acyclovir
Acyclovir (Zovirax) is an antiviral medication used for the treatment of shingles, chickenpox, and herpes simplex virus infections (e.g., cold sores, genital herpes). It comes in many different forms, including oral pills that are usually taken 4 to 5 times a day, as well as topical cream or ointment that are typically applied 5 to 6 times a day. Some of the most common side effects include nausea, vomiting, and diarrhea (for oral forms), and skin irritation (for topical forms). Acyclovir (Zovirax) is prescription only and not available over the counter.
What is Acyclovir (Zovirax)?
What is Acyclovir (Zovirax) used for?
Oral capsule, tablet, and suspension:
Genital herpes
Shingles (herpes zoster)
Chickenpox (varicella) in people 2 years and older
Buccal tablet (Sitavig):
Cold sores (herpes labialis) that keep coming back in adults
Ointment:
Genital herpes in adults
HSV infections in adults with a weakened immune system
Cream
Cold sores (herpes labialis) that keep coming back in people 12 years and older
How Acyclovir (Zovirax) works
Acyclovir (Zovirax) is an antiviral medication that stops a protein (an enzyme called DNA polymerase) in the herpes simplex virus (HSV) and varicella-zoster virus (VZV). Without this enzyme, the virus can't make copies of itself.
Drug Facts
More on Acyclovir (Zovirax) essentials
Get your GoodRx coupon
What are the side effects of Acyclovir (Zovirax)?
Common Side Effects
- Feeling unwell (up to 12%)
- Nausea and/or vomiting (up to 5%)
- Diarrhea (up to 3%)
- Headache (up to 2%)
- Headache (3%)
- Dizziness (1%)
- Low energy (1%)
- Pain at application site (1%)
- Irritation at application site (1%)
- Redness (1%)
- Rash (1%)
- Application site reaction (5%)
- Burning and stinging at application site (30%)
Source: DailyMed
The following side effects have also been reported
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
More common
Mild pain, burning, or stinging
Less common
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Pros and cons of Acyclovir (Zovirax)
Pros
Comes in many different formulations
Can lower your risk of spreading the virus to others
Oral capsules, tablets, and suspension can be taken by children as young as 2 years old for chickenpox
Can shorten how long outbreaks last
Not many interactions with other medications
Cons
Needs to be taken or applied many times a day for treatment
Doesn't cure HSV and VZV infections, only controls the outbreak
Oral forms can cause unpleasant stomach side effects, like nausea and diarrhea
Doesn't completely prevent spreading the virus to others
Not available over the counter
Pharmacist tips for Acyclovir (Zovirax)
If you're taking the acyclovir (Zovirax) oral suspension, shake the bottle well before each dose and only use the measuring device provided by your pharmacist.
The acyclovir (Zovirax) cream should only be applied to the lips and face, and not inside of your mouth or nose. Avoid getting the cream or ointment in your eyes.
If you have repeated herpes outbreaks, it can be helpful to have a acyclovir (Zovirax) prescription ready at the pharmacy or a course of medication at home in case an outbreak happens.
Drink plenty of fluids and stay hydrated while taking acyclovir (Zovirax). This can help prevent potential kidney damage.
Acyclovir (Zovirax) needs to be taken many times a day for treatment, which can be difficult. Setting an alarm on your phone or setting up a pill box can help you remember to take all your doses.
Acyclovir (Zovirax) isn't a cure for genital herpes, but it'll help control infection breakouts and shorten healing time. Avoid sexual contact while you are having an outbreak and continue to follow safe sex practices (like using condoms).
Additional tips for acyclovir (Zovirax) buccal tablet (Sitavig):
Acyclovir (Sitavig) buccal tablets work best when used within 1 hour of initial cold sore symptoms and before any lesions appear.
Using a dry finger, place the acyclovir (Sitavig) tablet between your cheek and upper gum on the side of your symptoms. Place the rounded side to the gum for comfort.
Hold the acyclovir (Sitavig) tablet in place for 30 seconds so that it sticks. Then, allow it to dissolve during the day. Don't crush, chew, or swallow the tablet, since it's meant to be absorbed through your gum slowly.
Don't chew gum or touch the acyclovir (Sitavig) tablet after placing it to prevent it from falling out of place.
If the acyclovir (Sitavig) tablet falls off within 6 hours, reapply the same tablet. If it doesn't hold, try to apply a new tablet.
While the acyclovir (Sitavig) tablet is in place, you can eat and drink normally. If you accidentally swallow the tablet within the first 6 hours, drink a glass of water and apply a new tablet to your gum. If it's been more than 6 hours, you don't need to reapply the tablet.
Frequently asked questions about Acyclovir (Zovirax)
How to save using GoodRx
What are the risks and warnings for Acyclovir (Zovirax)?
Acyclovir (Zovirax) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Blood disorders
Risk factors: Medical conditions that weaken your immune system
It's rare, but some people have developed a serious blood disorder while taking acyclovir (Zovirax) in clinical studies. This was observed in people who had a weakened immune system. Your provider might order labs to check your blood work while you're taking this medication. Talk to your provider right away if you notice unusual or unexplained fever; bleeding; bruising; confusion; lack of energy; nausea; vomiting; diarrhea; or dark urine.
