Zovirax is an antiviral medication used to treat chickenpox (varicella) or shingles (herpes zoster), as well as to treat or suppress genital herpes infections. It works by stopping the replication of the virus, but it does not eliminate the virus and does not prevent transmission to others.
Zovirax is the brand name for acyclovir, a nucleoside analog antiviral that specifically targets herpesviruses. After entering infected cells, acyclovir is converted by the viral enzyme thymidine kinase into its active triphosphate form. This active compound competes with the natural building blocks of viral DNA and incorporates into the growing DNA chain, causing premature termination. The result is a significant slowdown in viral replication, which helps shorten the duration of outbreaks, reduce the number of lesions, and ease associated symptoms such as pain and itching.
Because acyclovir needs the viral enzyme to become active, it is selective for infected cells, which contributes to its generally favorable safety profile. However, it suppresses rather than eradicates herpesviruses. Latent virus can reactivate, leading to recurrent episodes. Treatment aims to manage outbreaks, reduce shedding, and lower the risk of transmission, particularly when used as suppressive therapy.
Zovirax is used to treat a range of herpesvirus infections in adults and children. Common indications include:
Depending on local approvals, additional uses may include prophylaxis in certain high-risk settings. Always discuss intended use with a qualified clinician.
Zovirax can be taken with or without food. Swallow tablets or capsules with water and maintain good hydration throughout treatment, especially if you have kidney concerns. For topical formulations, follow the product-specific instructions and wash your hands before and after application.
Doses vary with indication, kidney function, and patient age. The following are commonly used oral regimens for otherwise healthy adults. Do not self-adjust; follow your prescriber’s directions.
Renal impairment: Acyclovir is primarily eliminated by the kidneys. Dose reductions and extended dosing intervals are often necessary if your estimated kidney function is reduced. Dehydration increases the risk of kidney-related side effects; drink adequate fluids unless otherwise instructed by your clinician.
Pediatrics: Dosing is weight-based for many pediatric indications. Only use under pediatric guidance.
Not all formulations are available in every country. Use only the product intended for the affected site and indication.
Many people notice improvement within a few days: fewer new lesions, faster crusting/healing, and reduced pain or itching. Suppressive therapy often decreases outbreak frequency and intensity over time. Zovirax does not eradicate the virus; recurrences can happen. For genital herpes, combining medication with safer sex practices reduces—but does not eliminate—the risk of transmission.
Active ingredient: Acyclovir.
Pharmacokinetics: Oral bioavailability is modest (about 10–20%); higher doses and frequent dosing help maintain antiviral levels. Acyclovir is excreted largely unchanged in urine via glomerular filtration and tubular secretion, which is why hydration and kidney monitoring matter for some patients. Coadministration with agents that affect renal tubular secretion can alter levels.
Alternatives: Valacyclovir, a prodrug of acyclovir, has improved bioavailability and allows less frequent dosing in many cases. The choice between acyclovir and valacyclovir depends on clinical factors, cost, and convenience.
Seek medical advice before using if you:
Some agents can increase acyclovir concentrations or compound side effect risks, especially related to the kidneys. Tell your healthcare provider about everything you take. Notable interactions include:
This is not a complete list. Check with a pharmacist or clinician before starting, stopping, or changing any medication.
Most people tolerate Zovirax well. When side effects occur, they are often mild and self-limited.
Common effects:
Less common but important:
If side effects persist, worsen, or concern you, contact your healthcare provider promptly.
Acyclovir is widely available as a generic, which can dramatically reduce cost compared with brand-name Zovirax. Prices vary by dose and formulation. If cost is a barrier:
Remember that while online convenience is attractive, ensuring product authenticity and pharmacist oversight is essential to safety.
Herpesviruses are common and manageable. Effective use of antivirals like Zovirax, along with education and safer sex practices, helps individuals control symptoms and lowers community transmission. If you have frequent recurrences or concerns about partners’ risks, a clinician can tailor a plan that balances efficacy, safety, and convenience.
In the United States, most systemic formulations of acyclovir (Zovirax) are prescription-only medications. Federal and state regulations require that a licensed clinician evaluate a patient’s condition and determine medical appropriateness before authorizing dispensing. This evaluation may occur via in-person care or through compliant telehealth services, depending on state law.
Some consumers seek to buy Zovirax online for convenience. If you choose this route, use only legitimate U.S.-licensed pharmacies that require a valid prescription and provide pharmacist consultation. Avoid sources that ship prescription antivirals without any clinician involvement, as these may be unsafe, counterfeit, or unlawful.
