Medicines & Supplements A to Z > Acyclovir


Last updated on June 26, 2019.

Overview   |   Dosage   |   Side Effects   |   Where To Buy  

GENERIC NAMES: Acyclovir, Aciclovir



What is Acyclovir for?

Acyclovir is an antiviral against herpes simplex virus types 1 and 2 as well as varicella-zoster virus (herpes zoster and chickenpox). It is indicated for the following conditions:

  • Treatment and prevention of herpes labialis (cold sores)
  • Genital herpes
  • Herpes zoster (shingles)
  • Prevention of herpes simplex in immunocompromised patients (eg elderly, patients suffering from infections, patients taking immunosuppressants)
  • Herpes simplex encephalitis (inflammation of the brain)
  • Herpes simplex keratitis (inflammation of the cornea)

How to use it?

Acyclovir is usually taken by mouth as a tablet. It is also available as a skin cream, which is applied to the skin, eye ointment, and an injectable formulation.

For herpes simplex keratitis

AdultTo the eye as 3% ointment

Apply inside the lower conjunctival sac 5 times daily every 4 hours. Continue treatment for at least 3 days upon the completion of healing.

For suppression of recurrent herpes simplex

Adult                        Oral – 800 mg daily in 2-4 divided doses and may reduce to 400-600 mg daily. Conditions should be reassessed every 6-12 months

For mild or infrequent recurrences: 200 mg 5 times daily for 5 days, preferably begin during the prodromal period

For primary herpes simplex infections

Adult / Child above 2 years Oral – 200 mg 5 times daily, usually every 4 hours while awake for 5-10 days. 

For severely immunocompromised patients: 400 mg 5 times daily for 5 days

For herpes zoster (shingles)

Adult            Oral – 800 mg 5 times daily for 7-10 days

For varicella-zoster virus infection

AdultOral – 800 mg 4 or 5 times daily for 5-7 days
Child above 2 years20 mg/kg (up to a maximum of 800 mg), 4 times daily for 5 days

For herpes simplex infections of skin

Adult                               Topical as 5% ointment / cream

Apply 5 or 6 times daily for 5-10 days, preferably begin in the prodromal period. 

What are the side effects of Acyclovir?

Common side effects of Acyclovir associated with use in the eye include eye inflammation and eye pain. Side effects of Acyclovir when taken by mouth include abdominal pain, diarrhoea, dizziness, fatigue, fever, headache, nausea, sensitive to sunlight (photosensitivity), skin reactions, and vomiting.

Where to buy Acyclovir in Hong Kong?

In Hong Kong, Acyclovir is a prescription only medicine, and requires a prescription from a doctor to be purchased in a pharmacy. It can also be obtained from doctors. To find a pharmacy near you, refer to the list of pharmacies (“Authorized Sellers of Poisons”) from the Hong Kong Department of Health.

For more information about drug names and ingredients, you can visit Hong Kong’s Drug Office at

For detailed information about the use of Acyclovir in children, pregnancy and breastfeeding, and for questions about drug interactions, please check with your pharmacist or doctor.

Disclaimer: our goal is to provide you with the most relevant drug information and common dosage for Hong Kong. This information does not constitute medical advice. For specific treatment recommendations and advice, always discuss with your doctor or pharmacist, and follow the instructions included with your specific medicine.