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. Plaquenil prednisone How does plaquenil affect sleep It can also be used pretty much indefinitely, as long as there is no sign of eye problems. Occasionally, someone will really have no measurable response to Plaquenil, but most docs will allow at least 6 months for that decision to be made because the lag time from taking the medicine to its effectiveness is so long. Hydroxychloroquine typically is very well tolerated. Serious side effects are rare. The most common side effects are nausea and diarrhea, which often improve with time. Less common side effects include rash, changes in skin pigment such as darkening or dark spots, hair changes, and muscle weakness. Plaquenil hydroxychloroquine belongs to a group of medicines called quinolines. Plaquenil is used to treat or prevent malaria, a disease caused by parasites that enter the body through the bite of a mosquito. Malaria is common in areas such as Africa, South America, and Southern Asia. 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. Plaquenil knee side effects Plaquenil side effects - kidney problems? - Symptoms - Life., Hydroxychloroquine Plaquenil Dry skin from plaquenil Some side effects of hydroxychloroquine 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. Hydroxychloroquine Side Effects -. Plaquenil Uses, Dosage & Side Effects -. Plaquenil Hydroxychloroquine Uses, Dosage, Side Effects.. Get medical help right away if you have any very serious side effects, including sensitivity to light, vision changes e.g. blurred vision, seeing light flashes/streaks/halos, missing/blacked-out areas of vision, muscle weakness, numbness/tingling/pain of the arms/legs. Plaquenil hydroxychloroquine is in a class of drugs called disease-modifying anti-rheumatic drugs, which are used to decrease inflammation, pain and joint damage. While today it is used to treat autoimmune conditions, such as rheumatoid arthritis and lupus, it was originally used as an anti-malaria drug. Serious Side Effects of Plaquenil. If you are taking Plaquenil long-term, such as for an autoimmune condition, your doctor should regularly check you for potential serious side effects.