In the body, famciclovir is converted to penciclovir, antiviral molecule with the action against the virus herpes simplex (HSV) type 1 and 2, the herpes varicella virus, the Epstein-Barr virus and cytomegalovirus.


In cells infected with the peniclovir it undergoes the modifications that allow it to remain inside them for more than 12 hours, during which it interferes with the synthesis of viral DNA, thus blocking its reproduction.


What is Famciclovir?


Famciclovir is used to treat chicken pox, herpes zoster (also used in immunocompromised individuals), the ophthalmic zoster and the genital herpes.


How should Famciclovir be taken?


The famciclovir is taken orally at doses of 500 mg. Typically, the dosage is 3 times a day for 7-10 days, to be taken either during or between meals.

In some cases, however, it may be recommended to undergo intravenous therapy. In particular, this type of administration can be recommended for some immunocompromised patients (especially in the case of ophthalmic zoster), complicated or disseminated herpes zoster, motor neuropathies, encephalitis and cerebrovascular complications.


Side effects associated with Famciclovir


The side effects most commonly associated with taking famciclovir include:


  • Headache
  • Dizziness
  • Drowsiness
  • Nausea
  • Vomiting
  • Abnormal liver function tests
  • Rash and itching


Less frequent side effects include confusion, rash and severe skin reactions, thrombocytopenia, hallucinations and cholestatic jaundice.


Contraindications and warnings associated with the use of Famciclovir


Famcilovir should not be taken in case of hypersensitivity to the active substance, to penciclovir or any of its excipients. In addition, the dosage should be modified in the event of impairment of the functioning of the kidneys, while the effectiveness of the treatment can be reduced in cases of hepatic impairment. Its use during pregnancy is recommended only if the benefits outweigh the potential risks; moreover, it is better to suspend or avoid breastfeeding in case it is necessary to take famciclovir.

No significant interactions were detected with other medicines, except for a possible increase in the concentration of penciclovir in the blood in those who take probenecid.