Acyclovir is an antiviral drug that slows down the growth and spread of the herpes virus in the body. Acyclovir is not a cure for herpes, it can only reduce the symptoms of the infection. Acyclovir is used to treat infections caused by herpes viruses such as herpes simplex, shingles, herpes meningitis and chicken pox.

Mechanism of action

Acyclovir after converting to acyclovir triphosphate competitively inhibits DNA polymerase enzyme. And it competes with natural deoxyguanosine triphosphate to join viral DNA. As a result, it prevents the creation of viral DNA.


Acyclovir is a synthetic purine nucleoside analog that has an inhibitory effect on herpes simplex viruses type 1 (HSV-1 (HSV-2), 2) and varicella zoster virus (VZV).


The oral bioavailability of acyclovir is 10 to 20%. Food does not affect the absorption of acyclovir.
Acyclovir is widely distributed in body fluids and tissues.
The highest concentration of acyclovir is in the central nervous system and about 50% of its plasma concentration.
Acyclovir is metabolized by the liver and is mainly excreted unchanged by active tubular secretion through the kidneys.
Skin absorption of acyclovir is negligible. The half-life of acyclovir is 2.5 to 3 hours.

Acyclovir uses

Herpes zoster, chicken pox, genital herpes

Dosage of acyclovir

Usual Dosage for Herpes Zoster: Adults:

Acute herpes zoster:

800 mg orally every 4 hours (5 times a day) for 7 to 10 days
Severe cases, immunocompromised patients: 10 mg/kg as a diluted solution is intravenously infused every 8 hours for 7 to 14 days.
The treatment may be started within 72 hours after the appearance of skin lesions, so clinical research has shown that if the treatment is started within the first 48 hours, acyclovir has the greatest effect.

Usual Dosage for Varicella Zoster: Adults:

Chicken pox:
Patients with a healthy immune system 800 mg orally, 4 times a day, for 5 days.

Immunocompromised patients:
10 mg/kg as a diluted solution is intravenously infused every 8 hours for 7 to 10 days.

Usual dosage for herpes simplex: Children:

HSV infection of infants: less than three months of age:
10 to 20 mg/kg or 500 mg/m2 intravenously every 8 hours for 10 to 21 days
According to some clinical studies, the recommended amount for premature babies is 10 mg/kg every 12 hours.

prohibited usage

Hypersensitivity to this drug and its ingredients
Acyclovir side effects
Nausea, headache, vomiting, angioedema, diarrhea, peripheral edema, fever, malaise, pain, anaphylactic reactions.

Drug interactions

Tenofovir, adefovir, mycophenolate mofetil, meglumine compound, tropistrone, foscarnet, diatrizoate (amidoterizoic acid), meglumine utalamate, zoster vaccine, ioxaglate, metaxalone, blonanserin, pholcodine, florbetapir F18, sodium aminohipporate.


1- Acyclovir capsules are for oral use only.
2- Acyclovir should be used with great caution in case of dehydration, kidney failure or neurological disorders.


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