Valtrex (Valacyclovir) Medication Information
Valtrex is an antiviral medication that treats different types of herpes infections. Valtrex is indicated to treat the following:
- Genital herpes
- Herpes zoster (chickenpox and shingles)
- Herpes labialis (cold sores)
The herpes family of viruses includes several different variations that can affect the mouth, eyes, genitals, and skin. Infection with these viruses is characterized by an acute outbreak followed by chronic infection. The chronic infection may remain asymptomatic for years, with symptoms only coming back when the immune system is weakened.
When a person takes Valtrex, the body breaks it down into the active drug acyclovir in the stomach and liver. Acyclovir prevents herpes viruses from replicated by incorporating into their DNA, preventing them from making copies.
The adult dosage is determined by the type of virus and whether symptoms are happening or not:
- Cold sore episode: 2 grams by mouth every 12 hours for one day
- Genital herpes episode: 1 gram by mouth twice daily for ten days
- Genital herpes recurrent episode: 500 mg by mouth twice daily for three days
- Suppressive therapy to prevent the transmission of genital herpes to a partner: 500 mg by mouth once daily
The doses for pediatric patients is different than those listed above. Always follows the directions from your doctor when prescribed Valtrex.
Take each dose of Valtrex with a large glass of water to prevent it from building up in the kidneys and causing damage.
Common side effects of Valtrex may include:
- Abdominal pain
- Increased liver enzymes in HIV infected patients
- Neutropenia in HIV infected patients
Tell your doctor if you have a history of kidney problems and all of the drugs you are taking that might worsen kidney function. Valtrex can worsen kidney damage in certain patients.
Valtrex can cause symptoms like confusion and agitation in older patients or those with poor kidney function.
Valtrex can interact with the following medications:
- Varicella virus vaccine
- Zoster vaccine
Always tell your doctor and pharmacist about all of the medications you are taking.
Store Valtrex near room temperature between 15° to 25°C (59° to 77°F).
- You can take Valtrex any time of the day, with or without food.
- Do not stop taking Valtrex even if your symptoms improve. Finish the entire course prescribed by your doctor.
- Valtrex is converted to acyclovir (brand name Zovirax) in the body, so do not take Valtrex if you have an allergy to Zovirax.
How long do I need to take Valtrex?
Some people take Valtrex short-term, some use it episodically, and some take it long-term. Talk with your doctor about how long you will need to take it.
How do I know if Valtrex is working?
If you are taking it for an outbreak, your symptoms should improve within a day or two.
What infections is Valtrex approved to treat?
Valtrex is commonly used to treat cold sores, shingles, chicken pox, and genital herpes.
- Valtrex [package insert]. Greenville, NC: GlaxoSmithKline; 2008.
Author: Dr. Conor Sheehy, PharmD, BCPS
Dr. Sheehy is a board-certified pharmacotherapy specialist. He has worked in multiple practice settings, including retail and hospital pharmacies, and in medical clinics. He specializes in anticoagulation, psychiatric medications, and diabetes medications. He strives to empower his patients to understand their medications and improve their overall medical care.
The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.