Hydroxychloroquine is used to treat malaria. It is also used to prevent malaria infection in areas or regions where it is known that other medicines (eg, chloroquine) may not work.

Hydroxychloroquine 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, this medicine is not used to treat severe or complicated malaria.

Hydroxychloroquine is used to treat discoid lupus erythematosus (DLE) or systemic lupus erythematosus (SLE or lupus). It is also used to treat acute and chronic rheumatoid arthritis.

This medicine is available only with your doctor's prescription.

Take this medicine only 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.

Swallow the tablet whole. Do not crush, break, or chew it. Take this medicine with meals or milk to lessen stomach upset, unless otherwise directed by your doctor.

Keep using this medicine for the full treatment time, even if you feel better after the first few doses. Your infection may not clear up if you stop using the medicine too soon.

For patients taking hydroxychloroquine to prevent malaria:

Your doctor may want you to start taking this medicine 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 this medicine.
Also, you should keep taking this medicine while you are in the area and for 4 to 6 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 this medicine 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 also taking kaolin or antacids, take them at least 4 hours before or after using hydroxychloroquine.

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

Blistering, peeling, loosening of the skin

blurred vision or other vision changes

chest discomfort, pain, or tightness

cough or hoarseness

dark urine

decreased urination

defective color vision

diarrhea

difficulty breathing

difficulty seeing at night

dizziness or fainting

fast, pounding, uneven 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

fever with or without chills

general feeling of tiredness or weakness

headache

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, and sex organs

loss of hearing

lower back or side pain

noisy breathing

painful or difficult urination

red irritated eyes

red skin lesions, often with a purple center

severe mood or mental changes

sore throat sores, ulcers, or white spots on the lips or in the mouth

sticking out of the tongue

stomach pain

swelling of the feet or lower legs

swollen or painful glands

trouble with breathing, speaking, or swallowing

uncontrolled twisting movements of the neck, trunk, arms, or legs

unusual behavior

unusual bleeding or bruising

unusual facial expressions

unusual tiredness or weakness

yellow eyes or skin

Symptoms of overdose

Drowsiness

dry mouth

increased thirst

loss of appetite

mood changes

no pulse or blood pressure

numbness or tingling in the hands, feet, or lips

unconsciousness

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

Continuing ringing or buzzing or other unexplained noise in the ears

feeling of constant movement of self or surroundings

irritability

nausea

nervousness

nightmares

sensation of spinning

shakiness and unsteady walk

uncontrolled eye movements

unsteadiness, trembling, or other problems with muscle control or coordination

vomiting

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.

It is very important that your doctor check your progress at regular visits to make sure that this medicine is working properly. Blood tests may be needed to check for unwanted effects.

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).

Contact your doctor right away if you have any changes to your heart rhythm. You might feel dizzy or faint, or you might have a fast, pounding, or uneven heartbeat. Make sure your doctor knows if you had a heart rhythm problem such as QT prolongation.

This medicine may cause muscle and nerve problems. Check with your doctor right away if you have muscle weakness, pain, or tenderness while using this medicine.

Hydroxychloroquine may cause some people to be agitated, irritable, or display other abnormal behaviors. It may also cause some people to have suicidal thoughts and tendencies, or to become more depressed. If you or your caregiver notice any of these side effects, tell your doctor right away.

This medicine may cause hypoglycemia (low blood sugar). This is more common when this medicine is taken together with certain medicines. 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.

Hydroxychloroquine can temporarily lower the number of white blood cells in your blood, increasing the chance of getting an infection. If you can, avoid people with infections. Check with your doctor immediately if you think you are getting an infection or if you get a fever, chills, cough or hoarseness, lower back or side pain, or painful or difficult urination.

Serious skin reactions can occur during treatment with this medicine. Check with your doctor right away if you or your child have any of the following symptoms while using this medicine: blistering, peeling, or loose skin, red skin lesions, severe acne or skin rash, sores or ulcers on the skin, or fever or chills while you are using this medicine.

If your symptoms do not improve within a few days (or a few weeks or months for arthritis), or if they become worse, check with your doctor.

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 repellant, 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 netting 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.