Famciclovir helps treat and control viral infections like genital herpes. Famciclovir is a generic medicine but it is also available as the brand Famvir. Both medicines contain the same active ingredient famciclovir, and they both work in the same way to treat viral infections.
You can take famciclovir as a one day course, taking two 500mg famciclovir tablets in the morning and another two 500mg tablets in the evening. It works much in the same way as other antiviral medicines used to treat genital herpes, like aciclovir, famciclovir, and valaciclovir.
4 tablet(s) / 500 mg - £85.00
8 tablet(s) / 500 mg - £155.00
12 tablet(s) / 500 mg - £219.00
How does famciclovir work?
Famciclovir works by stopping the virus that causes genital herpes from multiplying. This allows your body’s immune system to fight off the virus, and allows the genital herpes outbreak to heal.
In the body, famciclovir first changes into a different form and becomes penciclovir. Penciclovir enters the body’s cells and becomes activated to block an important enzyme the virus needs to multiply. This reduces the amount of virus in the body, controlling the infection enough for the immune system to handle it.
Before taking famciclovir, tell your doctor if you have any problems with your kidneys or liver. You should also tell your doctor if you have any condition that may affect your immune system like pregnancy, cancer (and chemotherapy), or HIV.
Who cannot take famciclovir?
Famciclovir may not be suitable for everyone and is not recommended for:
- children or teenage age groups
- pregnant or breastfeeding women
- people who are allergic to famciclovir, penciclovir or any of its ingredients
Famciclovir side effects and drug interactions
As with other medicines, you may have some side effects when taking famciclovir.
Some common side effects of famciclovir may include:
- dizziness (avoid driving when taking famciclovir)
- feeling sick and vomiting
- stomach pain
Some uncommon or rare side effects of famciclovir include:
- heart palpitations
Before taking famciclovir, you should tell your doctor if you are taking any other medicines, including over the counter medications and herbal medicines.
Some medicines that may interact with famciclovir are:
- raloxifene (osteoporosis treatment)
- probenecid (gout treatment)
The full list of known side effects and cautions you should be aware of when taking famciclovir are in the patient information leaflet supplied with your medicine. Speak to your doctor for advice if you experience any of these side effects.
Famciclovir is a type of antiviral medicine used to treat viral infections like genital herpes. Genital herpes is caused by the herpes simplex virus types 1 and 2.
Some people who become infected with the virus may develop symptoms soon afterwards, while some may never develop symptoms. In others, it may take months or even years before they have a first episode of symptoms.
Some symptoms of genital herpes infection include:
- feeling unwell
- mild fever, with aches and pains
- swollen lymph nodes in the groin area
- itching and burning feeling around the genital areas
- burning pain when passing urine
- painful sores or blisters around your genitals, thighs and anus
- unusual vaginal discharge in women
If you think you have genital herpes, you can visit your GP or local sexual health clinic for testing. Genital herpes can be passed on as it is very contagious. You can pass it on even if you do not have symptoms.
You can get genital herpes:
- if you come into contact with cold sores
- through skin to skin contact with the affected area during vaginal, anal or oral sex
- by sharing sex toys with someone who has genital herpes
Apart from famciclovir, you can also treat genital herpes with:
- aciclovir 400mg 3 times a day
- valaciclovir 500mg 2 times a day
To get the most out of your treatment, it is better to take antiviral medicines as soon as you notice any symptoms of genital herpes, and ideally within 5 days.
Other ways you can manage the symptoms of genital herpes
- Bath the affected area in salt and water solution
- Apply vaseline or topical 5% lidocaine (painkiller) to manage pain when passing urine
- Apply an ice pack wrapped in a flannel to the affected area to help soothe the pain
- Take oral painkillers
- Avoid wearing tight or hugging clothes that may irritate the blisters or sores
- Avoid having vaginal, anal or oral sex until the sores have disappeared
- Drink more fluids so your urine may be more dilute and less painful when peeing
You should always take your medicines as advised by your doctor. You can take your famciclovir tablets with or without food.
To treat an outbreak of genital herpes, take 2 famciclovir 500mg tablets and then another 2 tablets 12 hours later. For example, 2 tablets are taken in the morning, and then another 2 tablets in the evening.
If you take more famciclovir tablets than you should, take your medicine pack and go to the nearest A&E department immediately. Taking an overdose of famciclovir may be harmful to your kidneys.
Dr Kathryn Basford
Dr Kathryn Basford is a qualified GP who works as a GP in London, as well as with ZAVA. She graduated from the University of Manchester and completed her GP training through Whipps Cross Hospital in London.Meet our doctors
Article created: 16 Sep 2021
Last reviewed: 16 Sep 2021
Famciclovir for viral infections (December 2019) Patient Info (Accessed 30 August 2021)
Famciclovir (September 2018) EMC (Accessed 30 August 2021)
FAMCICLOVIR NICE (Accessed 16 August 2021)
Genital herpes (September 2020) NHS (Accessed 30 August 2021)
Genital herpes (March 2018) Patient Info (Accessed 30 August 2021)