[ hahy-drok-si-klawr-uh-kween, -kwin ]
/ haɪˌdrɒk sɪˈklɔr əˌkwin, -kwɪn /
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noun Pharmacology.
a colorless crystalline solid, C18H26ClN3O, used in the treatment of malaria, lupus erythematosus, and rheumatoid arthritis. Abbreviation: HCQ


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Origin of hydroxychloroquine

First recorded in 1960–65; hydroxy- + chloroquine
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023


What is hydroxychloroquine?

Hydroxychloroquine is a drug used to prevent and treat malaria. It is also used in the treatment of certain inflammatory autoimmune diseases, including rheumatoid arthritis and a form of lupus.

As an antimalarial drug, hydroxychloroquine was first synthesized in the 1940s. By the 1950s, the drug was proven to be effective in treating the symptoms of rheumatoid arthritis and lupus. Hydroxychloroquine remains an important way of controlling lupus in patients to this day.

In the U.S., a prescription is needed for the drug, which is taken orally in the form of a hydroxychloroquine sulfate tablet. Plaquenil is a brand-name preparation of hydroxychloroquine.

Hydroxychloroquine can have a number of side effects, including disruptions in heart rhythms and retinal damage. Less severe side effects include skin rash, nausea, and mood changes. It can also interact with other drugs, including antacids and insulin.

Hydroxychloroquine is closely related to chloroquine, another antimalarial drug (sold under the brand name Aralen). Hydroxychloroquine and chloroquine are included in the World Health Organization’s list of essential medicines.

Both substances are chemically derived from quinoline, a pungent, colorless liquid occurring in coal tar and used to make dyes, among other uses. And while both can have similar side effects, hydroxychloroquine is considered less toxic than chloroquine.

Dig deeper

The chemical formula for hydroxychloroquine is C18H26ClN3O. Hydroxychloroquine is sometimes abbreviated as HCQ.

Hydroxychloroquine is composed of hydroxy, a combining form indicating that the hydroxyl group (a type of bond between oxygen and hydrogen) is present in a chemical compound, and chloroquine. Chloroquine, in turn, is composed of chloro, used in the names of chemical compounds where chlorine is present, and quin(ol)ine.

Now, here’s a word origin you might not have suspected: quinine and quinoline both ultimately derive from the Quechua kina, meaning “bark.” Formerly used against malaria, quinine is present in the bark of various cinchona trees and shrubs, which are native to the Andes. Quechua is an indigenous language of South America, where cinchona bark was originally found.

Does hydroxychloroquine work for coronavirus?

Does hydroxychloroquine work as a treatment for the coronavirus, specifically COVID-19?

At this point, there is no proven or approved treatment for COVID-19. However, hydroxychloroquine and chloroquine, along with other drugs, including the antiviral medication remdesivir , are being tested in clinical trials. More data is needed to determine the safety and effectiveness of the drugs in use against COVID-19.

In late March 2020, the Food and Drug Administration authorized the emergency use of hydroxychloroquine for certain patients hospitalized with COVID-19 and for whom clinical trials are not available or participation in which isn’t feasible.

Do not take hydroxychloroquine to prevent getting COVID-19—and especially without talking to your doctor. Not only might needlessly taking hydroxychloroquine harm your health, it may also contribute to shortages in the drug, which, as noted, is especially vital to people suffering from lupus.

For health, safety, and medical emergencies or updates on the novel coronavirus pandemic, please visit the CDC (Centers for Disease Control and Prevention) and WHO (World Health Organization).

How to use hydroxychloroquine in a sentence