What Is Acyclovir Used For?
Uses, Side Effects, Safety

Written by Kathleen Morrison
Medically Reviewed by Dr. Shannon Chatham, DO, a healthcare provider affiliated with Wisp

Key takeaways

• Acyclovir is a prescription antiviral medicine used to treat infections caused by herpes simplex virus (HSV-1 and HSV-2).
• It is also used to treat herpes zoster (shingles) and may be used for chickenpox in certain cases by in-person providers.
• Acyclovir will not cure herpes infections, but it may help sores heal faster, ease discomfort, and manage how often outbreaks happen when taken daily.
• Acyclovir is available as oral tablets and as a topical cream for cold sores. Dosage is personalized by your provider based on your health history and whether you need episodic or suppressive treatment.
• Starting treatment with Acyclovir at the first sign of symptoms tends to give the best results.
• Common side effects include nausea, headache, and diarrhea. Serious side effects are uncommon but require immediate, in-person medical attention.

Cold sore tingling at the worst possible time? Genital herpes flare-up making you miserable? You're probably wondering what your options are, and whether Acyclovir is one of them.

Short answer: yes. Acyclovir is a prescription antiviral medicine for herpes used to treat viral infections caused by the herpes virus family, including cold sores and genital herpes. It's also sometimes used to treat shingles and chickenpox by in-person providers.

Acyclovir works by slowing the growth and spread of herpes in your body, which can help manage symptoms and reduce outbreak frequency.

Let's get into the details so you know exactly what to expect.

Wisp treatment options are available only after consultation with a licensed medical provider, if medically appropriate. You should consult with your healthcare provider before starting a new supplement or treatment regimen. Individual results may vary. Must be 18 or older. For medication details and risks, see site for details.

What is Acyclovir used for?

Acyclovir is used to treat infections caused by specific strains of the herpes virus. It doesn't cure herpes infections—no antiviral does—but Acyclovir works by slowing how the virus copies itself in your body, which can help shorten outbreaks and make them less intense.

For cold sores and genital herpes, Acyclovir is available as oral tablets. For cold sores, a Topical Acyclovir Cream is an option as well.

Your provider will determine the right dosage for your situation, whether that's episodic treatment for active outbreaks or daily suppressive therapy to keep things quieter long-term.

Cold sores

Cold sores are sores that typically appear on or around the lips and are most often caused by HSV-1. However, HSV-2 can also cause cold sores.

Common cold sore symptoms include:

• Tingling, itching, or burning sensation on or near the lips before a sore appears
• Fluid-filled blisters on or around the lips, mouth, or nose
• Pain or soreness around the affected area
• Blisters that break open, ooze, and crust over
• Swollen, red gums (more common during a first outbreak)

Starting treatment at the first sign (that telltale tingle or itch) gives it the best shot at cutting the outbreak short.

How much Acyclovir to take for a cold sore depends on your specific prescription. Dosing is personalized based on your health history, outbreak frequency, etc. Your provider will set the right dosing schedule for you.

Genital herpes

Genital herpes refers to herpes infections that cause sores or other symptoms in or around the genitals, buttocks, or thighs. It can be caused by either HSV-1 or HSV-2.

HSV-2 is more commonly associated with genital herpes, but HSV-1 can also cause genital infections, particularly through sexual contact involving oral herpes.

Common genital herpes symptoms include:

• Small, blister-like bumps that appear in clusters around the genitals, buttocks, or thighs
• Blisters that break open and become painful ulcers or sores
• Itching, tingling, or burning in the genital area before sores appear
• Pain or discomfort during urination
• Flu-like symptoms during a first outbreak (fever, body aches, swollen lymph nodes)

Acyclovir is one of the primary prescription antivirals used for the treatment of genital herpes caused by herpes simplex.

You can take Acyclovir during an active outbreak to help manage pain and speed healing, or take it daily as suppressive therapy to manage how often outbreaks occur.

Dosage for genital herpes is personalized. Your provider will determine the right dose based on whether you need an episodic or suppressive treatment plan, your outbreak history, and your overall health.

One important thing: Taking Acyclovir does not eliminate the risk of passing genital herpes to a sexual partner. You can still spread genital herpes through viral shedding even without visible sores.

Using barriers and having honest conversations with your partner are still key. Avoid sexual contact during active outbreaks or at the first symptoms.

Other conditions treated with Acyclovir by in-person providers

Beyond cold sores and genital herpes, Acyclovir is also used to treat other herpes virus infections. These conditions are managed by in-person providers:

Shingles (herpes zoster)

Shingles is caused by the varicella-zoster virus—the same one responsible for chickenpox. Acyclovir can be used to treat shingles outbreaks.

In-person providers will determine the appropriate dose, which is typically higher than what's used for herpes simplex infections. If you suspect shingles, see an in-person provider promptly.

Chickenpox

Acyclovir is sometimes prescribed for chickenpox, particularly in adolescents, adults, or people at higher risk of complications.

It's not routinely a first-line treatment for healthy young children. Talk with your in-person provider about whether Acyclovir is appropriate for your specific situation.

How to take Acyclovir safely

Take Acyclovir exactly as prescribed; that means following your dosing schedule, not skipping doses, and finishing the full course even if symptoms clear up sooner. (Your virus didn't get the memo that you're feeling better.)

Drink plenty of water while taking this medication. Acyclovir is processed through the kidneys, and staying well-hydrated helps your body handle it properly.