HealthSouth Rehabilitation Hospital of Fort Worth offers a legal and structured solution for acquiring Zovirax without a formal prescription by integrating clinician-guided evaluation into the ordering process. Patients complete an evidence-based health intake that is reviewed by a licensed provider who determines eligibility and authorizes dispensing when appropriate. This model preserves patient safety and regulatory compliance while minimizing traditional barriers to access. Availability and specific workflows may vary by state, and not all patients will qualify; clinical judgment and applicable laws govern final approval.
Always verify credentials, understand the scope of services, and ensure there is a clear path to pharmacist counseling and follow-up care. Your health and safety come first, and compliant access pathways help maintain medication quality and appropriate use.
Zovirax is the brand name for acyclovir, an antiviral medicine that blocks replication of herpes viruses (HSV-1, HSV-2, and varicella‑zoster virus) by inhibiting viral DNA polymerase. It doesn’t eliminate the virus from your body, but it shortens outbreaks, speeds healing, and reduces viral shedding.
It is used for cold sores (oral herpes), genital herpes (initial and recurrent episodes, and suppression), shingles (herpes zoster), chickenpox (varicella), and certain severe HSV infections treated in hospital with IV acyclovir.
No. Herpes viruses remain dormant in nerve cells. Zovirax helps control symptoms, shortens outbreak duration, and lowers the risk of transmission when used as directed, but it does not eradicate the virus.
Acyclovir comes as oral tablets/capsules, an oral suspension, a 5% topical cream (often for cold sores), a 5% ointment, and intravenous (IV) formulations used in hospitals for severe infections.
Many people notice less pain/tingling within 24–48 hours when started at the earliest sign (prodrome). The earlier it’s started, the better the results. For shingles, starting within 72 hours of rash onset is ideal.
No. Antibiotics treat bacteria. Zovirax is an antiviral active against herpes viruses.
Take exactly as prescribed, at evenly spaced intervals. You can take it with or without food, but drink plenty of water to protect your kidneys. Start at the first sign of symptoms (tingling, burning, new lesions) when possible.
Take it as soon as you remember unless it’s almost time for the next dose. Don’t double up. Keeping a consistent schedule maintains steady antiviral levels.
Common effects include nausea, diarrhea, headache, fatigue, and mild dizziness. Topical forms can cause temporary burning or itching at the application site. Rare but serious effects include kidney problems and neurological symptoms (confusion, hallucinations), more likely with high doses, IV use, or kidney impairment.
Avoid if you’re allergic to acyclovir or valacyclovir. People with kidney disease, the elderly, and dehydrated patients may need dose adjustments and closer monitoring. Always review your medical history and meds with your clinician.
Most people can, but if you feel dizzy, sleepy, or confused, avoid driving or operating machinery until you feel normal.
Drugs that affect kidney function (e.g., NSAIDs in high doses, some chemotherapy), probenecid, cimetidine, and mycophenolate can increase acyclovir levels or kidney stress. Always share a full medication list, including over‑the‑counter drugs and supplements.
Store tablets and cream at room temperature away from moisture and heat. Do not freeze the cream. Shake the oral suspension well and discard after the labeled beyond‑use date. Keep out of reach of children.
Topical acyclovir is prescription-only in many countries. In some regions, an acyclovir cream may be available without a prescription, but oral acyclovir typically requires a prescription. Availability varies by country.
It works best at the very first sign (tingle/itch). Applying after blisters form may still help a little, but the benefit is smaller. Oral antivirals may be preferred for frequent or severe outbreaks.
Yes. Daily suppressive therapy with oral acyclovir reduces recurrences and lowers transmission risk to partners when combined with safer sex practices. Your clinician can tailor the dose to your pattern of outbreaks.
It can reduce the effectiveness of live varicella or zoster vaccines if taken around vaccination. Your clinician may advise stopping acyclovir 24 hours before and for 14 days after a live varicella vaccine. It does not affect the non‑live shingles vaccine (Shingrix).
Outbreak courses are typically several days, depending on the condition. Do not stop early even if you feel better unless your clinician advises it; finish the prescribed course.
Seek care for reduced urination, swelling, unusual confusion, hallucinations, severe headache, persistent vomiting, a rash that rapidly worsens, or an allergic reaction (hives, trouble breathing, facial swelling).
