The patient had been treated with hydroxychloroquine for two years prior to presentation. After thorough workup for secondary causes of QT interval prolongation hydroxychloroquine was discontinued and the patient’s QT interval shortened. Hydroxychloroquine interactions Plaquenil heart Retinal toxicity dosage hydroxychloroquine Commonly used on holidays in malaria prone destinations, chloroquine and hydroxychloroquine will not be over familiar to the emergency physician. However, it is one of the leading causes of drug overdose in malaria prone countries and also the occasional toddler has managed to consume the grandparents lupus or rheumatoid arthritis medication leading to lethal consequences. Drug-induced QT/QTc interval prolongation is a surrogate indicator for increased risk of drug-induced torsade de pointes TdP, a potentially lethal polymorphic ventricular tachycardia. Risk factors for drug-induced QT/QTc prolongation include female gender, Hydroxychloroquine is usually taken with food or milk to prevent stomach upset. The dosage and length of treatment are based on your medical condition and response to therapy. In children, dosage is also based on weight. The patient was noted to have mild prolongation of the QT interval on electrocardiogram prior to initiation of hydroxychloroquine therapy which was exacerbated by its use and may have been caused due to toxicity from underlying renal failure. The patient was treated with mexiletine to prevent sudden ventricular arrhythmias, which was unique compared to other documented cases in which lidocaine was used. Hydroxychloroquine qt prolongation Long QT Syndrome LQTS, The cardiotoxicity of antimalarials Plaquenil discountHydroxychloroquine sulfate allergy Chronic hydroxychloroquine use associated with QT prolongation and refractory ventricular arrhythmia. Clin Toxicol Phila. 2006; 442173-5 ISSN 1556-3650 Chen CY; Wang FL; Lin CC. BACKGROUND Hydroxychloroquine HCQ is used for treatment of lupus erythematosus. The cardiac toxicity of HCQ has focused primarily on acute intoxication. Chronic hydroxychloroquine use associated with QT.. Hydroxychloroquine Oral Uses, Side Effects, Interactions.. Long QT and Hydroxychloroquine; A Poorly Recognised Problem.. Of the documented medications known to cause QT interval prolongation hydroxychloroquine HCQ is extremely rare in the literature. HCQ is an antimalarial that has become the cornerstone for treatment of systemic lupus erythematosus SLE 9. Make sure your doctor knows if you had a heart rhythm problem such as QT prolongation. This medicine may cause muscle and nerve problems. Check with your doctor right away if you have muscle weakness, pain, or tenderness while using this medicine. Hydroxychloroquine may cause some people to be agitated, irritable, or display other abnormal behaviors. Hydroxychloroquine may cause a condition that affects the heart rhythm QT prolongation. QT prolongation can rarely cause serious rarely fatal fast/irregular heartbeat and other symptoms such as severe dizziness, fainting that need medical attention right away. The risk of QT prolongation may be increased if you have certain medical conditions or are taking other drugs that may cause QT prolongation.