Prescription:

Zovirax (Acyclovir) is used to treat the symptoms of infections caused by the herpes virus, such as genital herpes. As well, it is used to prevent infections from coming back. It is also used to treat varicella-zoster virus (chickenpox) and herpes zoster (shingles).

Zovirax (Acyclovir) does not cure genital herpes infections. Zovirax (Acyclovir) helps relieve symptoms of genital herpes, such as pain and itching, helps sores to heal more quickly and prevents new ones from forming. For shingles, Zovirax (Acyclovir) should be started within 72 hours of the appearance of the rash in order for it to work. Zovirax (Acyclovir) will not prevent postherpetic neuralgias.

Why is this drug prescribed?

Zovirax tablets and suspension contain the active ingredient aciclovir, which is an antiviral drug used to treat infections with herpes viruses. Aciclovir tablets and dispersible tablets are also available without a brand name, ie as the generic drug. The herpes viruses include the viruses that cause cold sores and genital herpes and the virus that causes chickenpox and shingles. Aciclovir works by stopping these herpes viruses from reproducing and infecting more cells in the body. Aciclovir is converted to a more active form inside cells of the body that are infected with herpes viruses. The activated aciclovir then works by blocking the action of a viral enzyme called DNA polymerase. The herpes viruses need the DNA polymerase enzyme to copy their genetic material from RNA to DNA. This process is necessary for the viruses to multiply and continue to survive. By blocking the action of DNA polymerase, aciclovir prevents the herpes viruses from multiplying. This controls the infection and helps the immune system to deal with it. Aciclovir is taken by mouth to treat herpes infections that cause chickenpox and shingles. It is also taken by mouth to treat genital herpes and other herpes simplex infections of the skin and mucous membranes, and to prevent these infections coming back in people who suffer recurrent infections. Oral aciclovir is also valuable for preventing herpes simplex infections in people whose immune systems are supressed and cannot fight off infection, either due to disease, eg HIV and AIDS, or medical treatment, eg chemotherapy, steroids, bone marrow transplant. Aciclovir is also available as creams specifically for treating genital herpes and cold sores, and as an eye ointment for treating herpes simplex infections of the eye. See the factsheets linked at the end of this page for further information about these drugs.

Treatments

* Chickenpox. * Genital herpes. * Herpes simplex infections of the skin, eg cold sores. * Preventing herpes simplex infections in people whose immune systems are impaired, eg due to disease or treatment. * Preventing recurrence of herpes simplex infections, eg recurrent cold sores or genital herpes. * Shingles.

What side effects can this drug cause?

* Headache. * Dizziness. * Nausea and vomiting. * Abdominal pain. * Diarrhoea. * Skin reactions such as rash and itch. * Abnormal reaction of the skin to light, usually a rash. * Fatigue. * Fever. * Shortness of breath. * Alteration in results of liver function tests. * Confusion. * Agitation. * Shaky movements and unsteady walk. * Convulsions. * Sleepiness. * False perceptions of things that are not really there. * Disturbance in the components of the blood. * Inflammation of the liver. * Decreased kidney function.