Hydroxychloroquine Side Effects

American Association of Poison Control Centers on Hydroxychloroquine Side Effects 

Arlington, VA– Hydroxychloroquine and its associated drug, chloroquine, have a variety of well-known adverse side effects. If it is being used in the context of treating the coronavirus, the short duration of therapy will likely avoid many of those. Nevertheless, it’s important to consider certain factors and remind your physician of any underlying illnesses. Additionally, non-pharmaceutical formulations of chloroquine or prescription chloroquine/hydroxychloroquine taken outside of medical supervision can be especially dangerous.

Genetic predisposition: Individuals who have inherited G6PD deficiency may have a serious reaction to hydroxychloroquine. It should be used with extreme caution in people with prolonged QT syndrome or who are on medications for heart rhythm problems as the addition of chloroquine/hydroxychloroquine can increase the risk for fatal dysrhythmia. Azithromycin, which has been suggested by some to be used in combination with hydroxychloroquine for the treatment of COVID, may also cause prolonged QT syndrome increasing the risks of this problem.

Adverse effects for the general population: Some patients taking hydroxychloroquine may experience nausea, vomiting and/or diarrhea. They may also experience headache and dizziness. Irritability, tremor and even changes in mood have been reported. Most of the symptoms will resolve when the drug is discontinued. However, symptoms of adverse drug effects may be difficult to differentiate from symptoms of the virus itself. Hydroxychloroquine may interfere with drugs used for the treatment of diabetes and produce a drop in blood sugar causing symptoms. People with type I or type II diabetes should be aware of this possibility.


As with any drug, allergic reactions may occur. These medications have a narrow therapeutic window meaning that accidental ingestion of amounts that exceed recommended dosing can be extremely dangerous with toxicity including coma, seizures, cardiac dysrhythmias, low potassium levels, cardiac arrest and death.  Even a single pill can be potentially life threatening to a child.


While chloroquine/hydroxychloroquine has demonstrated benefits for multiple chronic autoimmune and rheumatologic diseases, the benefit for treatment of COVID-19 has not been definitively established.  It is critical that any use of these medications is coordinated with a treating physician with full understanding of the potential risks and benefits.

If you have questions about or feel you are having an adverse reaction to hydroxychloroquine, chloroquine, or any other medication, please contact your regional poison control center at 1-800-222-1222 for advice.

About American Association of Poison Control Centers (AAPCC)

AAPCC supports the nation’s 55 poison center members in their efforts to treat and prevent drug, consumer product, animal, environmental and food poisoning. Members staff the Poison Help hotline at 1-800-222-1222 that provides free, confidential, expert medical advice 24 hours a day, seven days a week, 365 days a year. AAPCC partners with federal agencies such as HRSA, CDC, FDA and EPA, as well as private industry. Be prepared for a poison emergency and download poison control’s contact information today. Text “poison” to 797979.

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For More Information,Contact:

Yasmine Harding, Associate Manager,

Public Education & Communications

[email protected]; 703-894-1865