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Boxed warning

Plaquenil has US Food and Drug Administration (FDA) boxed warnings. This medication is not effective in places where malaria parasites are resistant to the earlier malaria drug chloroquine. 

Irreversible retinal damage has been observed in some patients who had used high doses of Plaquenil or used it long-term.¹

Children are exceptionally sensitive to the compounds present in Plaquenil.

A number of fatalities have been reported following the accidental ingestion of chloroquine (the drug from which Plaquenil is derived) by children, even in small doses; therefore, this drug must be kept out of the reach of children at all times.

Cases of life-threatening and fatal cardiomyopathy have been reported with the use of Plaquenil. Prolonged QT interval, ventricular arrhythmias, and tachycardia have also been reported.²

There’s evidence Plaquenil may trigger or exacerbate psoriasis symptoms in some people.³

What is Plaquenil?

Plaquenil is the brand name of the active ingredient hydroxychloroquine. It is a medication primarily used to prevent and treat malaria, a disease caused by mosquito bites. Plaquenil is also a disease-modifying anti-rheumatic drug (DMARD) that can treat autoimmune diseases like rheumatoid arthritis and lupus. Doctors sometimes prescribe Plaquenil for people with Sjogren's syndrome; however, the US FDA has not yet validated its safety and effectiveness in treating this condition. Plaquenil works by suppressing the immune system and reducing inflammation, which may help prevent joint or organ damage and serious complications from certain autoimmune conditions.

Plaquenil is available as a tablet for oral use, with a strength of 200mg. It is also available under its generic name (hydroxychloroquine).⁴

What is Plaquenil used to treat?

Your doctor may prescribe Plaquenil if you have malaria, lupus, or rheumatoid arthritis.

Plaquenil is a prescription medication that is prescribed for:

  • Preventing and treating certain types of malaria in adults and children⁵

  • Adults with chronic discoid lupus erythematosus⁶

  • Adults with systemic lupus erythematosus⁷

  • Adults with rheumatoid arthritis⁸

Dosage forms and strengths

Plaquenil tablets contain 200mg of hydroxychloroquine sulfate. The recommended dosage depends on its intended use and, in children, body weight.

How do you take Plaquenil?

How you take Plaquenil will depend on your age and which condition your doctor is treating.

Malaria prevention

If you’re traveling to an area where preventative malaria treatments are beneficial, your doctor will prescribe Plaquenil (or the generic version of the drug) to prevent malaria. You will begin treatment two weeks before traveling to a malaria-endemic area and will continue for the duration of your stay and for four weeks following your return.⁹

Adult dosage

Adults requiring protection from malaria will take a weekly dose of 400mg on the same day each week. 

Child dosage

If your child is traveling with you, they’ll also need preventative treatment for malaria. Your doctor will calculate the appropriate dose based on your child’s weight.

Malaria treatment

If you’re diagnosed with malaria, you’ll start with a higher dose of Plaquenil.¹⁰

Adult dosage

Adults being treated for malaria with Plaquenil will take a single 800mg dose as soon as they’re diagnosed, followed by another dose of 400mg six to eight hours later, and subsequent doses of the same strength once daily for the next two days.

Child dosage

If your child contracts malaria, your doctor will use your child’s weight to decide on a safe and effective dosage.

Lupus erythematosus treatment

When used to treat lupus erythematosus (systemic or discoid), 200mg to 400mg of Plaquenil is administered daily, either as a single dose or divided into two doses.¹¹

Rheumatoid arthritis treatment

People with rheumatoid arthritis will likely require a higher initial dose of Plaquenil and a lower dose for maintenance.¹¹

Initial dosage

If you have rheumatoid arthritis, your doctor will prescribe an initial treatment of 400mg to 600mg, which may be given as a single dose or split into two doses administered on the same day. 

Maintenance dosage

After the initial dose, you’ll take a daily dose of 200mg to 400mg, which may be taken as a single dose or divided into two. 

Regardless of its intended effect (treating or preventing malaria, treating lupus erythematosus, or treating rheumatoid arthritis), a Plaquenil tablet must be swallowed whole; do not split, chew, or crush the tablet. To avoid upsetting your stomach, take the medication with a glass of milk or a meal.

