Primaquine or Primaquine Phosphate. One of the uses for primaquine is to treat malaria. Another use is to treat Pneumocystis jiroveci pneumonia (PCP) which usually affects people with AIDS. To treat PCP effectively it is combined with clindamycin with adverse effects such as nausea, vomiting, and stomach cramps. Other known adverse effects that occasionally occur are anemia, headache, visual disturbance and intense itching.

It must not be administered to anyone with a G6PD deficiency as there can be a severe reaction.

Primaquine is also used to treat the P. Vivax or Ovale variants of malaria. Once the parasite has been eliminated from the bloodstream, the remaining schizont must be removed from the liver and this is done by administering a 14 day course of Primaquine. Primaquine may be administered in combination with drugs targeting the malarial parasite in the blood as it only affects the parasite in tissue and not in the blood stream.