Generic Name: chloroquine (KLOR-oh-kwin)
Medically reviewed by Drugs.com. Last updated on July 18, 2020.
Commonly used brand name(s)
In the U.S.
- Aralen Phosphate
Available Dosage Forms:
Therapeutic Class: Antimalarial
Chemical Class: Aminoquinoline
Uses for chloroquine
Chloroquine is used to prevent and treat malaria. It is also used to treat liver infection caused by protozoa (extraintestinal amebiasis). Chloroquine may also be used to treat coronavirus (COVID-19) in certain hospitalized patients.
Using chloroquine alone or with other medicines (eg, azithromycin) may increase your risk of heart rhythm problems (eg, QT prolongation, ventricular fibrillation, ventricular tachycardia). Chloroquine should only be used for COVID-19 in a hospital or during clinical trials. Do not take any medicine that contains chloroquine unless prescribed by your doctor.
Chloroquine belongs to a group of medicines known as antimalarials. It works by preventing or treating malaria, a red blood cell infection transmitted by the bite of a mosquito. However, chloroquine is not used to treat severe or complicated malaria and to prevent malaria in areas or regions where chloroquine is known not to work (resistance).
Chloroquine is available only with your doctor's prescription.
Before using chloroquine
In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For chloroquine, the following should be considered:
Tell your doctor if you have ever had any unusual or allergic reaction to chloroquine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.
Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of chloroquine to prevent and treat malaria in children. However, children are more sensitive to the effects of chloroquine than adults. Safety and efficacy of chloroquine to treat extraintestinal amebiasis have not been established in children.
Although appropriate studies on the relationship of age to the effects of chloroquine have not been performed in the geriatric population, geriatric-specific problems are not expected to limit the usefulness of chloroquine in the elderly. However, elderly patients are more likely to have age-related kidney problems, which may require caution and an adjustment in the dose for patients receiving chloroquine.
There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.
Interactions with medicines
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking chloroquine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using chloroquine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.
Using chloroquine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Agalsidase Alfa
- Aripiprazole Lauroxil
- Arsenic Trioxide
- Chloral Hydrate
- Inotuzumab Ozogamicin
- Insulin Aspart, Recombinant
- Insulin Bovine
- Insulin Degludec
- Insulin Detemir
- Insulin Glulisine
- Insulin Lispro, Recombinant
- Rabies Vaccine
- Sodium Phosphate
- Sodium Phosphate, Dibasic
- Sodium Phosphate, Monobasic
Using chloroquine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Aluminum Carbonate, Basic
- Aluminum Hydroxide
- Aluminum Phosphate
- Calcium Carbonate
- Dihydroxyaluminum Aminoacetate
- Dihydroxyaluminum Sodium Carbonate
- Magnesium Carbonate
- Magnesium Hydroxide
- Magnesium Oxide
- Magnesium Trisilicate
- Sodium Bicarbonate
Interactions with food/tobacco/alcohol
Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.
Other medical problems
The presence of other medical problems may affect the use of chloroquine. Make sure you tell your doctor if you have any other medical problems, especially:
- Allergy to 4-aminoquinoline compounds (eg, hydroxychloroquine) or
- Eye or vision problems (eg, retinal or visual field changes) caused by 4-aminoquinoline compounds—Should not be used in patients with these conditions.
- Blood or bone marrow problems or
- Eye or vision problems (eg, macular degeneration, retinopathy) or
- Hearing problems or
- Muscle weakness or
- Porphyria (blood disorder) or
- Psoriasis (skin disease) or
- Stomach or bowel problems—Use with caution. May make these conditions worse.
- Bradycardia (slow heartbeat) or
- Heart disease or
- Heart rhythm problems, or history of or
- Hypokalemia (low potassium in the blood), uncorrected or
- Hypomagnesemia (low magnesium in the blood), uncorrected—Use with caution. May prolong the QT interval.
- Epilepsy, history of—May increase risk for seizures.
- Glucose-6-phosphate dehydrogenase (G6PD) deficiency—May cause hemolytic anemia in patients with this condition.
- Kidney disease or
- Liver disease—Use with caution. The effects may be increased because of the slower removal of chloroquine from the body.
