What is Plaquenil (hydroxychloroquine)?
Plaquenil or hydroxychloroquine is used to treat or prevent acute malaria from mosquito bites in endemic areas. Plaquenil belongs to the drug class antimalarials; it works by killing parasites brought in by mosquito bites while they’re still developing in the liver or red blood cells.
Plaquenil may also be used to treat auto-immune diseases such as rheumatoid arthritis and systemic lupus erythematosus. Plaquenil also belongs to the drug class disease-modifying antirheumatic drugs (DMARDs); it works by weakening immunity to control inflammation.
Plaquenil is not recommended:
- For treatment against certain malaria strains, such as those with chloroquine or hydroxychloroquine-resistant strains.
- For treatment of severe malaria conditions.
- For treatment of COVID-19 unless used as part of a clinical study.
Plaquenil may sometimes be prescribed for other uses, such as porphyria cutanea tarda.
How is Plaquenil used?
Plaquenil can be taken alone or with other medications. Plaquenil is available in tablet form.
Store Plaquenil in a tightly closed container away from direct light, heat, or moisture at room temperature.
Keep out of reach of children.
Take Plaquenil by mouth with food or milk as directed by your doctor. Ask your doctor or pharmacist for further direction if you do not understand the instruction.
Take Plaquenil as a whole tablet – do not break, chew, or crush the tablet.
Take Plaquenil for the entire prescribed duration even if you start to feel better.
Prevention of malaria
Plaquenil must be started 1-2 weeks before traveling to the affected area. Take the prescribed dose* once a week on the same day every week. Continue taking Plaquenil weekly during your travel and for the following four weeks after leaving the affected area.
Treatment of malaria
Treatment will start with one high dose* taken immediately followed by smaller doses at the 6-hour, 24-hour, and 48-hour mark.
*Pediatric patients will be prescribed doses based on their weight.
Treatment of auto-immune diseases
Take the dose as prescribed by your doctor once or twice daily. Your doctor will adjust your dose as needed.
It’s important to understand that although Plaquenil is FDA approved, it comes with side effects that may or may not affect you.
Before starting Plaquenil, you should discuss possible side effects with your doctor or pharmacist.
Common Side Effects
Not all side effects require medical attention. As your body adjusts to Plaquenil, side effects may go away.
Tell your doctor if you experience the following symptoms, and they become severe or do not go away on their own:
- Rash, itching
- Vomiting, nausea
- Weight loss
- Dizziness, headaches
- Loss of appetite
- Abdominal pain
- Hair loss or thinning
- Severe sunburn
Serious Side Effects
Severe adverse reactions while taking Plaquenil are not common but can occur. Seek emergency medical care or call 911 if you experience any of the following symptoms:
- Allergic reaction: difficulty breathing, hives, swelling in your throat or face
- Severe skin reaction: sore throat, fever, painful skin, burning eyes, blistering rash, and peeling
- Heart problem: shortness of breath, fluttering in your chest, sudden dizziness, and fast or pounding heartbeats
Call your doctor urgently if you experience any of the following symptoms:
- Sensitivity to light
- Seeing flashing lights or halos around lights
- Changes to vision; blurry, hazy, cloudy, distorted
- Changes to eye color
- Trouble focusing or reading
- Severe muscle weakness
- Ringing in ears or trouble hearing
- Decrease or loss of consciousness
- Irregular heartbeat
- Irregular or unusual bleeding and bruising
- Anxiety, depression, or suicidal thoughts
The information above does not list all possible side effects. Contact your doctor or pharmacist if you experience any side effects not listed. You or your doctor may report side effects to the FDA by calling 1-800-FDA-1088.
Warnings & Precautions
Before taking Plaquenil, tell your doctor or pharmacist:
- If you are allergic to any medications. You should not use Plaquenil if you are allergic to chloroquine, hydroxychloroquine, quinine, or primaquine.
- If you excessively use alcohol. Using alcohol while on Plaquenil may increase your risk for liver problems.
- If you plan to become pregnant, are pregnant, or are breastfeeding.
- If you have psoriasis. Plaquenil may trigger a severe case of psoriasis.
- If you have porphyria. Plaquenil may worsen porphyria.
- Your medical history, especially if you have had diabetes, heart problems, kidney problems, or vision problems.
Plaquenil can be quickly absorbed into the body. In cases of accidental overdose, symptoms can appear within 30 minutes. If overdose is suspected, seek immediate medical attention. An overdose will be treated based on symptoms.
