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. Chloroquine dose per kg Plaquenil long term use side effects Plaquenil blood thinner Side Effects Nausea, stomach cramps, loss of appetite, diarrhea, dizziness, or headache may occur. If any of these effects persist or worsen, notify your doctor or pharmacist promptly. Remember. Side effects from chloroquine phosphate can occur. Tell your doctor if any of these symptoms are severe or do not go away headache; loss of appetite; diarrhea; upset stomach; stomach pain; skin rash or itching; hair loss; mood or mental changes; If you experience any of the following symptoms, call your doctor immediately seeing light flashes and streaks Headache with chest pain and severe dizziness, fainting, fast or pounding heartbeats; very slow heart rate, weak pulse; muscle weakness, numbness or tingling; low blood sugar--headache, hunger, sweating, irritability, dizziness, nausea, fast heart rate, and feeling anxious or shaky; or 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. Chloroquine headache Chloroquine Oral Uses, Side Effects, Interactions, Pictures., Chloroquine MedlinePlus Drug Information Nonbiological dmard antimalarial hydroxychloroquine plaquenil Chloroquine is effective against susceptible strains of the malarial parasites Plasmodium vivax, P. ovale, and P. falciparum, as well as certain parasitic worms and amoebas. Some mild side effects may occur, including headache and abdominal cramps, which are common to antimalarials. Visual impairment may occur with long-term use of chloroquine. Chloroquine drug Britannica. Side Effects of Plaquenil Hydroxychloroquine, Warnings, Uses. Plaquenil Hydroxychloroquine - Side Effects, Dosage.. Chloroquine is used to prevent or treat malaria caused by mosquito bites in countries where malaria is common. Malaria parasites can enter the body through these mosquito bites, and then live in body tissues such as red blood cells or the liver. Adverse effects Seizures. Deafness or tinnitus. Nausea, vomiting, diarrhea, abdominal cramps, and anorexia. Mild and transient headache. Skin itchiness, skin color changes, hair loss, and skin rashes. Unpleasant metallic taste. Chloroquine retinopathy. Hypotension and electrocardiographic. Before taking hydroxychloroquine, tell your doctor and pharmacist if you are allergic to hydroxychloroquine, chloroquine Aralen, primaquine, or any other drugs. tell your doctor and pharmacist what prescription and nonprescription drugs you are taking, especially acetaminophen Tylenol, others, digoxin Lanoxin.