Proper use of chloroquine
Take chloroquine exactly as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered. To do so may increase the chance of serious side effects.
For patients taking chloroquine to prevent malaria:
- Your doctor will want you to start taking chloroquine 1 to 2 weeks before you travel to an area where there is a chance of getting malaria. This will help you to see how you react to the medicine. Also, it will allow time for your doctor to change to another medicine if you have a reaction to chloroquine.
- Also, you should keep taking chloroquine while you are in the area and for 4 weeks after you leave the area. No medicine will protect you completely from malaria. However, to protect you as completely as possible, it is important to keep taking chloroquine for the full time your doctor ordered. Also, if fever develops during your travels or within 2 months after you leave the area, check with your doctor immediately.
If you are taking chloroquine to help keep you from getting malaria, keep taking it for the full time of treatment. If you already have malaria, you should still keep taking chloroquine for the full time of treatment even if you begin to feel better after a few days. This will help clear up your infection completely. If you stop taking chloroquine too soon, your symptoms may return.
Chloroquine works best when you take it on a regular schedule. For example, if you are taking it once a week to prevent malaria, it is best to take it on the same day of each week. Make sure that you do not miss any doses. If you have any questions about this, check with your doctor.
If you are also taking kaolin or antacids, take them at least 4 hours before or after using chloroquine. If you are also taking ampicillin, take it at least 2 hours before or after using chloroquine.
The dose of chloroquine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of chloroquine. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
- For oral dosage form (tablets):
- For prevention of malaria:
- Adults—500 milligrams (mg) once a week on the same day of each week starting 2 weeks before traveling to an area where malaria occurs, and continued for 8 weeks after leaving the area.
- Children—Dose is based on body weight and must be determined by your doctor. The dose is usually 5 milligram (mg) per kilogram (kg) of body weight once per week on the same day each week starting 2 weeks before traveling to an area where malaria occurs, and continued for 8 weeks after leaving the area.
- For treatment of malaria:
- Adults—At first, 1000 milligrams (mg) once a day. Then, 500 mg 6 to 8 hours after the first dose, and 500 mg on the second and third days of treatment.
- Adults with low body weight and children—Dose is based on body weight and must be determined by your doctor. At first, 10 milligram (mg) per kilogram (kg) of body weight. Then, 5 mg per kg of body weight taken 6 hours, 24 hours, and 36 hours after the first dose.
- For treatment of liver infection caused by protozoa:
- Adults—1000 milligrams (mg) once a day, taken for 2 days. This is followed by 500 mg once a day for at least 2 to 3 weeks.
- Children—Use and dose must be determined by your doctor.
- For prevention of malaria:
If you miss a dose of chloroquine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Ask your healthcare professional how you should dispose of any medicine you do not use.
Precautions while using chloroquine
If you will be taking chloroquine for a long time, it is very important that your doctor check your progress at regular visits. This is to make sure that the infection is cleared up completely, and to allow your doctor to check for any unwanted effects. Your doctor may check your blood, urine, eyes, ears, and knee or ankle reflexes during or after using chloroquine.
If your symptoms do not improve within a few days, or if they become worse, check with your doctor.
Chloroquine may cause heart problems and changes in your heart rhythm. Check with your doctor right away if you have chest pain or tightness, decreased urine output, dilated neck veins, extreme fatigue, swelling of the face, fingers, feet, or lower legs, troubled breathing, or weight gain. You may also feel dizzy or faint, or you may have a fast, pounding, or uneven heartbeat.
Chloroquine may cause hypoglycemia (low blood sugar), which may be life-threatening. Low blood sugar must be treated before it causes you to pass out (unconsciousness). People feel different symptoms of low blood sugar. It is important that you learn which symptoms you usually have so you can treat it quickly. Talk to your doctor about the best way to treat low blood sugar.
Chloroquine may cause vision problems. It may also make you dizzy or lightheaded. Do not drive or do anything else that could be dangerous until you know how chloroquine affects you. . If these reactions are especially bothersome, check with your doctor.
Check with your doctor immediately if blurred vision, difficulty with reading, or any other change in vision occurs during or after treatment. Your doctor may want your eyes be checked by an ophthalmologist (eye doctor).
