Medically reviewed by Kristin Hall, FNP
Written by Our Editorial Team
Last updated 4/26/2020
Valacyclovir (also known as Valtrex), is one of the most common medications used to treat the herpes simplex virus. Used regularly by millions of people worldwide, it’s a safe, highly effective drug that can control from herpes outbreaks and reduce the risk of spreading the virus.
Like other drugs used to treat herpes, valacyclovir is an antiviral medication. It works through a complex mechanism that stops the herpes virus from replicating further within the body, making it useful for a variety of herpes-related conditions.
Valacyclovir is used to treat HSV-1 and HSV-2, as well as the varicella zoster virus (shingles, or VZV). Because of its antiviral properties, it’s also used to prevent cytomegalovirus (CMV) and to limit the effects of viruses in people with weakened immune systems, such as cancer patients.
Below, we’ve listed common valacyclovir dosages for a variety of conditions, such as outbreaks of oral or genital herpes. The dosage information provided below is for adults -- for children, you should consult your doctor, who will provide dosing recommendations based on your child’s age, weight and health.
Note: If you have been prescribed valacyclovir by your doctor to treat any condition, follow the dose and frequency they recommend. The information below is provided as a reference only -- you should always follow your doctor’s advice when using any prescription medication.
Oral herpes is the most common form of the herpes virus, affecting approximately two thirds of all people aged 14 to 49.
Valacyclovir is highly effective at treating oral herpes. Taken early in the formation of a cold sore, repeated use of valacyclovir over the course of one day can reduce the amount of time required for a cold sore to heal.
The typical dose of valacyclovir used to treat cold sores is 2,000 mg, with a secondary dose of 2,000 mg within 12 hours. This repeated, high dose of valacyclovir quickly ends viral replication and allows cold sores to heal one to two days faster than normal.
If you have genital herpes, you’ll understand how stressful an outbreak can be. People infected with genital herpes can experience four to five outbreaks of the virus per year, making it vital to have medication like valacyclovir on hand in the event you notice herpes lesions developing.
Like oral herpes, valacyclovir is highly effective at treating genital herpes and speeding up the healing process.
Genital herpes occurs in two phases. After being infected with the virus, most people will have an initial outbreak -- a powerful outbreak of the virus that can result in severe symptoms. After this, genital herpes presents itself in recurring outbreaks every few months.
The typical dose of valacyclovir used to treat an initial outbreak of genital herpes is 1,000 mg taken two times per day. This twice-daily 1,000 mg dosage usually continues over 10 days as the herpes outbreak retreats and the lesions close, scab and heal.
During a very severe initial outbreak of genital herpes, your doctor might recommend taking valacyclovir over a longer period.
For recurring genital herpes, the typical dosage of valacyclovir is 500 mg taken twice daily for three days.
As with cold sores, valacyclovir is most effective at treating genital herpes when it’s taken as early as possible during an outbreak. Taken early, consistently and at the right dose, use of valacyclovir can make dealing with a difficult genital herpes outbreak more manageable.
Valacyclovir is also used to treat shingles -- a painful form of herpes skin rash caused by the varicella zoster virus.
The standard dose of valacyclovir used to treat shingles is 1,000 mg taken three times every day. Valacyclovir treatment for shingles usually goes on for seven days, although your doctor may recommend continuing valacyclovir if your symptoms are slow to improve.
Just like with cold sores and oral herpes, valacyclovir is most effective when it’s taken as early as possible after noticing shingles symptoms. It’s recommended to begin using valacyclovir in 72 hours or less after noticing signs of a shingles outbreak.
Valacyclovir is also used to treat recurrent outbreaks of shingles. These are extremely rare and tend to occur in people with weakened immune systems due to conditions such as leukemia or HIV, or the use of immunosuppressive medications.
Finally, valacyclovir is also used for suppressive therapy -- a method of reducing the risk of an infected person spreading herpes to their partner or family members, as well as restricting the ability of the virus to cause frequent outbreaks.
The standard dose of valacyclovir for suppressive therapy is 1,000 mg taken once daily. People with HSV-1 or HSV-2 that only experience infrequent outbreaks may also be prescribed a lower dose of 500 mg per day.
Overall, valacyclovir is an extremely safe, well-studied medication. Its side effects are mild and rare, affecting only a small percentage of users. It’s also very safe for the liver and other internal organs, including those commonly affected by other medications.
However, it’s important to speak to your doctor before taking valacyclovir to treat any infection, including herpes. It’s particularly important to speak to your doctor before using valacyclovir if you have HIV or any other health condition that can cause reduced renal or immune function.
Valacyclovir is an affordable, highly effective antiviral medication, making it the “gold standard” for treating outbreaks of herpes and reducing the risk of infecting others with the virus.
Our Valacyclovir 101 guide covers the ins and outs of valacyclovir in more detail, from how the drug works to reduce the spread or herpes and treat outbreaks to the potential side effects you may experience while taking valacyclovir to treat herpes.
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