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 while taking hydroxychloroquine: Incidence not known Some side effects of hydroxychloroquine may occur that usually do not need medical attention. Ra treatment plaquenil methotrexate Average weight loss on plaquenil What happens if you stop plaquenil Find patient medical information for Plaquenil Oral on WebMD including its uses, side effects and safety, interactions, pictures, warnings and user ratings. PLAQUENIL prescription and dosage sizes information for physicians and healthcare professionals. Pharmacology, adverse reactions, warnings and side effects. Along with its needed effects, hydroxychloroquine the active ingredient contained in Plaquenil 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 while taking hydroxychloroquine Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. These side effects may go away during treatment as your body adjusts to the medicine. Drug warnings for plaquenil Plaquenil Hydroxychloroquine - Side Effects, Dosage., PLAQUENIL Dosage & Rx Info Uses, Side Effects Atovaquone proguanil chloroquine doxycycline or mefloquine Drugs that prolong QT interval and other arrhythmogenic drugs Plaquenil prolongs the QT interval and should not be administered with other drugs that have the potential to induce cardiac arrhythmias. Also, there may be an increased risk of inducing ventricular arrhythmias if Plaquenil is used concomitantly with other arrhythmogenic drugs. Plaquenil - FDA prescribing information, side effects and uses. Plaquenil Side Effects Common, Severe, Long Term -. Hydroxychloroquine Side Effects -. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects, nor should it be construed to indicate that use of a particular drug is. Plaquenil Warnings. Take with food. Take this medication at least 4 hours before or 4 hours after antacids. Avoid prolonged or excessive exposure to direct and/or artificial sunlight while using this medication. WARNING Keep Out of the Reach of Children. Fatal Poisoning may occur if chewed or swallowed. If you are taking Plaquenil to treat an inflammatory condition or malaria, you should be aware of the side effects that may occur to your eyes and vision. Plaquenil hydroxychloroquine is in a class of drugs called disease-modifying anti-rheumatic drugs, which are used to decrease inflammation, pain and joint damage.