Overdosed symptoms include drowsiness, visual changes, headaches, cardiovascular failure, cardiac arrest, torsades de pointes, convulsions, QT prolongation, hypokalemia, ventricular tachycardia, and ventricular fibrillation.
Plaquenil can pass into breast milk. Since there are no consistent studies, Plaquenil may or may not pose a risk to your child. Consult with your doctor to determine whether you should take Plaquenil while breastfeeding.
Plaquenil may lower your blood sugar resulting in hypoglycemia which can be life-threatening. Low blood sugar must be treated immediately upon onset. If you have diabetes, you will need to monitor and measure your glucose level as directed by your doctor.
Consult with your doctor to understand the signs and symptoms of low blood sugar, such as hunger, sweating, headache, irritability, dizziness and feeling shaky or anxious, or an increased heart rate.
If you develop any signs or symptoms of hypoglycemia, contact your doctor right away or seek medical attention.
Using Plaquenil long-term or in high doses may lead to permanent vision problems by producing irreversible damage to the layer that lines the back of your eye called a retina. This risk is increased for those who have existing eye conditions, kidney disease or take tamoxifen.
Plaquenil should be stored out of reach where children cannot access this medication. Children have been reported to be more sensitive to Plaquenil with fatal overdoses, even in small amounts.
Plaquenil is recommended to treat malaria in pregnant women. Malaria during pregnancy can cause severe adverse outcomes such as premature labor and stillborn.
However, studies have shown that taking Plaquenil while pregnant may pass through to the fetus. Plaquenil should be taken only if the benefits outweigh the risk to the fetus.
Consult with your doctor to evaluate the benefits and risks of taking Plaquenil while pregnant or if you intend to be pregnant while taking Plaquenil.
Plaquenil may cause QT prolongation, a condition where the heart takes longer than usual to contract and relax. Your risk increases if you:
- Are taking other medications known to cause QT prolongation.
- Have specific existing heart problems or have a family history of heart problems.
- Have low levels of magnesium or potassium in your blood.
- Are taking diuretics or water pills.
- Have conditions with diarrhea, severe sweating, or vomiting.
Severe Skin Reactions
Severe skin reactions such as toxic epidermal necrolysis can occur when using Plaquenil.
Consult with your doctor immediately if you experience a combination of tarry black stools, diarrhea, painful urination, severe skin rash or acne, mouth ulcers or lesions, peeling or blistering skin, skin lesions or loosening, unusual bruising, or unusual weakness or drowsiness.
Plaquenil may increase your sensitivity to the sun resulting in more sunburns or skin blisters than usual. Use sunscreen often and limit your time outdoors.
Interactions & Contraindications
Before taking Plaquenil, tell your doctor or pharmacist if you take any medications, herbal supplements, or vitamins. Plaquenil (hydroxychloroquine) can interact with many medications.
Studies have shown chloroquine may significantly reduce the bioavailability of ampicillin. Ampicillin must be taken at least 2 hours before or after taking Plaquenil.
Antacids And Kaolin
Studies have shown antacids and kaolin may decrease the effect of chloroquine. Antacids must be taken 4 hours before or after taking Plaquenil.
Studies have shown antiepileptic drugs may be ineffective while using Plaquenil.
Taking Plaquenil while using cimetidine interferes with chloroquine resulting in an increased level of chloroquine in the blood. Plaquenil and cimetidine should not be taken together.
Cyclosporine plasma levels may be elevated when taking Plaquenil while using cyclosporin. Cyclosporine plasma levels must be monitored when receiving dual therapy.
Diabetic Medications and Insulins
Taking Plaquenil may result in increased efficiency of diabetic medications and insulins. Dosages for diabetic medication and insulins may need to be adjusted.
Serum digoxin levels may be elevated when taking Plaquenil while using digoxin. Serum digoxin levels must be monitored when receiving dual therapy.
Mefloquine and Other Antimalarial Medications
The risk of convulsions may increase when taking Plaquenil with other antimalarial medications such as mefloquine.
The frequency of adverse effects may increase when taking Plaquenil with methotrexate.
Taking Plaquenil while using praziquantel may significantly reduce the bioavailability of praziquantel.
The information above does not list all possible interactions and contraindications. Contact your doctor or pharmacist if you experience any interactions not listed.
Frequently Asked Questions