Valacyclovir for shingles: how effective is it?

Mike Bohl, MD, MPH, ALM - Contributor Avatar

Written by Chimene Richa, MD 

Mike Bohl, MD, MPH, ALM - Contributor Avatar

Written by Chimene Richa, MD 

last updated: Jun 30, 2020

4 min read

What is herpes zoster (shingles)?

Shingles, also called herpes zoster, is caused by the varicella-zoster virus (VZV). This virus causes both chickenpox (varicella) and shingles (herpes zoster). Shingles occur when VZV is reactivated later on in life. According to the Centers for Disease Control and Prevention (CDC), approximately 1 in 3 people in the United States will develop shingles at some point (CDC, 2019).

If you have had chickenpox in the past, then you are at risk of getting herpes zoster. After recovering from chickenpox, VZV seems to disappear, but it actually goes into hiding in your nervous system—waiting to come back with a vengeance. Over 99% of Americans born before 1980 have had chickenpox and are, therefore, at risk of developing shingles (CDC, 2019). Reactivation of VZV typically happens to older adults (most commonly over 60 years of age) or during periods of low immune system health (HIV, illness, cancer treatments, stress, etc.).

Shingles symptoms typically begin with itching, tingling, or burning in an area on one side of the body. One or two days later, a painful, burning rash made up of small fluid-filled blisters (like chickenpox) develops in that area. Herpes zoster usually only affects the area fed by a specific nerve (whichever nerve is hiding the virus), and this area is called a dermatome. New blisters will keep popping up in the next three to five days before crusting and eventually healing over the following two to four weeks. Other symptoms can include fever, headache, chills, and upset stomach. Unfortunately, 10–15% of people will have nerve pain that lasts for months to years after the rash has disappeared. This is called post-herpetic neuralgia, and it is the most common complication from herpes zoster (Albrecht, 2019).

Shingles, like other herpes viruses, is a lifelong infection and there is no cure. However, treatments like antivirals can decrease both the length and severity of your outbreak. Antivirals are most effective if started as soon as possible and include medications such as acyclovir, valacyclovir, and famciclovir.


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What is valacyclovir?

Valacyclovir (brand name Valtrex) is an antiviral drug that works against herpes infections like genital herpes (herpes simplex virus 2), cold sores (herpes simplex virus 1), chickenpox (VZV), and shingles (VZV). Antivirals work by making it harder for viruses to copy themselves and spread from cell to cell (Ormrod, 2000).

Valacyclovir is a prescription drug that you take by mouth as soon as possible after developing the virus. It is important to know that valacyclovir does not cure the virus forever—it only treats the current episode, making it less painful and resolve faster than it would without medication. Also, valacyclovir can be used long term (suppressive therapy) to prevent or suppress outbreaks.

Can valacyclovir treat shingles?

Yes. Valacyclovir is an FDA-approved treatment for herpes zoster (as well as genital herpes and cold sores). It decreases the duration and severity of symptoms (FDA, 2008). It should be started as soon as possible after the rash starts. You will get the best response if you take the medication within 72 hours of the rash appearing (Ormrod, 2000).

Data shows that even if valacyclovir is started more than 72 hours after a rash's appearance, there can still be some benefit (Ormrod, 2000). Sometimes, depending on your pain level, your healthcare provider may recommend pain medication or over-the-counter remedies (calamine lotion, oatmeal baths, etc.) along with valacyclovir. As with other herpes viruses, valacyclovir does not cure shingles—it can make your current episode less painful and resolve faster if started right away.

Is valacyclovir safe?

Valacyclovir is generally well tolerated. However, like all drugs, valacyclovir does have side effects. The most common side effects of valacyclovir include headache, nausea, abdominal pain, tiredness, depression, and skin rash (UpToDate, n.d.). Let your healthcare provider know if you experience any of these symptoms, especially if they are severe or do not improve.

Serious side effects can occur, especially in the elderly, people with kidney problems, or those with weakened immune systems. Elderly people who use this medication are at a higher risk of central nervous system side effects like agitation, hallucinations, confusion, etc. (UpToDate, n.d.). Also, people with kidney problems (renal disease) are more likely to have side effects from taking valacyclovir, and some may even experience renal failure.

Immunocompromised people, like those with HIV/AIDS, may develop a blood disorder called thrombotic microangiopathy that affects their red blood cells and platelets. Valacyclovir is classified as Pregnancy Category B by the FDA—this means that there are no adequate and well-controlled studies of valacyclovir use in pregnant women. Therefore, valacyclovir should be used in pregnancy only if the potential benefit justifies the potential risk to the fetus. Breastfeeding women should also be careful when taking valacyclovir and should seek medical advice before starting this drug (FDA, 2008).

Valacyclovir can interact with other medications that you may be taking, like cladribine or foscarnet. You should avoid taking valacyclovir if you are currently on those medications. Talk to your healthcare provider about any other potential drug interaction before starting valacyclovir. Valacyclovir may also interfere with the effectiveness of the varicella or zoster virus vaccine. You should avoid taking valacyclovir 24 hours prior and 14 days after getting the vaccines. Be sure to tell your healthcare provider about any other medical problems you may have or medications that you are taking prior to starting valacyclovir.


If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

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Current version

June 30, 2020

Written by

Chimene Richa, MD

Fact checked by

Mike Bohl, MD, MPH, ALM

About the medical reviewer

Dr. Mike is a licensed physician and a former Director, Medical Content & Education at Ro.