Take this medication by mouth, usually with food to prevent stomach upset, exactly as directed by your doctor. The dosage and length of treatment are based on your medical condition and response to treatment. Children's dosage is also based on weight.

To prevent malaria, take chloroquine as directed by your doctor, usually once a week on the same day each week. Mark a calendar to help you remember. This drug is usually started 1 to 2 weeks before entering the malarious area. Continue to take it weekly while in the area and for 4 to 8 weeks after leaving the area, or as directed by your doctor.

To treat malaria or an ameba infection, follow your doctor's instructions.

If you are also taking a certain drug for diarrhea (kaolin) or taking antacids (such as magnesium/aluminum hydroxide), take chloroquine at least 4 hours before or after these products. These products may bind with chloroquine, preventing your body from fully absorbing it.

Use this medication regularly in order to get the most benefit from it. Take this medication exactly as prescribed. Do not stop taking it without talking with your doctor. It is important to keep taking this for the length of time prescribed. Stopping prevention or treatment too soon may lead to infection or a return of the infection.

Tell your doctor if your condition lasts or gets worse. Chloroquine may not prevent malaria in all cases. If you experience fever or other symptoms of illness, get medical help right away (especially while in the malarious area and for 2 months after returning from the area). You may need a different medication. Avoid exposure to mosquitoes. (See also Notes section.)