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Aralen Phosphate

Generic name: chloroquineKLOR-oh-kwin ]
Drug classes: Amebicides, Antimalarial quinolines

Medically reviewed by on Aug 3, 2023. Written by Cerner Multum.

What is Aralen Phosphate?

Aralen Phosphate is used to treat or prevent malaria, a disease caused by parasites that enter the body through the bite of a mosquito. This medicine is not effective against all strains of malaria, or against malaria in areas where the infection has been resistant to a similar drug called hydroxychloroquine.

Aralen Phosphate is also used to treat amebiasis (infection caused by amoebae).

Aralen Phosphate may also be used for purposes not listed in this medication guide.

Aralen Phosphate side effects

Get emergency medical help if you have signs of an allergic reaction (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Also seek emergency medical attention if you have symptoms of a serious heart problem: fast or pounding heartbeats, fluttering in your chest, shortness of breath, and sudden dizziness (like you might pass out).

Aralen Phosphate may cause serious side effects. Call your doctor at once if you have:

  • a seizure;

  • ringing in your ears, trouble hearing;

  • severe muscle weakness, loss of coordination, underactive reflexes;

  • low blood cell counts--fever, chills, tiredness, mouth sores, skin sores, easy bruising, unusual bleeding, pale skin, cold hands and feet, feeling light-headed or short of breath;

  • low blood sugar--headache, hunger, sweating, irritability, dizziness, fast heart rate, and feeling anxious or shaky; or

  • a serious drug reaction that can affect many parts of your body--skin rash, fever, swollen glands, muscle aches, severe weakness, unusual bruising, or yellowing of your skin or eyes.

Taking Aralen Phosphate long-term or at high doses may cause irreversible damage to the retina of your eye. Stop taking this medicine and tell your doctor if you have:

  • blurred vision, trouble focusing, trouble reading;

  • distorted vision, poor night vision;

  • changes in your color vision;

  • hazy or cloudy vision;

  • seeing light flashes or streaks, seeing halos around lights; or

  • increased sensitivity to light.

Common side effects of Aralen Phosphate may include:

  • nausea, vomiting, diarrhea, stomach cramps;

  • headache;

  • unusual changes in mood or behavior;

  • hair loss; or

  • changes in hair or skin color.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


Aralen Phosphate can cause dangerous effects on your heart, especially if you also use certain other medicines. Seek emergency medical attention if you have fast or pounding heartbeats and sudden dizziness (like you might pass out).

Taking Aralen Phosphate long-term or at high doses may cause irreversible damage to the retina of your eye that could progress to permanent vision problems. You may not be able to use Aralen Phosphate if you have a history of vision changes or damage to your retina.

Stop taking Aralen Phosphate and call your doctor at once if you have blurred vision, trouble focusing, distorted vision, blind spots, trouble reading, hazy or cloudy vision, increased sensitivity to light.

Before taking this medicine

You should not use this medicine if you are allergic to Aralen Phosphate or hydroxychloroquine. You may not be able to use this medicine if you have ever had vision changes or damage to your retina.

High doses or long-term use of chloroquine may cause irreversible damage to your retina (the membrane layer inside your eye that helps produce vision). This could progress to permanent vision problems. The risk of retinal damage is higher in people with pre-existing eye problems, kidney disease, or people who also take tamoxifen.

Tell your doctor if you have ever had:

  • vision changes or damage to your retina caused by an anti-malaria medication;

  • heart disease, heart rhythm disorder (such as long QT syndrome);

  • an electrolyte imbalance (such as low levels of potassium or magnesium in your blood);

  • diabetes;

  • liver or kidney disease;

  • psoriasis;

  • alcoholism;

  • porphyria (a genetic enzyme disorder that causes symptoms affecting the skin or nervous system); or

  • a genetic enzyme deficiency called glucose-6-phosphate dehydrogenase (G6PD) deficiency.

Tell your doctor if you are pregnant or plan to become pregnant. Malaria is more likely to cause serious illness or death in a pregnant woman. Having malaria during pregnancy may also increase the risk of miscarriage, stillbirth, premature delivery, and low birth weight.

It is not known whether Aralen Phosphate will harm an unborn baby. If you are pregnant, ask your doctor about the risks of traveling to areas where malaria is common (such as Africa, South America, and Southern Asia).

You should not breastfeed while using Aralen Phosphate.

How should I take Aralen Phosphate?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

To prevent malaria: Aralen Phosphate is usually taken once per week on the same day each week. Start taking the medicine 2 weeks before entering an area where malaria is common. Keep taking the medicine during your stay and for at least 8 weeks after you leave the area.

To treat malaria: Aralen Phosphate is usually given as one high dose followed by smaller doses during the next 2 days in a row.

To treat amebiasis: Aralen Phosphate is given in a high starting dose for 2 days followed by a smaller dose for 2 to 3 weeks. You may be given other medications to help prevent further infection.

Aralen Phosphate doses are based on weight in children. Your child's dose needs may change if the child gains or loses weight.

Use Aralen Phosphate for the full prescribed length of time, even if your symptoms quickly improve.

Call your doctor as soon as possible if you have been exposed to malaria, or if you have fever or other symptoms of illness during or after a stay in an area where malaria is common.

Use protective clothing, insect repellents, and mosquito netting around your bed to further prevent mosquito bites that could cause malaria.

No medication is 100% effective in treating or preventing all types of malaria. Talk with your doctor if you have fever, vomiting, or diarrhea during your treatment.

While using Aralen Phosphate, you may need frequent medical tests and vision exams.

Store at room temperature away from moisture, heat, and light.

What happens if I miss a dose?

Call your doctor for instructions if you miss a dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. An overdose of Aralen Phosphate can be fatal, and must be treated quickly.

Overdose symptoms may include drowsiness, vision changes, seizure, slow heart rate, weak pulse, pounding heartbeats, sudden dizziness, fainting, shortness of breath, or slow breathing (breathing may stop).

Keep Aralen Phosphate out of the reach of children. A Aralen Phosphate overdose can be fatal to a child who accidentally swallows this medicine.

What should I avoid while taking chloroquine?

This medicine may cause blurred vision and may impair your reactions. Avoid driving or hazardous activity until you know how this medicine will affect you.

Avoid taking an antacid or Kaopectate (kaolin-pectin) within 4 hours before or 4 hours after you take Aralen Phosphate.

What other drugs will affect Aralen Phosphate?

Aralen Phosphate can cause a serious heart problem. Your risk may be higher if you also use certain other medicines for infections, asthma, heart problems, high blood pressure, depression, mental illness, cancer, malaria, or HIV.

If you take an antibiotic called ampicillin, take it 2 hours before or 2 hours after you take your Aralen Phosphate dose.

Tell your doctor about all your other medicines, especially:

This list is not complete. Other drugs may affect Aralen Phosphate, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

Popular FAQ

Multiple public health organizations, including the FDA, NIH and WHO have halted emergency use or study of hydroxychloroquine for COVID-19. Continue reading

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.