Reported Reactions to Valacyclovir
Common Valacyclovir Side Effects
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. This way, it is possible to see what side effects occur, how often they appear, and how they compare to the group not taking the medicine.
Based on these studies, the most common valacyclovir side effects included:
- 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.
Rare Side Effects With ValacyclovirRare side effects of valacyclovir happen in very few patients taking the medication. Since these side effects are so rare, it is difficult to tell whether they are caused by the valacyclovir or by something else.
Some of these rare side effects include but are not limited to:
- Low blood counts, including low white blood cells (neutropenia), low platelets (thrombocytopenia), or low red blood cells (anemia)
- High blood pressure (hypertension)
- Increased heart rate (tachycardia)
- Behavioral or mental changes
- Vision changes
- Hair loss (see Valtrex and Hair Loss)
- Hepatitis (liver inflammation)
- Kidney failure.