What is Hydroxychloroquine Sulfate: Uses, Warnings & Interactions

Take this medicine as directed.

If used for malaria prevention or treatment, take all of the medicine in your prescription even if you feel fine.

Take the tablets with food or milk to prevent stomach problems.

Swallow the tablet whole. Do not crush or divide the tablet. 

Store the medicine in a closed container at room temperature.

If you take one dose a week, take the missed dose as soon as possible. Then return to your regular dosing schedule.

If you are taking hydroxychloroquine to treat an active malaria infection and you miss a dose, call the prescriber or other healthcare professional for advice.

If you take one or more doses daily, take the missed dose as soon as possible. If it is almost time for your next dose, wait until then to take your medicine and skip the missed dose.

You should not use two doses at the same time.

This medicine is not right for everyone.

Do not use it if you have had an allergic reaction to hydroxychloroquine or related antimalarial drugs (such as chloroquine, primaquine, or mefloquine).

Tell any doctor or other healthcare provider who treats you that you are using this medicine.

Your doctor may do lab tests at regular visits to check on the effects of this medicine. Keep all appointments.

Hydroxychloroquine can be toxic to the heart, causing potentially fatal heart problems and changes in heart rhythm. Before taking hydroxychloroquine, tell your doctor if you have:

• A history of heart disease

• A history of heart rhythm problems

• A type of heart rhythm problem called QT prolongation

• Low potassium or low magnesium

Hydroxychloroquine can be toxic to the eye’s retinas, causing irreversible vision changes. Long-term or high-dose treatment raises the risk of retinal damage. Before taking hydroxychloroquine, tell the doctor if you:

• Have macular degeneration or other eye problems

• Have kidney disease

• Are taking the breast cancer drug tamoxifen

Also tell your doctor if you have:

• Liver disease

• Diabetes

• Stomach or bowel problems

• Nerve problems

• Blood disorders

• Psoriasis

This medicine may cause other problems such as:

• Muscle and nerve problems

• Kidney damage

• Changes in mood or behavior

• Thoughts of suicide

• Low blood sugar levels

• Worsening of psoriasis

• Serious skin reactions

Tell the doctor if you’re pregnant or breastfeeding.

This medicine may make you bleed, bruise, or get infections more easily. Take precautions to prevent illness and injury.

To avoid potentially hazardous drug interactions, tell the prescribing healthcare provider about all prescription drugs, over-the-counter medicines, and supplements you are using before taking hydroxychloroquine.

Tell other healthcare providers you are using this medicine before they prescribe new medications.

Avoid using the stomach acid reducer Tagamet (cimetidine) when taking hydroxychloroquine.

Take antacids or kaolin at least 4 hours before or after taking this medicine.

Do not drink alcohol while you are using this medicine.

Some medicines can affect how hydroxychloroquine works or may increase the risk of side effects. These include:

• Drugs that increase the risk of seizures

• Drugs that affect the heart’s rhythm (QT prolongation)

• The immune suppressants methotrexate and cyclosporine

• The antibiotic ampicillin

• The heart failure drug digoxin

• The breast cancer drug tamoxifen

• Praziquantel 

Some medications don’t work as well as they should when used with hydroxychloroquine, especially insulin, diabetes medications, and anticonvulsants. 

Find out more about hydroxychloroquine interactions to avoid here.