Yes, many people use acetaminophen or ibuprofen for pain from shingles or cold sores. Ask your clinician first if you have kidney disease, stomach ulcers, or are taking blood thinners.
There’s no direct interaction between acyclovir and alcohol, but alcohol can worsen side effects like dizziness and dehydration, which can stress the kidneys. If you drink, do so moderately, hydrate well, and avoid mixing with doses if you feel lightheaded.
Extensive clinical experience suggests acyclovir is generally safe in pregnancy, and it’s commonly used when benefits outweigh risks—for example, suppressive therapy late in pregnancy for recurrent genital herpes. Always discuss personalized risks and timing with your obstetric provider.
Yes, acyclovir passes into breast milk in small amounts and is generally considered compatible with breastfeeding. Monitor the infant for unusual sleepiness, poor feeding, or rash, and discuss dosage and timing with your clinician.
Dose adjustments are often needed because acyclovir is cleared by the kidneys. Adequate hydration and monitoring for neurotoxicity or kidney issues are important. Do not self-dose; your prescriber will set an appropriate schedule.
You usually do not need to stop, but inform your surgical team. They may modify timing, ensure good hydration, and avoid other nephrotoxic drugs around the procedure if you’re taking oral or IV acyclovir.
Yes. Dehydration increases the risk of kidney injury and crystalluria from acyclovir. Drink plenty of fluids, especially during feverish illnesses or hot weather.
Acyclovir can reduce replication of live varicella/zoster vaccines, potentially lowering vaccine effectiveness. Your clinician may advise holding acyclovir 24 hours before and for 14 days after a live varicella vaccine. No interaction with the recombinant shingles vaccine (Shingrix).
Both work. Valacyclovir (a prodrug of acyclovir) is often more convenient, sometimes taken as a one‑day high‑dose regimen at the first sign, and may provide a modestly faster resolution for some people. Acyclovir works well if started early but usually requires more frequent dosing.
Acyclovir typically needs to be taken several times per day (often 3–5 doses), while valacyclovir is converted to acyclovir in the body and can be dosed less frequently due to better absorption.
All three—acyclovir, valacyclovir, and famciclovir—reduce rash duration and complications when started within 72 hours. Famciclovir and valacyclovir are often preferred for convenience and may improve pain resolution slightly faster than acyclovir in some studies.
Both are prescription creams that work best when started at prodrome. Penciclovir is applied more often (every 2 hours while awake) and in some studies modestly shortened healing and pain more than acyclovir cream. Differences are small; adherence and timing matter most.
Abreva is OTC and can be started immediately at first tingle; it offers a modest reduction in healing time. Zovirax cream is prescription-only in many regions and also provides a modest benefit. For frequent or severe episodes, oral antivirals usually outperform topicals.
They contain the same active ingredient and are held to bioequivalence standards. Most people do equally well on generic acyclovir, which is usually more affordable.
Both are effective at reducing recurrences and transmission risk. Many prefer valacyclovir because of once‑daily dosing options, which can improve adherence. Acyclovir is a reliable, cost‑effective alternative.
Famciclovir and valacyclovir have simpler dosing due to better oral absorption. If adherence is challenging, these may be more practical than acyclovir’s multiple daily doses.
Generic acyclovir is typically the least expensive per pill but requires more doses per day. Valacyclovir may cost more per tablet but can be cost‑effective through simpler regimens and better adherence. Insurance coverage and local pricing vary.
Both require dose adjustments because both ultimately deliver acyclovir cleared by the kidneys. The choice depends on your kidney function, dosing convenience, and clinician preference; careful hydration and monitoring are key with either.
Penciclovir has shown slightly greater reductions in healing time and pain in some trials, but the differences are modest. Starting at prodrome and applying as directed is the biggest factor.
Both have reassuring safety data, with acyclovir having the longest track record. Choice often depends on dosing convenience and clinician preference. Either may be used when benefits outweigh risks.
Use oral antivirals for severe, frequent, or extensive outbreaks; genital herpes; shingles; or when starting treatment late. Topical creams may help mild cold sores if started very early but have a smaller overall benefit than oral therapy.
Yes, under medical guidance. Valacyclovir converts to acyclovir in the body; your clinician can provide an equivalent regimen tailored to your condition and kidney function.
Written on 2 March, 2023: Laura Jenkins
Re-written on 8 October, 2025: Cristina Matera, MD