Kidney problems
Risk factors: Low fluids in the body | Ages 65 years or older | Kidney problems | Using other medications that harm the kidneys
Acyclovir (Zovirax) can cause serious harm to the kidneys, especially in older adults. The dose of the medication should be lowered in people with poor kidney function. The risk is also higher if you become dehydrated or take other medications that can harm the kidney such as NSAIDs like ibuprofen (Advil, Motrin) and naproxen (Aleve). Stay hydrated while taking acyclovir (Zovirax) and talk to your provider before taking any medication, including over-the-counter (OTC) pain and cold medications. Your provider might order lab tests to monitor your kidney health.
Acyclovir (Zovirax) dosage forms
Typical dosing for Acyclovir (Zovirax)
Your dose will depend on the reason you're taking acyclovir (Zovirax). In general:
Oral capsule, tablet, and suspension
Shingles: The typical dose is 800 mg by mouth 5 times a day (about every 4 hours) for 7 to 10 days.
Genital herpes:
Treatment: The typical dose is 200 mg by mouth 5 times a day (about every 4 hours) for 5 to 10 days.
Suppressive/daily therapy: The typical dose is 400 mg by mouth twice a day for up to a year.
Chickenpox:
Children (ages 2 to 18 years old and up to 40 kg): Your child's provider will determine their dose is based on your child's body weight. The typical dose is 20 mg/kg body weight by mouth 4 times a day for 5 days.
Adults and children over 40 kg: The typical dose is 800 mg by mouth 4 times a day for 5 days.
Cold Sores: Place 1 tablet (50 mg) in your mouth between the upper cheek and gum on the same side where the cold sore is located. Let it dissolve slowly throughout the day.
Genital herpes and HSV infections in people with a weakened immune system: Apply to the affected area(s) every 3 hours (6 times per day) for 7 days. Make sure to use enough to cover all lesions (use one-half inch ribbon of medication per 4 square inches of area). It's recommended to use a rubber glove when applying to help prevent spreading the infection.
Cold Sores: Apply to the affected area(s) 5 times a day for 4 days.
Acyclovir (Zovirax) is also available as an intravenous (IV) injection that's given by a trained healthcare provider, typically in a hospital setting.
Please note: Your dose might differ if you have kidney problems.
Interactions between Acyclovir (Zovirax) and other drugs
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
How much does Acyclovir (Zovirax) cost?
Acyclovir (Zovirax) contraindications
Allergy to acyclovir (Zovirax) or valacyclovir (Valtrex)
Allergy to milk protein concentrate (Sitavig only)
What are alternatives to Acyclovir (Zovirax)?
Oral capsule, tablet, and suspension:
Genital herpes
Shingles (herpes zoster)
Chickenpox (varicella) in people 2 years and older
Buccal tablet (Sitavig):
Cold sores (herpes labialis) that keep coming back in adults
Ointment:
Genital herpes in adults
HSV infections in adults with a weakened immune system
Cream
Cold sores (herpes labialis) that keep coming back in people 12 years and older
Cold sores (herpes labialis)
Genital herpes
Shingles (herpes zoster)
Chickenpox (varicella) in children ages 2 to 17 years old
Cold sores in people age 12 years and older
Genital herpes in adults
Shingles (herpes zoster) in adults
What is the latest news about Acyclovir (Zovirax)?
Acyclovir (Zovirax) images
Get savings updates for Acyclovir (Zovirax)
Receive price alerts, news, and other messages from GoodRx about Acyclovir (Zovirax) and other healthcare topics and relevant savings offers.By signing up, I agree to GoodRx's Terms and Privacy Policy, and to receive marketing messages from GoodRx.
References
Best studies we foundBausch Health US, LLC. (2021). ZOVIRAX- acyclovir cream [package insert]. DailyMed.
Bausch Health US, LLC. (2020). ZOVIRAX- acyclovir ointment [package insert]. DailyMed.
Cadila Pharmaceuticals Limited. (2023). ACYCLOVIR capsule [package insert]. DailyMed.
Camber Pharmaceuticals, Inc. (2021). ACYCLOVIR - acyclovir tablet [package insert]. DailyMed.
Camber Pharmaceuticals, Inc. (2022). ACYCLOVIR - acyclovir suspension [package insert]. DailyMed.
Centers for Disease Control and Prevention. (2019). Shingles (herpes zoster).
Centers for Disease Control and Prevention. (2022). Chickenpox (varicella).
Centers for Disease Control and Prevention. (2022). Genital herpes - CDC basic fact sheet.
Dooling, K., et al. (2023). Five things you should know about shingles. Centers for Disease Control and Prevention.
Emmert, D.H. (2000). Treatment of common cutaneous herpes simplex virus infections. American Family Physician.
EPI Health, Inc. (2020). SITAVIG- acyclovir tablet, delayed release [package insert]. DailyMed.
Farméa. (2013). SITAVIG buccal tablets [package insert].
Fresenius Kabi USA, LLC. (2021). ACYCLOVIR - acyclovir sodium injection, solution [package insert]. DailyMed.
Lorenzo, C. S., et al. (2016). Acyclovir crystalluria: A rare secondary effect of a common drug. Pediatrics & Therapeutics.
U.S. Food and Drug Administration. (2021). Don't be tempted to use expired medicines.
World Health Organization. (2023). Herpes simplex virus.
Compare other Shingles, Chickenpox, Herpes, Cold Sores drugs
Browse medications
View AllResearch prescriptions and over-the-counter medications from A to Z, compare drug prices, and start saving.