Medicines & Supplements A to Z > Famciclovir


Last updated on 25/07/2021.

Overview   |   Dosage   |    Side Effects   |   Precautions  |   Tips  |   Where To Buy  

GENERIC NAME: Famciclovir



DRUG CLASS: Antivirals 

SUB CLASS: Guanine nucleoside analog

USED FOR: Herpes Simplex Virus Infection, Herpes zoster (Shingles)

AVAILABLE DOSAGE FORMS: 125mg, 250mg, 500mg (tablets)

What is Famciclovir for?

Shingles is caused by infection of varicella zoster virus (VZV). Patients will feel strong pain on the blisters formed as a group over their bodies. Shingles often takes place in older people who had chickenpox before. It can cause blindness if there are shingles near the eyes. Famciclovir inhibits DNA polymerase of VZV and other herpes viruses and stops virus proliferation to treat Herpes Simplex Virus infection and shingles.

How to use it?

Famciclovir is available as oral tablets.

Shingles infection
500mg 3 times a day for 7 days.
750mg 1-2 times a day for 7 days.
Immunocompromised Adult
500mg 3 times a day for 7 days, continue for 2 days after crusting of lesions.

Genital Herpes Suppression
250mg twice a day. Check every 6-12 months for recurrence frequency.
Immunocompromised Adult
500mg twice a day. Check every 6-12 months for recurrence frequency.

Genital Herpes Infection, first episode
250mg, 3 times a day for 5 days. Continue if a new lesion appears or incomplete healing.
Immunocompromised Adult
500mg twice daily for 10 days.

Genital Herpes Infection, recurrence
125mg, two times a day for 5 days.
1g twice a day for 1 day.
Immunocompromised Adult
500mg 2 times a day for 5-10 days.

Non-genital herpes simplex infection
Immunocompromised Adult
500mg 2 times a day for 7 days.

What are the side effects of Famciclovir?

Common side effects of Famciclovir include diarrhea, headache, nausea, vomiting and dizziness.

Who should not take Famciclovir?

Pregnant and breastfeeding women.
– Patients who are allergic to Famciclovir and any components in the formulation.

Pharmacist Tips:

– Patients with declined liver or kidney function need dose reduction.
– People who are concerned about shingles may seek vaccination or re-vaccination of varicella vaccine.
– People never infected with VZV are more likely to have chickenpox first.

Common dosing schedule:
Take Famciclovir 1-3 times daily for 5-10 days.

This schedule is for reference only, adjustments may be made according to individual needs.

Some common medications Famciclovir may interact with:
– Cladribine
– Talimogene laherparepvec (T-Vec)
Varicella vaccine
– Zoster vaccine

Please notify your doctor or pharmacist if you are taking the above medication, dosage adjustments might be needed.

Where to buy Famciclovir in Hong Kong?

In Hong Kong, Famciclovir 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

Need more information?

For detailed information about the use of Famciclovir 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.