Chloroquine may cause extrapyramidal disorders (eg, dystonia, dyskinesia, tongue protrusion, torticollis). Check with your doctor right away if you have the following symptoms after using the medicine: difficulty in speaking, drooling, loss of balance control, muscle trembling, jerking, or stiffness, restlessness, shuffling walk, stiffness of the limbs, twisting movements of the body, or uncontrolled movements, especially of the face, neck, and back.
Using chloroquine for a long time may cause muscle weakness. Check with your doctor right away if you have muscle weakness while using chloroquine.
Children are very sensitive to chloroquine, and accidental overdoses have occurred with small amounts of chloroquine. Keep chloroquine out of the reach of children.
Check with your doctor right away if you have continuing ringing or buzzing or other unexplained noise in the ears or hearing loss while using chloroquine.
While you are being treated with chloroquine, do not have any immunizations (eg, rabies vaccine) without your doctor's approval.
Malaria is spread by the bites of certain kinds of infected female mosquitoes. If you are living in or will be traveling to an area where there is a chance of getting malaria, the following mosquito-control measures will help to prevent infection:
- If possible, avoid going out between dusk and dawn because it is at these times that mosquitoes most commonly bite.
- Remain in air-conditioned or well-screened rooms to reduce contact with mosquitoes.
- Wear long-sleeved shirts or blouses and long trousers to protect your arms and legs, especially from dusk through dawn when mosquitoes are out.
- Apply insect repellent, preferably one containing DEET, to uncovered areas of the skin from dusk through dawn when mosquitoes are out.
- If possible, sleep in a screened or air-conditioned room or under mosquito netting, preferably coated or soaked with pyrethrum, to avoid being bitten by malaria-carrying mosquitoes.
- Use mosquito coils or sprays to kill mosquitoes in living and sleeping quarters during evening and nighttime hours.
Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.
Chloroquine side effects
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
Incidence not known
- attempts at killing oneself
- back, leg, or stomach pains
- black, tarry stools
- bleeding gums
- blistering, peeling, or loosening of the skin
- blood in the urine or stools
- blurred or decreased vision
- change in near or distance vision
- chest discomfort or pain
- cold sweats
- continuing ringing or buzzing or other unexplained noise in the ears
- dark urine
- difficulty in focusing the eyes
- difficulty with speaking
- difficulty with swallowing
- disturbed color perception
- dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
- double vision
- fast, slow, irregular, or pounding heartbeat
- feeling that others are watching you or controlling your behavior
- feeling that others can hear your thoughts
- feeling, seeing, or hearing things that are not there
- general tiredness and weakness
- halos around lights
- hearing loss
- inability to move the eyes
- increased blinking or spasms of the eyelid
- joint or muscle pain
- large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
- light-colored stools
- loss of balance control
- lower back or side pain
- muscle trembling, jerking, or stiffness
- muscular pain, tenderness, wasting, or weakness
- night blindness
- overbright appearance of lights
- painful or difficult urination
- pale skin
- pinpoint red spots on the skin
- puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
- red skin lesions, often with a purple center
- red, irritated eyes
- shuffling walk
- skin rash, hives, or itching
- sore throat
- sores, ulcers, or white spots on the lips or in the mouth
- sticking out of the tongue
- stiffness of the limbs
- swollen or painful glands
- tightness in the chest
- trouble breathing
- tunnel vision
- twitching, twisting, or uncontrolled repetitive movements of the tongue, lips, face, arms, or legs
- uncontrolled movements, especially of the face, neck, and back
- unusual bleeding or bruising
- unusual tiredness or weakness
- upper right abdominal or stomach pain
- yellow eyes and skin
Get emergency help immediately if any of the following symptoms of overdose occur:
Symptoms of overdose
- Cold, clammy skin
- decreased urine
- dry mouth
- fast, weak pulse
- increased thirst
- lightheadedness, dizziness, or fainting
- loss of appetite
- muscle pain or cramps
- numbness or tingling in the hands, feet, or lips
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
Incidence not known
- Change in hair color
- hair loss
- increased sensitivity of the skin to sunlight
- redness or other discoloration of the skin
- severe sunburn
- stomach cramps
- trouble sleeping
- weight loss
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
Frequently Asked Questions
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- Drug class: amebicides
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Other brands: Aralen Phosphate