Famciclovir is an antiviral medication used to treat infections caused by certain types of viruses, such as herpes simplex and varicella-zoster viruses [1]. However, the safety of using famciclovir during pregnancy has not been established, and it is generally not recommended for use in pregnant women [2].

According to the manufacturer's prescribing information, famciclovir should be used during pregnancy only if the potential benefit to the mother outweighs the potential risk to the fetus [3]. This is because animal studies have shown that famciclovir can cause fetal harm, including embryo-fetal toxicity and developmental abnormalities [3].

The U.S. Food and Drug Administration (FDA) classifies famciclovir as a pregnancy category B drug, which means that it is not expected to harm an unborn baby, but there is limited information available on its use during pregnancy [4]. However, the FDA notes that animal studies have shown that famciclovir can cause fetal harm, and that it should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus [4].

Therefore, if you are pregnant or planning to become pregnant, it is important to inform your healthcare provider before taking famciclovir. Your healthcare provider may recommend alternative treatments that are safer for use during pregnancy.

In summary, while famciclovir is an effective antiviral medication, its safety during pregnancy has not been established, and it is generally not recommended for use in pregnant women. Animal studies have shown that famciclovir can cause fetal harm, and it should be used during pregnancy only if the potential benefit outweighs the potential risk to the fetus.

Sources:

1. Famciclovir. Drugs.com. <https://www.drugs.com/famciclovir.html>.
2. Famciclovir. Mayo Clinic. <https://www.mayoclinic.org/drugs-supplements/famciclovir-oral-route/pregnancy/drg-20063061>.
3. Famvir (famciclovir) tablets, for oral use. Full Prescribing Information. Genentech, Inc. <https://www.gene.com/download/pdf/famvir_prescribing.pdf>.
4. Famciclovir. FDA. <https://www.fda.gov/drugs/postmarket-drug-safety-information-patients-and-providers/famciclovir>.
5. Famciclovir. DrugPatentWatch.com. <https://www.drugpatentwatch.com/drugs/famciclovir>.