Take care to follow the recommendations on your prescription label carefully, and ask your doctor or pharmacist to explain any details that aren’t clear. With respect to dosage and timing, be sure to take Plaquenil precisely as prescribed by your doctor. Do not take more or less of it or take it more frequently than your doctor prescribes.

If you’re taking Plaquenil for the treatment of rheumatoid arthritis or lupus symptoms, you should see an improvement within six months. If your symptoms don’t improve, your doctor will likely recommend discontinuing the medication.

However, if you and your doctor determine that the medicine is working for you, you should continue taking it as prescribed. If you stop using Plaquenil, your symptoms will reappear.

Seeing results

Plaquenil works gradually and slowly, so it may take a long time to see improvements. If you’re taking Plaquenil for an autoimmune condition (lupus erythematosus or rheumatoid arthritis), you may start noticing improvements in as little as one to three months, and your symptoms may continue to improve for up to a year after starting Plaquenil alongside other pain and stiffness medicines.

Who should not take Plaquenil?

Plaquenil is contraindicated in anyone with a history of hypersensitivity to 4-aminoquinoline compounds.¹¹

Plaquenil is not suitable for people who have experienced vision problems, blood or bone marrow problems, skeletal issues, neurological problems, glucose-6-phosphate dehydrogenase (G6PD) deficiency, hypoglycemia, liver problems, or renal disease. In addition, it is not recommended for long-term use in children. Likewise, people with psoriasis risk severe flare-ups while taking Plaquenil and should not take this medication unless their doctor decides it’s necessary and the benefits outweigh the risks. 

Further, Plaquenil is not effective in treating or preventing forms of malaria that are resistant to the drug. 

Potential side effects of Plaquenil

Like other medications, Plaquenil carries a risk of side effects. However, most are mild and resolve within a few days or weeks.¹²

Common side effects

The more common side effects that can occur with Plaquenil include:

  • Headaches

  • Dizziness

  • Diarrhea

  • Stomach cramps

  • Vomiting

  • Unintended weight loss

Mild side effects may improve over time. Speak with your doctor or pharmacist if they’re severe or persistent.

Severe side effects

Call your doctor right away if you have severe side effects. Call 911 if your symptoms feel life-threatening or if you think you’re having an allergic reaction. Serious side effects and their symptoms can include the following:

  • Hives (itchy welts on your skin)

  • Persistent sore throat or fever (or both)

  • Muscle weakness

  • Mental health effects (including mood changes or suicidal thoughts)

  • Unexplained bleeding or bruising

  • Signs of low blood sugar, including dizziness, anxiousness, confusion, or shaking

  • Vision changes, including blurred vision

  • Hearing changes, including loss of hearing or ringing in the ears (tinnitus)

  • Hair changes, including hair falling out or changing color 

  • Sudden and rapid swelling of the skin (angioedema)

  • Bronchospasm (that may make it difficult to breathe)

  • Convulsions

  • Muscle twitches

  • Changes in heart rate, rhythm, or speed

  • Signs of liver damage (abdominal pain, dark urine, and yellow skin or eyes)

Rarely, using Plaquenil may lead to severely low blood sugar, permanent vision changes, and heart disease or heart failure that may be fatal. Don’t hesitate to seek medical advice if you’re experiencing side effects, as they may indicate the presence of serious complications.


Never take more Plaquenil than your doctor recommends. Exceeding the recommended dosage of Plaquenil can result in adverse effects and could be fatal.

Symptoms of overdose

Signs of an overdose may include:¹²

  • Headache

  • Drowsiness

  • Slow heartbeat or irregular heart rhythm

  • Respiratory failure

  • Cardiac arrest

  • Seizures

  • Vision problems, such as temporary blindness

Missed doses

If you forget to take a dose of Plaquenil, take it as soon as you remember. However, if it is almost time for your next dose, skip the missed dose and continue with your regular schedule. Do not take a double dose to make up for a missed one.

Allergy information

Plaquenil can cause an allergic reaction in some people. 

Symptoms of an allergic reaction can include:

  • Skin rash

  • Itchiness

  • Flushing (temporary warmth, redness, or deepening of skin color)

  • Difficulty breathing

  • Swelling in the throat, face, or both

If you experience an allergic reaction to Plaquenil, stop taking the medication and call 911 or your local emergency number immediately, as this is a medical emergency that could be fatal if not treated urgently.

