Valacyclovir is an antiviral medication used to treat cold sores, initial or recurrent genital herpes, and shingles. These infections can cause symptoms such as burning, pain, and blisters on the skin or mucous membranes.
This medication works by reducing the replication of herpes viruses, which helps prevent the virus from infecting new cells and can shorten the duration of symptoms. In people with shingles, valacyclovir can also help reduce acute pain and shorten the duration of pain associated with the infection.
Valacyclovir is available in US pharmacies as 500 mg and 1 g tablets, including generic versions and the brand-name medication Valtrex. It should only be used as prescribed by a healthcare provider.
What is valacyclovir used for?
Valacyclovir is indicated for the treatment of:
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Shingles (herpes zoster), helping reduce acute pain and shorten the duration of pain;
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Cold sores (herpes labialis), particularly when treatment is started at the first symptoms;
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Initial and recurrent genital herpes.
For the prevention of cytomegalovirus (CMV) disease after certain organ transplants, valganciclovir is an FDA-approved antiviral option in the United States for patients at high risk. Valacyclovir is not FDA-approved in the US for this indication.
Does valacyclovir cure herpes?
Valacyclovir, like other antiviral medications, does not cure herpes, whether it causes cold sores, genital herpes, or shingles. It does not eliminate the virus from the body and instead works by reducing viral replication, shortening the duration of symptoms, and limiting infection of new cells.
There is no treatment that completely eliminates herpes simplex virus or varicella-zoster virus from the body. These viruses can remain inactive in the body and may become active again later.
How to take valacyclovir
Valacyclovir tablets should be taken by mouth with a glass of water, with or without food, at the times and for the length of treatment prescribed by a healthcare provider.
It is important to stay well hydrated while taking valacyclovir, especially because the medication is eliminated through the kidneys. The dose may need to be adjusted in people with impaired kidney function.
Valacyclovir dosage
Valacyclovir dosage varies depending on the condition being treated and may include:
1. Genital herpes
For the treatment of genital herpes in adults, the recommended doses include:
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Initial infection (first episode of genital herpes): 1 g of valacyclovir twice a day, about every 12 hours, for 7 to 10 days. FDA-approved labeling specifies 1 g twice daily for 10 days, while CDC treatment guidelines recommend 7 to 10 days. Treatment should be started as soon as possible after symptoms appear;
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Recurrent infection: 500 mg of valacyclovir twice a day for 3 days. Treatment should ideally be started as soon as the first signs or symptoms of genital herpes appear.
Valacyclovir may also be used as suppressive therapy for recurrent genital herpes. For adults with normal immune function, the usual FDA-approved dose is 1 g once a day, although 500 mg once a day may be considered for people with 9 or fewer recurrences per year.
People taking valacyclovir for long-term suppressive therapy should have regular medical follow-up. Kidney function may need to be monitored, particularly in older adults or people with kidney impairment, because dose adjustments may be necessary.
Topical antiviral medications provide minimal benefit for genital herpes and are generally not recommended. Oral antiviral medications are the main form of treatment.
2. Cold sores
For the treatment of cold sores in adults and adolescents 12 years and older, valacyclovir should be started at the earliest symptom, such as tingling, itching, or burning.
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Treatment of cold sores: 2 g of valacyclovir twice in 1 day, with the second dose taken about 12 hours after the first.
Treatment should not last longer than 1 day for this indication. The effectiveness of starting valacyclovir after a visible bump, blister, or ulcer has already developed has not been established.
3. Shingles
For the treatment of shingles in adults, the usual recommended dose is 1 g of valacyclovir 3 times a day, about every 8 hours, for 7 days.
Valacyclovir can help reduce symptoms and pain caused by shingles. A shingles vaccine is also available to help prevent shingles and related complications.
Possible side effects
The most common side effects of valacyclovir include headache, nausea, and abdominal pain.
Less common but potentially serious side effects should be reported to a healthcare provider promptly. These may include confusion, dizziness, hallucinations, agitation, difficulty speaking, seizures, or other neurological symptoms, particularly in older adults or people with impaired kidney function.
Medical attention is also important if symptoms of kidney problems develop, such as producing very little or no urine, swelling, unusual tiredness, or difficulty breathing. Valacyclovir can cause acute kidney problems, particularly when the dose is too high for a person's level of kidney function or when adequate hydration is not maintained.
Who should not take valacyclovir?
Valacyclovir should not be used by people who have had a clinically significant allergic reaction to valacyclovir, acyclovir, or any component of the medication.
During pregnancy or breastfeeding, valacyclovir should only be used under medical guidance after a healthcare provider considers the expected benefits and potential risks.
What is the difference between valacyclovir and acyclovir?
Valacyclovir and acyclovir are both antiviral medications used to treat herpes infections, including initial and recurrent genital herpes.
The main difference is that valacyclovir is a prodrug of acyclovir. After valacyclovir is absorbed, the body converts it into acyclovir, which produces the antiviral effect.
Valacyclovir has better oral absorption than acyclovir, which allows it to be taken less often for many indications.
