Acyclovir

Acyclovir is a drug that is used to treat shingles, genital herpes, and chickenpox. These conditions are caused by viruses, and the medication works by preventing the viruses from multiplying. Acyclovir is available in a number of forms, including tablets, capsules, and an oral suspension. Common side effects of the drug include nausea, diarrhea, and headaches.

 

What Is Acyclovir?

Acyclovir (Zovirax®) is a prescription medication used to treat the following conditions:
 
This article focuses on the oral forms of acyclovir.
 
(For information on other forms, click Zovirax Cream or Zovirax Ointment.)
 
(Click What Is Acyclovir Used For? for more information, including possible off-label uses.)
 

Who Makes Acyclovir?

Acyclovir is made by GlaxoSmithKline.
 

How Does Acyclovir Work?

Shingles, genital herpes, and chickenpox are caused by viruses. Once a person has been infected with one of these viruses, it never goes away. It remains inactive in certain nerve cells of the body, waiting to become active again. Acyclovir is an antiviral medication that helps the body fight the infection. It does this by preventing the virus from multiplying.
 

Effects of Acyclovir

Several studies have examined how well acyclovir treats shingles, genital herpes, and chickenpox.
 
Shingles
In studies looking at acyclovir for shingles, the drug helped shingles lesions to heal faster and helped reduce pain. It also helped to prevent nerve pain associated with shingles. Studies suggested that acyclovir was more effective when started within the first 48 hours after symptoms appeared and worked better in people over 50 years old.
 
Genital Herpes
For people who took acyclovir to treat their first genital herpes infection, the lesions healed more quickly and were painful for a shorter period of time, compared to those who did not take acyclovir.
 
Studies also showed that acyclovir helps prevent outbreaks in people with frequent recurrences (six or more outbreaks per year). In these people, the drug reduced the frequency and severity of genital herpes outbreaks.
 
Chickenpox
In studies, acyclovir helped chickenpox lesions to heal 50 percent faster, reduced the number of lesions, and decreased the chance of fever or loss of appetite. In these studies, the drug was used within 24 hours after the appearance of chickenpox in children.
 

When and How to Take Acyclovir

General considerations for when and how to take acyclovir include the following:
 
  • The medication comes in the form of tablets, capsules, and a suspension (oral liquid). Acyclovir injection (used for more serious herpes infections), cream, and ointment are also available.
     
  • Acyclovir can be taken with or without food. If the medication bothers your stomach, try taking it with food.
     
  • Be sure to shake the liquid form of acyclovir thoroughly before each dose.
     
  • For the medication to work properly, it must be taken as prescribed. Make sure to take acyclovir as prescribed by your healthcare provider.
     

Dosing Information for Acyclovir

The dose of acyclovir that your healthcare provider recommends will vary, depending on a number of factors, including:
 
  • Your age and weight
  • The condition being treated
  • Other medications you may be taking
  • Other medical conditions you may have.
     
As is always the case, do not adjust your dose unless your healthcare provider specifically instructs you to do so.
 
(Click Acyclovir Dosing for more information.)
 

Side Effects of Acyclovir

As with any medicine, side effects are possible with acyclovir. However, not everyone who takes the drug will experience side effects. In fact, most people tolerate it quite well. If side effects do occur, in most cases, they are minor and either require no treatment or can easily be treated by you or your healthcare provider. Serious side effects are less common.
 
Common side effects of acyclovir include but are not limited to:
 
(Click Acyclovir Side Effects to learn more, including potentially serious side effects that you should report immediately to your healthcare provider. You can read about a specific acyclovir side effect by clicking Zovirax Hair Loss.)
 

Acyclovir Drug Interactions

Acyclovir can potentially interact with a few other medicines (see Drug Interactions With Acyclovir).
 

Acyclovir: What Should I Tell My Healthcare Provider?

You should talk with your healthcare provider prior to taking acyclovir if you have:
 
  • Kidney disease, including kidney failure (renal failure)
  • Any allergies, including allergies to food, dyes, or preservatives.
     
Also, let your healthcare provider know if you are:
 
Make sure to tell your healthcare provider about all medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements.
 
(Click Precautions and Warnings With Acyclovir to learn more, including information on who should not take the drug.)
 

What If I Take an Overdose of Acyclovir?

People who take too much acyclovir may have overdose symptoms that could include:
 
  • Agitation
  • Coma
  • Seizures
  • Lethargy
  • Kidney damage.
     
If you happen to overdose on acyclovir, seek immediate medical attention.
 
(Click Zovirax Overdose for more information.)
 

What Should I Do If I Miss a Dose of Acyclovir?

If you do not take your acyclovir as scheduled, take your missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule. Do not take a double dose.
 

Strengths of Acyclovir

Acyclovir tablets are available in the following strengths:
 
  • Acyclovir 400 mg
  • Acyclovir 800 mg.
     
Acyclovir capsules are available in one strength -- Acyclovir 200 mg.
 
Acyclovir suspension is available in one strength -- Acyclovir Suspension 200 mg per 5 mL (200 mg per teaspoonful).
 

Is There a Generic Version of Acyclovir?

Currently, both brand-name and generic acyclovir versions are licensed for sale (see Generic Zovirax).
 
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Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD;