Primaquine phosphate is 8-[(4-Amino-1-methylbutyl)amino]-6-methoxyquinoline phosphate, a synthetic compound with potent antimalarial activity.

Primaquine (also known as primaquine phosphate) is an antimalarial medicine that is available in the United States by prescription only. It is available in tablets of 15mg base (26.3mg salt). You should know that the 15mg base tablet is the same as the 26.3mg salt tablet. It is just two different ways of describing the same thing. Primaquine has three distinct uses.

It can be prescribed by itself for prevention of malaria while traveling for short trips in areas where a certain type of malaria (P. vivax) mainly occurs. It can be prescribed after returning from a trip of long duration in combination with a second medicine for preventing malaria. Finally, it can be prescribed as a part of a combination with another medicine for the treatment of malaria.



Malaria prophylaxis

Primaquine is primarily used to prevent relapse of malaria due to Plasmodium vivax and Plasmodium ovale. It eliminates hypnozoites, the dormant liver form of the parasite, after the organisms have been cleared from the bloodstream. If primaquine is not administered to patients with proven P. vivax or P. ovale infection, a very high likelihood of relapse exists for weeks or months (sometimes years). Use in combination with quinine or chloroquine each of which is very effective at clearing P. vivax from blood, improves outcomes; they appear to also potentiate the action of primaquine.

As of 2016, the US Centers for Disease Control and Prevention recommended the use of primaquine for primary prophylaxis prior to travel to areas with a high incidence of P. vivax, and for terminal prophylaxis (anti-relapse therapy) after travel.


A single dose of primaquine has rapid and potent ability to kill gametocytes (stage V) of P. falciparum and P. vivax in blood; it also kills asexual trophozoites of P. vivax in blood, but not of P. falciparum. Because of its action against gametocytes, the WHO recommends it for use in reducing transmission to control P. falciparum infections.

Pneumocystis pneumonia

Primaquine is also used in the treatment of Pneumocystis pneumonia (PCP), a fungal infection commonly occurring in people with AIDS and, more rarely, in those taking immunosuppressive drugs. To treat PCP effectively, it is usually combined with clindamycin.

Who can take primaquine?

Primaquine can be prescribed to most adults and children of all ages.

Who should not take primaquine?

Pregnant women and people with glucose-6-phosphate dehydrogenase (or G6PD) deficiency should not take primaquine.

G6PD deficiency is a genetic disorder that some people may not know they have. People who have this disorder should not take primaquine because it can make them very sick and cause death in some instances. A simple blood test should be done before you use this medicine for the first time to make sure that you do not have this disorder. Nursing mothers should also test their babies to make sure they do not have the disorder before the mother takes primaquine

How should I take primaquine?

When taking primaquine for the prevention of malaria on a short trip, both adults and children should take one dose of primaquine per day starting a day or two before traveling to the area where malaria transmission occurs. They should take one dose per day while there, and for 7 consecutive days after leaving.

When taking primaquine after returning from a trip of long duration in combination with another preventive antimalarial medicine, both adults and children should take one dose per day for 14 days. The daily dosage for adults is 30mg base per day. Note that this is 2 tablets per day. Your doctor will have calculated the correct daily dose for your child based on the child’s weight. The child’s dose should not exceed the adult dose of 30mg base per day. Always take primaquine on a full stomach.

Will primaquine interact with my other medications?

Some other drugs can interact with primaquine and cause you problems. Your doctor is responsible for evaluating the other medicines you are taking to ensure that there are no interactions between them and primaquine.

In some instances, medicines can be adjusted to minimize the interaction. You can also ask your pharmacist to check for drug interactions.

What are the potential side effects of primaquine?

The most common side effects of primaquine are nausea and stomach pain. These side effects can often be lessened by taking primaquine with food.

Persons with the genetic disorder called G6PD deficiency could experience severe jaundice, dark urine and low blood counts which is why they should not take this medicine.

All medicines may have some side effects. Minor side effects such as nausea, occasional vomiting, or diarrhea usually do not require stopping the antimalarial drug. If you cannot tolerate your antimalarial drug, see your health care provider; other antimalarial drugs are available.

What special precautions should I follow?

Before taking primaquine,

  • Tell your doctor and pharmacist if you are allergic to primaquine, any other medications, or any of the ingredients in primaquine tablets. Ask your pharmacist for a list of the ingredients.
  • tell your doctor if you are taking penicillin; cephalosporins such as cephalexin (Keflex), cefaclor, cefuroxime (Ceftin), cefdinir (Omnicef), or cefpodoxime (Vantin); levodopa (in Sinemet); medications to treat cancer;methyldopa (Aldomet); or quinidine. Your doctor will probably tell you not to take primaquine.
  • tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take.
  • tell your doctor if you have or have ever had rheumatoid arthritis, hemolytic anemia (a condition with an abnormally low number of red blood cells), lupus erythematosus (a disease that occurs when the body’s tissues are attacked by antibodies from its own immune system), methemoglobinemia (a condition with defective red blood cells that are unable to carry oxygen to the tissues in the body),nicotinamide adenine dinucleotide (NADH) deficiency (a genetic condition), glucose-6-phosphate dehydrogenase (G6PD) deficiency (a genetic condition), or if you or someone in your family has had a reaction after eating fava beans.
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  • tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking primaquine, call your doctor.

In case of emergency/overdose

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at If the victim has collapsed, had a seizure, has trouble breathing, or can’t be awakened, immediately call emergency services at 911.

Usage In Pregnancy

Safe usage of this preparation in pregnancy has not been established. Primaquine is contraindicated in pregnant women. Even if a pregnant woman is G6PD normal, the fetus may not be 


It is not known whether primaquine is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants from primaquine, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.


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