Acyclovir Zovirax medication use, herpes dosage, benefits and side effects
September 14 2017 by
Ray Sahelian, M.D.


Acyclovir is used to treat herpes virus infections such as oral herpes, shingles, herpes simplex, genital herpes, and chicken pox. Acyclovir interferes with the activity of enzymes needed for the replication of viral DNA in cells. By preventing the multiplication, the herpes virus cannot multiply as easily. The FDA approved the use of acyclovir in 1984. Another option is valacyclovir.


Does acyclovir cure herpes?
Unfortunately, acyclovir does not cure the disease and infections can return at a later time. Acyclovir is prescribed as a cream or ointment (topical use), oral tablets, or intravenous liquid to relieve pain, speed recovery, and prevent viral shedding. More recently, acyclovir has been used in combination with AZT, to treat AIDS patients.

Availability by prescription
Acyclovir is found at a pharmacy in capsules, tablets, liquid, ointment, and doctor or hospitals have acyclovir in injection form.


Effectiveness of Acyclovir for herpes

Multiple studies of its use for the treatment of herpes labialis have suggested that the nominal efficacy of the topical formulation is the result of inadequate penetration of the drug into the target site of infection, the basal epidermis.
     Postherpetic neuralgia (PHN) is a complication of shingles (herpes zoster), a painful rash due to varicella-zoster virus reactivation. Studies of patients with PHN and zoster sine herpete (radicular pain without rash) support the notion that low-grade viral ganglionitis contributes to pain. If chronic pain reflects active infection, then antiviral therapy may help patients with PHN. Intravenous acyclovir at a dosage of 10 mg/kg every 8 hours for 14 days followed by oral valacyclovir at a dosage of 1000 mg 3 times per day for 1 month may provide some clinical improvement.


Acyclovir for Pityriasis Rosea condition

Acyclovir may be effective in the treatment of pityriasis rosea, especially in patients treated in the first week from onset, when replicative viral activity of HHV is probably very high.


Chickenpox infection

Acyclovir appears to be effective in reducing the number of days with fever and the maximum number of lesions among otherwise healthy children with chickenpox. However, the results of studies have not been overly convincing with respect to the number of days to no new lesions and relief of itchiness. The clinical importance of acyclovir treatment in otherwise healthy children remains uncertain.

Dosage and dose
Oral Acyclovir dosage --  For genital herpes acyclovir dosage : Up to 1,200 mg a day in evenly distributed doses, every four or eight hours taken with food. For shingles acyclovir dosage : Up to 4,000 mg a day in evenly distributed doses every four hours. For chicken pox acyclovir dosage : Up to 800 mg, four times a day, not to exceed 3,200 mg a day. Topical form-- To relieve herpes symptoms acyclovir dosage : Apply a small amount to lesions every three hours (six times a day) for seven days. Use a glove when applying acyclovir ointment.


Journal of Clinical and Diagnostic Research 2013. A comparative study to evaluate the efficacy and safety of acyclovir and famciclovir in the management of herpes zoster. In conclusion, oral famciclovir administered three times daily for 7 days during acute zoster infection is as effective as acyclovir, administered 800mg five times daily.In addition it offers significant benefit by providing a well tolerated, cost effective, convenient dosage regime and accelerated rate of lesion resolution and a reduced duration of PHN.

Acyclovir side effects, safety, influence on disease, interactions
Acyclovir side effects may be more common in older persons. Common adverse reactions include upset stomach,  vomiting, diarrhea, dizziness, tiredness, pain, especially in the joints, and changes in vision.


Use of acyclovir may cause complications in patients with liver or kidney disease, since these organs work together to remove the medication from the body.


BMJ Case Rep. 2014. Herpes zoster encephalopathy or acyclovir neurotoxicity: a management dilemma. This is a case report of a 69-year-old morbidly obese woman who presented with mental status changes after she was treated with acyclovir for shingles. The predominant symptoms were word-finding difficulties and visual hallucinations. Complicating her presentation was acyclovir-induced acute renal injury causing her creatinine level to rise up to 7.4 mg/dL. Acyclovir was discontinued on the suspicion of acyclovir neurotoxicity. Even though PCR for varicella zoster virus in the cerebrospinal fluid was positive, acyclovir was not restarted and the patient continued to improve and returned to her baseline.


Acyclovir and HIV rate
Long-term treatment of genital herpes with the drug acyclovir does not reduce the rate of new HIV infections

Acyclovir has been used by pregnant women and no birth defects or other related problems have been reported; however, studies of acyclovir in pregnancy in humans have been limited and inconclusive.

Breast Feeding
Acyclovir may pass into breast milk. Breast feeding should be avoided while taking any oral form of the drug. No problems are expected with the topical form.

Infants and Children
Acyclovir should not be used for children under two years of age. Its use for children under 12 should be carefully supervised by a physician.

Food Interactions with acyclovir
No significant food interactions have been reported.

Dietary supplement interactions
Does the herb hoodia have an influence on or interact with acyclovir treatment?
   We have not seen any such studies so it is difficult to say. Probably not.