Long-term use of Plaquenil

People taking Plaquenil for lupus erythematosus or rheumatoid arthritis may take Plaquenil for longer. Unfortunately, the risk of complications increases when the drug is taken long-term or in higher doses. Possible complications associated with long-term use of Plaquenil include:¹¹

Ocular changes

Long-term use of Plaquenil increases the risk of several eye conditions that may cause permanent vision loss or blindness. The drug can affect the ciliary body (a structure located behind the colored part of the eye), the cornea (the eye’s clear outer layer), the retina (a thin layer at the back of the eye), and more. Since all these parts are essential, any changes can cause visual disturbances (including blurred vision, blind spots, light sensitivity, and complete vision loss), which may be temporary or permanent. 

In cases of retinal damage linked to Plaquenil, damage can progress even after the medication is stopped. 

People taking Plaquenil long-term should remain vigilant about changes in vision and will need regular eye exams to check for changes.

Cardiac problems

Plaquenil may trigger heart troubles, including cardiomyopathy, which may result in heart failure or death. Prolonged QR intervals with irregular heart rates have also been reported in some cases with long-term use. 

Central nervous system changes

Central nervous system damage linked to long-term Plaquenil use may lead to physical or mental health issues, including headaches, seizures, nervousness, nightmares, psychosis, dizziness, involuntary and repetitive eye movements, and poor muscle control. 

Neuromuscular changes

The neuromuscular system includes all the body’s muscles and the communication pathways that serve them. Long-term use of Plaquenil increases the risk of neuromuscular changes, including muscle weakness, uncontrollable muscle movements, a decline in tendon reflexes, and sensory changes.

Ear and labyrinth disorders

Plaquenil may trigger ear and labyrinth disorders, including tinnitus, vertigo, or deafness.

Other possible complications of long-term use include:

  • Skin changes

  • Blood composition changes

  • Gastrointestinal issues

  • Allergic reactions

  • New or worsening psoriasis symptoms 

You'll need regular checkups with your doctor if you take Plaquenil long-term. Alongside the essential eye exams, your doctor may recommend blood tests, physical tests, and other assessments. 

Pregnancy category

Plaquenil has not been formally assigned a pregnancy category by the US FDA.

Plaquenil in pregnancy and breastfeeding

No increase in the rate of birth defects has been demonstrated in the available human studies. Adverse effects on the fetus have only been found in rat studies with large doses. When taken according to your doctor’s advice for the treatment of malaria, rheumatoid arthritis, or lupus, it is advised to continue taking the medication during pregnancy as if these conditions are not treated; this could harm the fetus, potentially causing premature birth or growth issues.¹¹

Caution should be taken when using Plaquenil during breastfeeding as it can pass in small amounts through the breast milk. Consult your doctor if you are pregnant, nursing, or intending to become pregnant or breastfeed while taking Plaquenil. They can advise you on what to do, how to take the medication or stop it safely if needed.

Drug interactions

The oral tablet hydroxychloroquine may interfere with other drugs you’re taking. When a chemical alters the way a drug functions, it’s referred to as an interaction. This can make a drug more or less effective or affect the way it works.

In particular, you should inform your doctor and exercise caution when taking Plaquenil if you’re taking any of the following medications:¹¹

  • Digoxin: Digoxin is used to treat heart conditions. Plaquenil may increase the concentration of digoxin in the blood.

  • Insulin or diabetes medications: In people taking medications to lower blood sugar, Plaquenil may cause blood sugar to drop too low.

  • Certain drugs affecting heart rhythm: Plaquenil can cause prolonged QT interval and should not be administered with other drugs that have the potential to induce cardiac arrhythmia.

  • Mefloquine: Mefloquine is another drug used to treat malaria. Combining this medication with Plaquenil may cause convulsions (seizures).

  • Antiepileptic drugs: Plaquenil may impair the effectiveness of antiepileptic drugs.

  • Cyclosporin: Cyclosporin is an immunosuppressant. Plaquenil can increase its concentration in the blood.

  • Praziquantel: Plaquenil may reduce the body’s ability to absorb and utilize praziquantel, which is prescribed to treat certain infections.

  • Antacids and kaolin: These medications may reduce the absorption of Plaquenil, and the drugs should be taken at least four hours apart.

  • Cimetidine: This heartburn medication may affect the body’s metabolism of Plaquenil, resulting in higher concentrations of the drug in the blood.

