Famciclovir

Famciclovir is a generic medicine that is used to treat the herpes virus and 2 different types of viral infections:

• Genital herpes
• Shingles and chickenpox

You need a prescription from a doctor to get any famciclovir tablets. 

You can buy famciclovir tablets to treat genital herpes on Superdrug Online Doctor, but we do not offer famciclovir tablets to treat shingles and chickenpox. 

What’s the difference between famciclovir, aciclovir, and valaciclovir?

Aciclovir, famciclovir, and valaciclovir (also spelled Valacyclovir) are all antiviral drugs used to treat herpes. They are all generic medicines which means that they can be known by a different brand name (for example, Zovirax is the brand name for aciclovir).

Valaciclovir is a prodrug, which means it is not in its active form before you take it. Once you have taken it, it is converted inside your body into the active drug, aciclovir. A larger amount of valaciclovir enters the bloodstream this way, and has a better effect on the infection. 

Famciclovir is also a prodrug that changes into a different form once you take it, and becomes penciclovir. Penciclovir enters the body’s cells and then becomes active, blocking the enzymes the virus needs to multiply.

They are all equally effective in controlling outbreaks of herpes infections.

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Famciclovir works by stopping the infecting herpes virus from growing and spreading. This controls the infection and helps your body’s immune system fight it. Famciclovir is not a cure, as it does not remove the herpes virus from your body, but instead helps your body control it.

Since the virus reproduces very early in the infection, the sooner you start treatment the sooner famciclovir helps your body control the infection.

How long do famciclovir tablets take to work?

Famciclovir shortens the length of time an outbreak lasts. They are usually effective within a couple of days, but it can still take up to 10 days for the blisters or sores to heal. In this time you shouldn’t start to get any new sores. The sooner you take the tablet after symptoms appear the better they work.

How long does a herpes outbreak last while taking famciclovir?

The length of a herpes outbreak varies from person to person. An outbreak usually lasts around 7 to 10 days although the first time you get an infection it can last longer. Taking famciclovir can reduce the outbreak to 2 to 3 days, but there is no guarantee this will happen to you. 

How effective is famciclovir?

Famiciclovir can reduce how often recurrent genital herpes occurs by 70% to 80%.

Can I have sex while taking famciclovir?

If you are taking famciclovir, you should not have sex while you have symptoms of genital herpes, such as sores or blisters. Once they have healed you should still use a condom when you have sex to avoid passing the herpes virus onto your sexual partner.

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Famciclovir is taken orally and can be taken with or without food. You should follow your doctor’s instructions carefully when taking famciclovir as the dose varies depending on your specific circumstances. 

Your prescription will tell you how often to take your tablets and for how long. The dose, how often you have to take the tablets and for how long depends on whether you have a normal or reduced immune system and whether you are dealing with a first outbreak, a subsequent outbreak or want to prevent future outbreaks.

Famciclovir doses

For recurrent infections, you would normally be told to take 2 famciclovir 500mg tablets and then another 2 tablets 12 hours later. You could take 2 tablets in the morning, and then another 2 tablets in the evening, for example. Swallow them whole with water, and you can take them with or without food.

It is important that you continue your course of medication even if your symptoms have cleared up. 

What should I do if I take too many tablets?

If you take too many tablets or if someone else takes your tablets, you should seek medical advice from your doctor or the emergency department at a hospital immediately. This is because an overdose of famciclovir may affect the function of the kidneys. If someone already has kidney problems it can lead to kidney failure in very rare cases.

What should I do if I forget to take my tablet at the right time?

If you forget to take a dose of famciclovir and it is more than an hour until your next dose is due, take the tablet as soon as you remember. Then take your next dose as scheduled. 

If you forget to take a dose of famciclovir and it is less than an hour until your next dose is due, do not take the missed dose and take your next dose when scheduled to do so. Do not take a double dose to make up for a forgotten dose.

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You can buy famciclovir online from a registered and reputable online doctor, such as Superdrug Online Doctor, in a few simple steps:

• Fill in the brief questionnaire on our site. 
• Our doctors will then review your answers and make sure it is safe to prescribe you famciclovir. 
• You then decide how you would like to receive your prescription: either as a discreet package through the post or you can ‘Click and Collect’ it from your local Superdrug pharmacy.
• At any point, you can message our doctors for advice through your Patient Account.

If you are using a website to buy medication, the Government’s online checker can reassure you that the site you are using is operating legally and safely.

Can I get famciclovir tablets on the NHS?

Famciclovir is licensed for use in the UK, but it is not available on the NHS.

Can I buy famciclovir tablets over the counter?

No, you need a prescription to buy famciclovir tablets which means you cannot buy them over the counter.

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If it has been prescribed for you, famciclovir is safe to take. Like all medicines, it can cause side effects. These vary from person to person and in severity.

If you get any of the following serious side effects you should contact a doctor or go to the emergency department at a hospital immediately:

• severe blistering of the skin around lips, eyes, mouth, nose or genitals
• swelling below the surface of the skin
• unexplained bruising, purplish patches on the skin or nosebleeds
• yellowing of the skin (signs of jaundice)

If you get mild side effects they may go away within a few days. If they are more severe or don’t go away, talk to your doctor.

Common side effects (may affect up to 1 in 10 people):

• headache
• feeling or being sick
• stomach pain or diarrhoea
• dizziness 
• rash or itching
• liver function test giving abnormal results 

Uncommon side effect (may affect up to 1 to 100 people) include:

• confusion 
• drowsiness 
• hives 

Rare side effects (may affect up to 1 in 1,000 people) include:

• hallucinations 
• palpitations

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Do not take famciclovir if: 

• you are allergic to famciclovir or penciclovir, or any of the other ingredients (you can find a list in the Patient Information Leaflet)
• you have kidney problems now or in the past 
• you have problems with your body’s immune system
• you have liver problems
• you are a child or adolescent

If you are taking or have recently taken any other medication, tell your doctor so they can be sure famciclovir is safe for you to take. This is especially important if you are taking raloxifene, probenecid or any other medicine that can affect your kidneys.

Can I take famciclovir if I am pregnant, planning to get pregnant or breastfeeding?

If you are pregnant or breastfeeding, think you may be pregnant or are planning to have a baby, talk to your doctor before taking famciclovir.

If you are pregnant or breastfeeding, famciclovir is not to be used unless clearly necessary. 

If you are of child-bearing age and have genital herpes, do not have sex while you have symptoms even if you have started taking famciclovir to treat them.

Can I drink alcohol when taking famciclovir?

Famciclovir can cause dizziness, drowsiness and confusion. As alcohol can make these symptoms worse, it is recommended not to drink when taking famciclovir.

Can I drive or operate machinery when taking famciclovir?

If you experience side effects that make you drowsy, dizzy or confused, you should not drive or operate machinery while taking famciclovir.

Can I take paracetamol with famciclovir?

Paracetamol is not known to interact with famciclovir. Check with your doctor before taking other kinds of pain relief while taking famciclovir.

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Famciclovir 500 mg film-coated tablets EMC 2018 [accessed 6 July 2021]

Famciclovir NICE [accessed 6 July 2021]

Genital Herpes NHS 2020 [accessed 6 July 2021]

Aciclovir NHS 2019 [accessed 6 July 2021]

Famciclovir Side Effects, Dosage and more Healthline [accessed 6 July 2021]

Famciclovir Side Effects Drugs.com [accessed 6 July 2021]

Famciclovir for Viral Infections Patient Info 2019 [accessed 6 July 2021]

Genital HSV Infections Centers for Disease Control and Prevention [accessed 13 July 2021]

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