Canadian Product Monograph for Valtrex Now Warns About Risk of Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)
Valtrex (valacyclovir) is a long-established treatment for cold sores, genital herpes, and herpes zoster, having been initially approved by the FDA in 1995. According to the Health Product InfoWatch December 2022 edition released by Health Canada on December 22, 2022, cases of Valtrex-associated DRESS have been reported as a drug side effect.
In more detail, from the Valtrex part of the "New health product safety information" section of this December 2022 Health Canada document:
• [Drug reaction with eosinophilia and systemic symptoms (DRESS)] has been reported in association with [Valtrex (valacyclovir)] treatment. DRESS is a serious skin reaction that may affect one or more organs and can be life-threatening or fatal.
• Patients should be monitored closely for skin reactions and advised of the signs and symptoms of DRESS, including fever, severe rash, peeling skin, facial edema, lymphadenopathy, flu-like feeling, jaundice, dyspnea, dry cough, chest pain or discomfort, dehydration, and eosinophilia.
• If signs and symptoms suggestive of DRESS appear, [Valtrex (valacyclovir)] should be withdrawn immediately and an alternative treatment considered, as appropriate.
• If a patient has developed DRESS with the use of [Valtrex (valacyclovir)], treatment with valacyclovir must not be restarted in this patient at any time.
Further, therein, it is reported that GlaxoSmithKline Inc. has updated the Canadian product monograph for Valtrex to add information about the risk of Valtrex-associated DRESS.
In comparison, the Full Prescribing Information document for Valtrex in the United States does not currently have any discussion of or warning about Valtrex-associated DRESS as a possible side effect. We will watch to see whether the FDA follows the lead of Health Canada and require a Valtrex drug label change to add information about drug reaction with eosinophilia and systemic symptoms (DRESS).
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