New TI Study on Drug Safety Advisories on Hydroxyzine

New TI Study on Drug Safety Advisories on Hydroxyzine

In our continued examination of drug safety warnings, researchers with UBC’s Therapeutics Initiative, and others found that warnings about heart risks associated with the antihistamine drug hydroxyzine led to reduced prescribing in the UK but not in BC. This study, just published in the journal Drug Safety,  included data from the UK and BC for patients visiting a physician for a condition commonly treated with hydroxyzine, such as eczema, rash or allergy.

Drug safety advisories issued in the UK in April 2015 and in Canada in June 2016 warned about the possible association of hydroxyzine with abnormal heart rhythms known as QT prolongation and Torsade to Pointes. These adverse effects may lead to sudden cardiac death.

New prescribing of hydroxyzine declined by 21% in the UK in the year after drug safety advisories were issued in the country. In BC, new prescribing of hydroxyzine was already declining prior to a similar Canadian drug advisory. Researchers expected the Canadian drug warning might lead to a steeper decline in hydroxyzine prescribing, but the advisory was not associated with a change in the trend of new prescribing in BC.

“It was surprising to find that the Canadian advisory had little impact on new prescribing of hydroxyzine in BC,” said lead author Richard Morrow, “even though a similar advisory in the UK led to changes in prescribing.”

Researchers found that in the two years following the UK advisories, physicians in the UK adjusted their prescribing of hydroxyzine based on patient risk factors. Physicians reduced new prescribing of hydroxyzine to patients with pre-existing heart conditions by about one-third and to patients with recent use of QT-prolonging drugs with known risk of Torsade de Pointes by about one-half, compared with only one-quarter for patients without risk factors.

“It is important that physicians in the UK reduced their new prescribing of hydroxyzine based on patient risk factors highlighted in the drug warnings,” Morrow noted. “It is reasonable to expect that reducing prescribing to higher-risk patients would be more likely to reduce drug-related adverse events.”

The full article is available at


For further information or to arrange an interview with the research team contact:

Alan Cassels, Communications Director
Therapeutics Initiative    +1250-508-8996 | | @akecassels

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