Famiciclovir side effects

What is Famciclovir?

Famciclovir (Famvir) is a prescription drug used to treat herpes infections caused by the herpes zoster virus (shingles) and herpes simplex virus (cold sores and genital herpes). It is prescribed both to treat outbreaks and for long-term suppressive therapy of herpes.

Famvir is the branded version of the drug produced by Novartis Pharmaceuticals. Generic versions are widely available.

The recommended dosage of famciclovir depends on the type and severity of the infection.

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For genital herpes, 250 mg 3 times a day for 5 days is the recommended course. It’s best to take Famvir as soon as you notice the first signs of an outbreak, such as mild pain or tingling in the affected area.

To suppress genital herpes, 250 mg of famciclovir can be taken 2 times a day for a maximum of 12 months.

If you have cold sores around your mouth, you should take a single dose of 1.5 g of Famvir.

For patients diagnosed with herpes zoster, a dose of 500 mg 3 times a day for 7 days is recommended.

It’s best to follow your doctor’s advice on how to take famciclovir.

Famciclovir side effects

Famvir is generally safe, but patients may experience some or all of the following mild side effects:

Headaches
Dizziness
Nausea and vomiting
Abdominal pain
Skin rash
Tingling sensation

If you experience any of the following side effects, consult a doctor as soon as possible:

Severe rash
Fatigue
Hallucinations
Muscle aches
Signs of jaundice such as skin yellowing
Abnormal heartbeat

Serious Side Effects of Famciclovir

Although more severe side effects are rare, call emergency medical help in case you experience any of the following symptoms, as they could be signs of a serious or severe allergic reaction:

Swollen face, throat, hands or feet
Difficulty breathing or swallowing
Itching or burning of the skin
Bruising across the body and/or abnormal bleeding
Blisters developing across the body
Seizures

A study of 455 patients with genital herpes found that suppressive therapy with famciclovir over 1 year was well-tolerated. Therefore, long-term therapy with famciclovir appears to be safe, but additional clinical trials are needed.

Famciclovir interactions

The following drugs are known to interact with Famvir (famciclovir):

Live zoster vaccine (Zovastax)
Varicella virus vaccine
Cladribine (Leustatin, Mavenclad)
Entecavir (Baraclude)
Pemetrexed
Talimogene laherparepvec
Digitoxin
Probenecid (Probalan)

It’s best to avoid drinking alcohol while taking famciclovir. Alcohol can worsen the side effects of famciclovir and make you feel dizzy and nauseous.

References

Faro S. (1998). A review of famciclovir in the management of genital herpes. Infectious diseases in obstetrics and gynecology, 6(1), 38–43. https://doi.org/10.1155/S1064744998000088
FAMVIR 250 mg Tablets - Summary of Product Characteristics (SmPC) - (emc). (2018). Retrieved November 1, 2019, from Medicines.org.uk website: https://www.medicines.org.uk/emc/product/1516/smpc
Saltzman, R., Jurewicz, R., & Boon, R. (1994). Safety of famciclovir in patients with herpes zoster and genital herpes. Antimicrobial agents and chemotherapy, 38(10), 2454–2457. https://doi.org/10.1128/aac.38.10.2454
Diaz-Mitoma, F. (1998). Oral Famciclovir for the Suppression of Recurrent Genital Herpes<SUBTITLE>A Randomized Controlled Trial</SUBTITLE>. JAMA, 280(10), 887. https://doi.org/10.1001/jama.280.10.887
Drugscom. (2019). Famciclovir Drug Interactions. Retrieved November 1, 2019, from Drugs.com website: https://www.drugs.com/drug-interactions/famciclovir.html