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How Effective Is Acyclovir for Chickenpox?

Acyclovir is a potent antiviral medication that can significantly reduce chickenpox symptoms and prevent complications, especially when taken within 24 hours of the rash appearing. It's particularly beneficial for high-risk individuals. Want to see how it could make a difference in recovery times and comfort levels? Visualize the impact with our accompanying photo journey. What could this mean for you or your loved ones?
Lee Johnson
Lee Johnson

Using acyclovir for chickenpox is an effective treatment in most patients, although in many cases the use of the drug isn’t necessary. Research on the effects of the treatment have shown that up to 95 percent of patients who received treatment with acyclovir stopped developing the characteristic lesions associated with chickenpox about four days after the treatment was started. In contrast, out of subjects receiving the placebo treatment, only about 20 percent were still developing the lesions after six days.

Chickenpox is a type of herpes virus, caused by the varicella-zoster virus. Around 90 percent of people who contract the virus are younger than ten years of age. Most of the time, using acyclovir for chickenpox is unnecessary, because most healthy children can fight off the virus without help from external medications. The condition is characterized by a fever presenting with fluid-filled lesions on the face, body, and scalp. These lesions are notoriously itchy, but usually dry up around five days after the onset of the condition.

A boy with chickenpox.
A boy with chickenpox.

Generally, the effects of the condition are mild, but serious complications do occur in rare cases. This is usually only the case in patients with an already weakened immune system. As a result, patients who have a history of immunity issues will generally be recommended a treatment such as acyclovir for chickenpox. Otherwise healthy patients are unlikely to be advised to take the treatment, because most will be starting to recover within six days of the onset of the condition.

A girl with chickenpox.
A girl with chickenpox.

Acyclovir is classed as an antiviral drug, and can also be used for treatment of herpes, shingles, and Epstein-Barr virus. The drug is actually activated by the cells of the virus, which ordinary replicate themselves and destroy ordinary, healthy cells in the process. When acyclovir for chickenpox is used, the drug merges with the virus, which attempts to use it instead of the nucleoside it usually requires to spread. The result of this is a reduction in the spread of the condition.


Studies into acyclovir for chickenpox have had generally positive results. One large study took 815 patients who had developed chickenpox 24 hours before the trial began. These subjects were randomly split into two groups, one of which received acyclovir and the other group was given a placebo. After the initial four day observation period, 95 percent of the patients receiving acyclovir for chickenpox had stopped developing the rash. At the six day mark, 20 percent of the placebo group were still developing the rash associated with the condition.

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Discussion Comments


I was treated with acyclovir when I had chickenpox. I'm one of the few people who have had chickenpox as an adult.

I actually asked my doctor why I needed medication since kids usually get through chickenpox without anything and he told me that adults with chickenpox are more likely to have complications. Apparently, chickenpox is more dangerous for adults than it is for children. That's why he insisted that I take acyclovir and I think it really helped shorten the length of the breakout.


@fBoyle-- Does your son have a weak immune system or skin problems like eczema? I'm wondering why the doctor gave him acyclovir in the first place.

Acyclovir is effective for chickenpox, but only when it's started soon after chickenpox develops. It's also most effective in children who have a weak immune system and who are prone to immunity related skin conditions like eczema.

If acyclovir did not work for your son, either he started taking it too late or he is a healthy child and did not need it.


My son was given acyclovir for chickenpox but the medication did not make a difference. He continued to get new spots and the spots healed only after ten days. I'm sure that's how long the chickenpox would have lasted without the medication.

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