Acyclovir, famciclovir, and valacyclovir are antiviral
medicines used to treat
genital herpes. All are effective. But because
valacyclovir and famciclovir are absorbed better by the stomach, they can be
taken less often than acyclovir. Antiviral medicines are usually taken by mouth
(orally). But they are sometimes given
intravenously (IV) in severe genital herpes outbreaks
or herpes in newborns.
The topical form of acyclovir (Zovirax
ointment) offers little benefit in the treatment of genital herpes and is not
Antiviral medicines stop the growth of the
herpes simplex virus (HSV).
Antiviral medicines may be given
Antiviral medicines may
significantly reduce the severity of an outbreak of genital herpes and decrease
the time it takes an outbreak to heal. The medicine also decreases the number
of days of painful symptoms. And for some people, this medicine decreases the
number of days you can spread the virus.
The amount and how often you take antivirals depends on the specific
antiviral and whether you are taking them for a primary outbreak, recurrent
outbreak, or for suppressive therapy.
Antiviral medicine is most
effective if you take it when you first notice the prodromal symptoms (tingling
and pain) of a recurrent genital herpes outbreak and if you take it for the
next 5 to 7 days or until symptoms go away.
Some people with
frequent recurrent outbreaks (more than 6 a year) take antiviral
medicine every day (suppressive therapy) to help reduce the frequency and
duration of the outbreaks. Antiviral medicine can reduce the number of
outbreaks by 70% to 80%.1
that an HSV-infected person in a heterosexual, single-partner (monogamous)
relationship who takes valacyclovir daily in the doses used for suppressive
therapy to prevent recurrent outbreaks reduces the risk of infecting his or her
partner.2 Other antiviral medicines may also reduce
transmission, but further study is needed.
The CDC has published
guidelines about the use of antiviral medicines in pregnancy.1
If a genital herpes blister or sore is present at the
time of labor and delivery, a
cesarean section is usually done. A cesarean section
may be recommended if a woman suspects she has symptoms of an impending
outbreak, such as tingling or pain (prodromal symptoms). For women who have
recurrent outbreaks, acyclovir used in the last 4 weeks of pregnancy may reduce
the need for a cesarean section by reducing the risk of an outbreak at the time
human immunodeficiency virus (HIV) should talk with
their doctors for advice about these medicines. Depending on the stage of their
illness, they may need higher doses or longer treatment time with antiviral
All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.
Here are some important things to think about:
or other emergency services right away if you have:
Call your doctor right away if you have:
Common side effects of this medicine include:
See Drug Reference for a full list of side effects. (Drug
Reference is not available in all systems.)
Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.
There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.
If you are pregnant, breast-feeding, or planning to get pregnant, do not use any medicines unless your doctor tells you to. Some medicines can harm your baby. This includes prescription and over-the-counter medicines, vitamins, herbs, and supplements. And make sure that all your doctors know that you are pregnant, breast-feeding, or planning to get pregnant.
Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.
Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.
Centers for Disease Control and Prevention (2010). Genital HSV infections section of Sexually transmitted diseases treatment guidelines, 2010. MMWR, 59(RR-12): 20–25. Also available online: http://www.cdc.gov/std/treatment/2010/default.htm.
Hollier LM, Straub H (2011). Genital herpes, search date January 2010. BMJ Clinical Evidence. Available online: http://www.clinicalevidence.com.
December 20, 2012
Sarah Marshall, MD - Family Medicine
& Jeanne Marrazzo, MD, MPH - Infectious Disease
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