Valtrex is the trade name for the antiviral medication valacyclovir. It is indicated for the treatment of oral herpes, genital herpes, herpes-zoster and chickenpox. Valtrex was first approved by the U.S. Food and Drug Administration in 1995 and has been studied extensively in clinical trials and post-marketing research. The effects of Valtrex can vary depending on which condition it is prescribed for. The effects also differ with special patient populations. Overall, Valtrex has been proven to be safe and effective, but comes with several side effects ranging from mild to serious.
Treatment and Prevention
Valtrex is used to treat herpes viruses and the chickenpox virus, and it works by inhibiting viral DNA replication. Valtrex provides a high bio-availability of the active ingredient acyclovir. According to the prescribing label for Valtrex, it shortens the duration of herpes-zoster and cold sore lesions by one day, and the duration of genital herpes lesions by two days.
Using Valtrex as a way to reduce or prevent recurrence is also an effective measure. In the June 2008 issue of the "Archives of Internal Medicine," Dr. Christina Cernik and associates reported that 500 mg of daily preventive Valtrex resulted in 60 percent of patients remaining free from cold sore flareups, compared with 38 percent taking a placebo. The prescribing label for Valtrex states that daily preventive doses of 1 gm for 12 months resulted in 46 percent of patients experiencing a recurrence of genital herpes, compared with 85 percent of patients taking a placebo. Valtrex also reduces the transmission of genital herpes from one partner to the next.
Side Effects
Valtrex can cause several side effects ranging from mild to serious. According to eMedTV, the most common side effect is a headache, occurring in up to 38 percent of patients. Nausea and abdominal pain occur in 15 and 11 percent of patients, respectively. Eight percent of female patients experienced painful menstrual periods. Other common side effects include depression, vomiting, joint pain, increased liver enzymes and dizziness. EmedTV also states that patients who are infected with HIV experience additional side effects from Valtrex, including unexplained rash, fatigue and decreased blood counts.
Warnings and Precautions
There are also a few warnings and precautions regarding the effects of Valtrex. According to Drugs.com, patients have experienced acute kidney failure and serious negative central nervous system effects. Acute kidney failure has occurred in healthy elderly patients, patients taking other medications that compromise the kidneys and patients who are not properly hydrated. In addition, kidney failure has also occurred in patients with pre-existing kidney disease who take higher levels of Valtrex than recommended. The warning about central nervous system effects states that patients can experience agitation, hallucinations, confusion, poor concentration and seizures. Elderly patients are more likely to experience a negative central nervous system response. Drugs.com also states that patients should discontinue using Valtrex if negative central nervous system reactions occur.
References
- Drugs.com: Valtrex Prescribing Information
- "Journal of the American Dental Association"; The Efficacy of Valacyclovir in Preventing Recurrent Herpes Simplex Virus Infections Associated With Dental Procedures; Dr. Craig S. Miller et al.; September 2004
- "Archives of Internal Medicine"; The Treatment of Herpes Simplex Infections; Dr. Cristina Cernik et al.; June 2008
- Glaxo Smith Kline: Valtrex Prescribing Label
- eMedTV: Valtrex Side Effects
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