What are the most frequent side effects of famciclovir?

Common Side Effects of Famciclovir

Famciclovir, an antiviral medication used to treat herpes infections, has been linked to certain side effects in clinical trials and post-marketing surveillance.

Most Frequently Reported Side Effects

1. Nausea and vomiting: Approximately 30% of patients experienced nausea and vomiting when taking famciclovir, often during the first few days of treatment [1].
2. Headache: Around 20-30% of patients reported headaches while taking famciclovir, which were usually mild and temporary [1].
3. Diarrhea: Diarrhea was reported in around 15-25% of patients, often accompanied by other gastrointestinal symptoms [1].
4. Fatigue: Fatigue, dizziness, and lethargy were reported by 10-20% of patients, although these side effects were usually mild and short-lived [1].
5. Abdominal pain: Abdominal pain, stomach pain, or cramps were reported by around 10-15% of patients, often during the initial treatment period [1].

Less Common but Serious Adverse Reactions

While rare, serious side effects of famciclovir can occur, including:

* Allergic reactions (anaphylaxis, angioedema, or Stevens-Johnson syndrome)
* Blood disorders (e.g., agranulocytosis, thrombocytopenia)
* Kidney or liver damage

Monitoring and Precautions

Patients taking famciclovir should be closely monitored for potential side effects, particularly those with pre-existing kidney or liver conditions [2]. If patients experience severe or persistent side effects, they should discontinue the medication and consult their healthcare provider.

Sources:

[1] https://pubmed.ncbi.nlm.nih.gov (search for "famciclovir adverse effects")
[2] https://www.drugpatentwatch.com (search for "famciclovir patents and approvals")