If you miss a dose, take it as soon as you remember, unless it's almost time for your next dose.

In that case, skip the missed dose and continue as normal. Don't double up. And if you take too much, call your poison control center at 1-800-222-1222 or seek emergency, in-person medical advice right away.

How long does it take for Acyclovir to work?

How long it takes for Acyclovir to work varies from person to person. Many people notice symptom improvement within a few days of starting treatment with Acyclovir, though full healing can take longer depending on the outbreak's severity and your individual response.

Acyclovir works best when you start taking this medication at the very first sign of an outbreak.

For recurrent herpes, having your prescription on hand so you can start right away can make a real difference. The sooner you begin, the shorter and less intense the outbreak tends to be.

Possible side effects of Acyclovir

Like any medicine, Acyclovir may cause side effects. Most people tolerate it well, but knowing what to watch for helps you feel prepared.

Possible side effects of Acyclovir Tablets

Common side effects of Acyclovir Tablets may include:

• Nausea or vomiting
• Diarrhea
• Headache
• Fatigue or unusual tiredness or weakness
• Dizziness
• Stomach pain

Serious side effects that require immediate, in-person medical attention:

• Easy bruising or bleeding, purple or red spots on the skin, pale skin
• Changes in behavior, confusion, or hallucinations
• Signs of kidney problems: little or no urinating, painful or difficult urination, swelling in your feet or ankles
• Seizures, severe skin reaction, and thrombotic thrombocytopenic purpura / hemolytic uremic syndrome in immunocompromised patients

This is not a complete list of risks and side effects, and others may occur. If symptoms worsen or you notice signs of an allergic reaction, contact a provider right away.

Possible side effects of Acyclovir Topical Cream

Common side effects of Acyclovir Cream may include:

• Dry, cracked, or peeling lips
• Dryness or flaking of treated skin
• Burning, stinging, or itching when the medicine is applied

Serious side effects that require immediate attention:

• Signs of an allergic reaction: hives; trouble breathing; swelling of the face, lips, tongue, or throat

This is not a complete list of risks and side effects, and others may occur. If symptoms worsen, contact a provider right away.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch or call 1-800-FDA-1088.

Talk to a provider

A quick chat with a provider can help you sort through these questions and land on a plan that actually works for you. Whether it’s an in-person visit or a virtual consult, having expert guidance makes it easier to find the best option for your body, lifestyle, and needs.

Precautions and interactions

Before you start, tell your health care professional about your full medical history and all the medicines you take, including prescription, nonprescription, vitamins, and supplements.

You should not use Acyclovir if you are allergic to Acyclovir or Valacyclovir.

If you have kidney problems or reduced kidney function, tell your provider before starting; your dose may need adjustment. Acyclovir can interact with other medicines, especially those that affect kidney function. Tell your provider and pharmacist about every medicine you're currently taking.

This is not a complete list of potential drug interactions. You should disclose all current, recent, and ongoing medications, including prescription drugs, to your healthcare provider for a comprehensive interaction assessment.

Acyclovir vs. Valacyclovir: Which one's for you?

You'll hear these two names tossed around together a lot. Acyclovir and valacyclovir are both prescription antivirals used to treat viral infections caused by herpes simplex, and people often wonder which one they should be taking.

Here's the deal: Valacyclovir actually converts to Acyclovir in your body. So they're closely related, not competitors.

The main practical difference? Dosing. Acyclovir is typically taken more frequently throughout the day, while Valacyclovir requires fewer daily doses because it's absorbed more efficiently. Your provider determines the schedule that fits your situation

Both are well-established medicines for managing herpes, and the right choice depends on your lifestyle, your outbreak patterns, and what your provider recommends.

When to loop in a provider

Most people take Acyclovir without serious issues, but there are times you should reach out. Here are signs it's time to talk to a provider about your prescription treatment for herpes:

• Your symptoms don't improve after a few days of treatment with Acyclovir
• You're experiencing frequent or worsening outbreaks despite taking your medicine
• You want to discuss switching between episodic and suppressive therapy
• You're noticing new or unusual symptoms during a herpes infection
  

When to call your in-person provider right away

Some situations need urgent, in-person attention. Call your in-person provider or seek emergency care if:

• You notice signs of an allergic reaction (rash, swelling, trouble breathing)
• You're urinating significantly less than usual or have signs of kidney problems
• You feel confused, agitated, or unlike yourself
• You develop severe stomach pain, pale skin, unusual bruising, or spots on the skin
• You experience any serious side effects listed above

Don't wait and see if something feels seriously wrong. Getting medical advice early is always the better call.

Get herpes care without the in-person waiting room

Whether it's a cold sore that showed up uninvited or a genital herpes flare-up, you deserve care that's fast, private, and completely judgment-free.

Wisp makes it easy to get the treatment you need. With prescription antivirals for both outbreak and suppressive treatment and targeted Acyclovir Cream for cold sores, you can take charge of your herpes care from wherever you are.

Complete a quick online consultation with a licensed provider, and if medically appropriate, your prescription gets sent to your local pharmacy or delivered free in discreet packaging.

Because the only thing that should be spreading is confidence.

Most prescriptions are sent to your pharmacy within 3 hours of completing your patient intake form and secure chat or video call when necessary. Pending retail pharmacy hours.

This blog post is for informational and educational purposes only and should not be taken as professional advice. Always consult with a qualified professional before making any decisions based on the information provided here.