine resistance, amiloride in pregnancy, or comparing muscle relaxants. They all share the same core idea: medications don’t work in isolation. Primaquine is no different. What you’ll find here are real, practical guides that break down exactly what to watch for, who’s at risk, and how to talk to your provider about alternatives if primaquine isn’t right for you. No fluff. No guesswork. Just what you need to stay safe and get better.