Acyclovir medication against a pink background

What Is Acyclovir?

Written on August 22, 2023 Gillian (Gigi) Singer, MPH, Sexuality Educator & Certified Sexologist. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

Table of contents

What Is Acyclovir?

Acyclovir is a medication that functions as an antiviral. Antiviral medications aid your immune system by fighting against infections and keeping viruses from multiplying in the body, lowering the overall amount of virus throughout the body.

This medication can come in the form of oral tablets, capsules, creams, ointments, and/or intravenous (IV) formulations. The specific dosage and duration of treatment depend on the type of infection being treated and the individual's medical condition.

Uses of Acyclovir

Antiviral acyclovir is used to treat a variety of viral infections. Acyclovir is commonly prescribed to treat conditions such as those below.

Herpes Simplex Infections (HSV)

This medication is employed to treat genital herpes, cold sores (or oral herpes), and other HSV infections.

Herpes simplex virus “is a common infection that can cause painful blisters or ulcers. It primarily spreads by skin-to-skin contact” that is treatable but not curable.[1] It is viral, so once it is contracted, it remains in the body of the host.

The World Health Organization estimates that 3.7 billion people under 50 years old in the world have herpes simplex virus type 1 (HSV-1) infection, which is the main cause of oral herpes. About 491 million people between the ages of 15 and 49 have herpes simplex virus type 2 (HSV-2) infection which is the main cause of genital herpes. Most HSV infections are asymptomatic, though some infections result in painful blisters or ulcers that can be recurring.[1]

Chickenpox (varicella-zoster virus, or VZV)

This medication can be used to treat chickenpox in both children and adults alike.

Chickenpox is an extremely contagious airborne virus that causes an incredibly itchy rash on the chest, back, face, or whole body. It’s estimated that greater than 95% of American adults have had chickenpox and more than 4 million people get chickenpox every year, though that number has decreased since the vaccine was introduced in 1995.[2]

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Shingles (varicella-zoster virus, or VZV)

It is also effective in treating shingles, a painful rash caused by the reactivation of the varicella-zoster virus in individuals who have previously had chickenpox.

Shingles is “a painful, usually itchy, rash that develops on one side of the face or body. The rash consists of blisters that typically scab over in 7 to 10 days and fully clear up within 2 to 4 weeks.”[3]

The CDC reports, “About 1 out of every 3 people in the United States will develop shingles, also known as herpes zoster, in their lifetime. An estimated 1 million people get shingles each year in this country. If you’ve ever had chickenpox, you can get shingles. Even children can get shingles. Your risk of shingles increases as you get older.”[3]

Herpes encephalitis (herpes meningoencephalitis)

This is a very rare but serious viral infection of the brain caused by herpes simplex virus. Acyclovir can be used as a treatment for herpes encephalitis.

According to Johns Hopkins, “Encephalitis is caused by the herpes simplex virus. Most are caused by herpes simplex virus type 1 (HSV1), the virus that also causes cold sores. The disease may also be caused by herpes virus type 2 (HSV2).”[4]

Acyclovir as prophylaxis

Acyclovir may be prescribed to individuals with weakened immune systems to prevent recurrent herpes simplex or shingles infections. It can actually be effective as a treatment and prophylaxis for those who are and are not immunocompromised.[5]

Getting Care with Everlywell

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With telehealth from Everlywell, you are just three simple steps away from relief:

  1. Create your profile online, fill out your medical history, and check to see if your insurance is accepted.
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Receive a care plan to address your needs and symptoms, which may include testing, prescriptions, and lifestyle recommendations.

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  1. Herpes simplex virus. World Health Organization. Accessed August 16, 2023.
  2. Chickenpox. Boston Children’s Hospital. Accessed August 16, 2023.
  3. Signs and symptoms of shingles (herpes zoster). Centers for Disease Control and Prevention. . May 10, 2023. Accessed August 16, 2023.
  4. Herpes meningoencephalitis. JHM. November 19, 2019. Accessed August 16, 2023.
  5. Gold D, Corey L. Acyclovir prophylaxis for herpes simplex virus infection. Antimicrob Agents Chemother. 1987;31(3):361-367. doi:10.1128/AAC.31.3.361
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