Primaquine is used with other medications to prevent and treat malaria caused by mosquito bites in countries where malaria is common. Malaria parasites can enter the body through these mosquito bites, and then live in body tissues such as red blood cells or the liver. Primaquine is used after other medications (such as chloroquine) have killed the malaria parasites living inside red blood cells. Primaquine then kills the malaria parasites living in other body tissues. This prevents the return of the infection. Both drugs are needed for a complete cure. Primaquine belongs to a class of drugs known as antimalarials.

The United States Centers for Disease Control provide updated guidelines and travel recommendations for the prevention and treatment of malaria in different parts of the world. Discuss the most recent information with your doctor before traveling to areas where malaria occurs.

This section contains uses of this drug that are not listed in the approved professional labeling for the drug but that may be prescribed by your health care professional. Use this drug for a condition that is listed in this section only if it has been so prescribed by your health care professional.

This drug may also be used for pneumocystis pneumonia (PCP) in people with AIDS.

Take this medication by mouth as directed by your doctor, usually once daily. Take with food to prevent stomach upset. Follow your doctor's directions exactly. Primaquine is usually taken for 2 weeks after you have left the malarious area. It is started during the last 1 to 2 weeks of your other malaria treatment or immediately after you have finished your other treatment. Primaquine should not be taken for more than 14 days for malaria treatment.

The dosage is based on the kind of infection you have and your response to treatment. Take this medication regularly. To help you remember, take it at the same time every day.

It is very important to keep taking this medication exactly as prescribed by your doctor. Do not take more or less of this drug than prescribed. Do not stop taking it before completing treatment, even if you feel better, unless directed to do so by your doctor. Skipping or changing your dose without approval from your doctor may cause prevention/treatment to be ineffective, cause the amount of parasite to increase, make the infection more difficult to treat (resistant), or worsen side effects.

It is important to prevent mosquito bites (such as by using appropriate insect repellents, wearing clothes that cover most of the body, remaining in air-conditioned or well-screened areas, using mosquito nets, using insect-killing spray). Buy insect repellent before traveling. The most effective insect repellents contain diethyltoluamide (DEET). Ask your doctor or pharmacist to recommend the appropriate strengths of mosquito repellent for you/your children.

No drug treatment is completely effective in preventing malaria. Get medical help right away if you develop symptoms of malaria (such as fever, chills, headache, other flu-like symptoms), especially while in the malarious area and even after completing this prescription. Quick treatment of malaria infection is needed to prevent serious, possibly fatal, outcomes.

When using primaquine phosphate for treatment of infection, tell your doctor if your condition lasts or gets worse.

Nausea, vomiting, dizziness, stomach upset, and abdominal cramps may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if you have any serious side effects, including:

• signs of serious infection (such as sore throat that doesn't go away, high fever, severe chills)
• signs of a sudden loss of red blood cells (such as severe tiredness, brown urine, pale lips/nails/skin, fast heartbeat/breathing with usual activities)
• signs of a certain blood problem (methemoglobinemia, including bluish skin/lips/nails, headache, shortness of breath, lightheadedness, weakness, confusion, chest pain, sudden pounding heartbeat)

Get medical help right away if you have any very serious side effects, including:

• fast/irregular heartbeat
• severe dizziness
• fainting

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including:

• rash
• itching/swelling (especially of the face/tongue/throat)
• severe dizziness
• trouble breathing

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Before taking primaquine, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of:

• immune system disease (such as lupus, rheumatoid arthritis)
• blood problems (such as low white blood cell counts, anemia)
• history of blood problems due to primaquine (such as hemolytic anemia, methemoglobinemia)
• personal/family history of favism
• low levels of certain blood enzymes (glucose-6-phosphate dehydrogenase-G6PD, NADH methemoglobin reductase)

Your doctor may order a blood test to see if you have any enzyme deficiency before starting primaquine.

This drug may make you dizzy. Alcohol or marijuana (cannabis) can make you more dizzy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).

Primaquine may cause a condition that affects the heart rhythm (QT prolongation). QT prolongation can rarely cause serious (rarely fatal) fast/irregular heartbeat and other symptoms (such as severe dizziness, fainting) that need medical attention right away.

The risk of QT prolongation may be increased if you have certain medical conditions or are taking other drugs that may cause QT prolongation. Before using primaquine, tell your doctor or pharmacist of all the drugs you take and if you have any of the following conditions:

• certain heart problems (heart failure, slow heartbeat, QT prolongation in the EKG)
• family history of certain heart problems (QT prolongation in the EKG, sudden cardiac death)

Low levels of potassium or magnesium in the blood may also increase your risk of QT prolongation. This risk may increase if you use certain drugs (such as diuretics/"water pills") or if you have conditions such as severe sweating, diarrhea, or vomiting. Talk to your doctor about using primaquine safely.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Older adults may be more sensitive to the side effects of this drug, especially QT prolongation (see above).

This medication must not be used during pregnancy. It may harm an unborn baby. Women of childbearing age should have a pregnancy test before starting this medication. It is important to prevent pregnancy during and after treatment with primaquine. Men and women must use reliable forms of birth control (such as condoms, birth control pills) during treatment. Men should continue to use birth control for at least 3 months after the end of treatment. Women should continue to use birth control for at least 1 menstrual cycle after the end of treatment. If you become pregnant or think you may be pregnant, tell your doctor right away. While you are pregnant, traveling to an area with malaria puts you and your infant at a much higher risk for death and other problems. The CDC recommends continuing your other malaria treatment (such as chloroquine) throughout pregnancy until delivery to prevent harm to your unborn baby (hemolytic anemia). After delivery, you may finish treatment with primaquine. Discuss the risks and benefits with your doctor.

It is unknown if this drug passes into breast milk. The doctor should test your infant for G6PD deficiency before breastfeeding. Consult your doctor before breastfeeding.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Some products that may interact with this drug include:

• penicillamine
• quinacrine
• drugs that may cause decreased blood cells (such as trimethoprim, zidovudine, pyrimethamine, azathioprine)

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call 1-800-222-1222. Canada residents can call 1-844-764-7669. Symptoms of overdose may include: extreme drowsiness, seizures, fast/irregular heartbeat.

Do not share this medication with others.

Lab and/or medical tests (such as G6PD blood test, blood cell counts) should be done before you start taking this medication and while you are taking it. Keep all medical and lab appointments. Consult your doctor for more details.

If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.