  • Ampicillin: Ampicillin is an antibiotic. Plaquenil may significantly reduce the bioavailability of ampicillin.

Can I drink alcohol while taking Plaquenil?

There’s no known interaction between Plaquenil and alcohol; however, people with alcoholism should speak with a doctor about their condition before starting Plaquenil due to potential liver impairment.

What to discuss with your doctor before starting Plaquenil

Before taking Plaquenil, speak with your doctor about what to expect. Bring a list of all medications and supplements you’re using (or used long-term in the past), and let your doctor know if you’re pregnant or breastfeeding. Inform your doctor of any existing health conditions, including:¹²

  • Vision issues

  • Heart disease

  • Kidney disease

  • Liver disease

  • Alcoholism

  • Mental health issues

  • Psoriasis

  • Blood disorders

  • Glucose-6-phosphate dehydrogenase (G6PD) deficiency 

  • Stomach issues

  • Any drug allergies or previous negative reactions 

Stopping Plaquenil

It's unlikely that stopping Plaquenil therapy will have any negative consequences.

If you're using Plaquenil to treat lupus or rheumatoid arthritis, keep in mind that the symptoms of your disease may worsen if you discontinue treatment. This is because Plaquenil helps to control the indicators of these illnesses. As a result, stopping treatment with Plaquenil might lead to an increase in joint pain, a worsening of skin rashes, and an increase in the number of flares. However, if there is no improvement in your symptoms after six months of taking Plaquenil, your doctor will probably advise you to stop taking this medication and offer an alternative.

If you're taking Plaquenil to prevent malaria, you'll need to continue taking it for four weeks after you've returned from your trip to ensure you're no longer at risk for the disease.

If you experience any serious adverse effects, you should stop taking Plaquenil and contact your doctor or emergency services.

If you have problems after stopping Plaquenil treatment, speak with your doctor or pharmacist.

Drug approval history

Hydroxychloroquine (Plaquenil) was initially proposed as a safer alternative to another malaria medication, chloroquine. The initial US FDA approval was in 1955.  

Tips for taking Plaquenil

If you are prescribed Plaquenil, it’s essential to be aware of the drug's potential side effects and how to take it safely. Here are some general tips for taking Plaquenil:

  • Take Plaquenil exactly as prescribed by your doctor. Do not exceed the dosage recommended by your doctor, as this can increase your risk of side effects.

  • It is important to drink plenty of water while taking Plaquenil, as dehydration can increase your risk of side effects.

  • Avoid sun exposure while taking Plaquenil, as it can increase your risk of sunburn. Wear sunscreen and protective clothing when outdoors.¹³

  • If you experience any side effects while taking Plaquenil, contact your doctor or call 911 immediately.

  • Do not discontinue the medication without first consulting your doctor.

Plaquenil frequently asked questions

Can you take Plaquenil for life?

Depending on the condition it’s treating, some people may take Plaquenil for life. For example, in a person with lupus whose condition is well-controlled with Plaquenil, symptoms would return if they stopped taking the medication.

Is Plaquenil considered a steroid?

Plaquenil is not a steroid.

Does Plaquenil cause weight gain or weight loss?

There’s no evidence that Plaquenil causes weight gain; however, unintended weight loss is a known side effect.

Curious about clinical trials?

Access the latest treatments and medications. unavailable elsewhere - entirely free of charge. We make it easy to take part.


Here at HealthMatch, we’ve done our best to ensure that the information provided in this article is helpful, up to date, and, most importantly, accurate.

However, we can’t replace the one-to-one advice of a qualified medical practitioner or outline all of the possible risks associated with this particular drug and your circumstances.

It is therefore important for you to note that the information contained in this article does not constitute professional medical or healthcare advice, diagnosis or recommendation of treatment and is not intended to, nor should be used to, replace professional medical advice. This article may not always be up to date and is not exhaustive of all of the risks and considerations relevant to this particular drug. In no circumstances should this article be relied upon without independent consideration and confirmation by a qualified medical practitioner.

Your doctor will be able to explain all possible uses, dosages, precautions, interactions with other drugs, and other potential adverse effects, and you should always talk to them about any kind of medication you are taking, thinking about taking or wanting to stop taking.

Curious about clinical trials?

Access the latest treatments and medications. unavailable elsewhere - entirely free of charge. We make it easy to take part.