Side Effects of Valacyclovir

During extensive clinical trials studying the side effects of valacyclovir, headaches were reported the most often. Other common side effects include nausea, abdominal pain, and dizziness. Some side effects of valacyclovir should be reported immediately to your healthcare provider, including unexplained swelling, hallucinations, or difficulty swallowing. Rare side effects include diarrhea, hair loss, and kidney failure.

 

Side Effects of Valacyclovir: An Introduction

As with any medicine, there are possible side effects of valacyclovir hydrochloride (Valtrex®). However, not everyone who takes this drug will experience side effects. In fact, most people tolerate valacyclovir quite well. If side effects do occur, in most cases, they are minor, meaning they require no treatment or are easily treated by you or your healthcare provider.
 
(The valacyclovir side effects discussed below are not a complete list of reported side effects. Your healthcare provider can discuss a more complete list with you.)
 

Common Side Effects of Valacyclovir

Valacyclovir has been thoroughly studied in clinical trials, with many people being evaluated. In these studies, side effects occurring in the group of people taking the drug are always documented and compared to the side effects that occurred in a similar group of people not taking the medicine. Based on these studies, the most common valacyclovir side effects include:
 
  • Headache -- occurring in up to 38 percent of people
  • Nausea (upset stomach) -- in up to 15 percent
  • Abdominal pain (or stomach pain) -- in up to 11 percent
  • Painful menstrual periods -- in up to 8 percent
  • Depression -- in up to 7 percent (see Valtrex and Depression)
  • Vomiting -- in up to 6 percent
  • Joint pain -- in up to 6 percent
  • Increased liver enzymes -- in up to 4.1 percent
  • Dizziness -- in up to 4 percent.
     
People with HIV who take valacyclovir may have additional side effects or side effects that occur more frequently. Other common side effects include an unexplained rash, fatigue (tiredness), and decreased blood counts.
 
(Side Effects of Valacyclovir Continued: Page 2)
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Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD;