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Valaciclovir is an antiviral medicine used to treat genital herpes. You can use valaciclovir the first time you get an outbreak. It’s also used to treat repeat outbreaks or to prevent outbreaks from happening.
Valaciclovir is a more affordable, generic alternative to Valtrex. It’s prescription-only, so a doctor needs to approve treatment for you. You should see results in 48 hours and it reduces overall recovery time by around 20%.
20 tablet(s) / 500 mg - £69.95
6 tablet(s) / 500 mg - £29.95
12 tablet(s) / 500 mg - £44.95
18 tablet(s) / 500 mg - £79.95
10 tablet(s) / 500 mg - £39.95
20 tablet(s) / 500 mg - £69.95
30 tablet(s) / 500 mg - £89.95
84 tablet(s) / 500 mg - £219.00
- a prescription-only medication
- antiviral (works on infections caused by viruses)
- the generic (cheaper) version of Valtrex
- useful for genital herpes, cold sores, and shingles
Valaciclovir is an antiviral medication (meaning it works against viruses) and is used to manage HSV (herpes simplex virus) and VZV (varicella-zoster) infections.
Valaciclovir for herpes
Valaciclovir is used to treat outbreaks of symptoms (flare-ups) or taken every day over 6 to 12 months to prevent herpes outbreaks if you get them often. It can help you by reducing the time to heal from an outbreak and lowers the chances of you passing the virus on to someone else.
While valaciclovir eases the symptoms, it does not cure herpes. There’s no current cure for genital herpes or cold sores. But it can help you by treating outbreaks or suppressing the virus to keep it in a dormant (inactive) state to prevent outbreaks and stop you from getting symptoms.
Valaciclovir for cold sores
Like with genital herpes, valaciclovir can also treat and prevent cold sore outbreaks. It’s used as a cream on cold sores directly or as a tablet to treat and prevent outbreaks.
Valaciclovir for shingles
Additionally, valaciclovir can be effective against shingles outbreaks. If used at the start of the infection, valaciclovir can help make the symptoms less severe and stop them lasting as long.
Valaciclovir is known as a prodrug, which means your body changes it into another substance after you take it. Valaciclovir turns into aciclovir, which works by blocking the virus from reproducing and slowing down how fast it spreads. This helps to control your symptoms and prevent outbreaks.
How long does it take for valaciclovir to work?
You should see the first results around 48 hours after you start taking valaciclovir.
For genital herpes, it can take up to 10 days for sores to fully heal, even with valaciclovir.
For cold sores, valaciclovir does speed up recovery but it can still take 7 to 10 days before the sores go away completely.
Valaciclovir is an effective herpes treatment. It reduces the time for sores to clear up by about 20%. Of the people who use it, 59% have no visible herpes symptoms after five days.
You may get fewer or less serious side effects with valaciclovir compared to the other genital herpes medications.
It’s important to remember that valaciclovir cannot cure herpes. No treatment can. But, if you take valaciclovir, it can help you control the virus and reduce your symptoms.
Valaciclovir is prescription-only, which means you need to go to your doctor or use an online service like ZAVA to get valaciclovir prescribed to you. If your regular GP gives you a physical prescription, you can get it filled at most pharmacies in the UK.
You should swallow the valaciclovir tablet whole with a glass of water at the same time each day. Follow the instructions given to you by your doctor or pharmacist. Check the patient information leaflet that comes with your medication if you’re not sure.
The sooner you start treatment, the better the effect will be. Try to take the first tablet as soon as you notice your symptoms. Starting it 2 hours after the infection begins can reduce how long you have symptoms by a whole day.
Make sure you complete your full course of treatment, even if your symptoms go away. This will reduce the risk of the infection coming back.
How do I know if my treatment is working?
You should notice your symptoms improve and the blistering dies down while you’re taking the treatment. If you’re still getting new blisters after finishing treatment, you should speak to a doctor.
Can I still have sex during herpes treatment?
You should avoid having sex while taking herpes treatment because you may spread it to your partner. This includes oral and anal sex. If you do have sex, you must use protection.
Can I drink alcohol on valaciclovir?
You can drink alcohol while taking valaciclovir. Alcohol does not interact with valaciclovir in the body. But, it does make your immune system weaker making it harder for you to recover.
Valaciclovir and pain medication
Valaciclovir can be taken with pain medication but some will interact with valaciclovir and increase the risk of kidney problems. Don’t take medications containing ibuprofen or naproxen. There’s no evidence that valaciclovir reacts with paracetamol or aspirin, so they should be safe to take.
Taking valaciclovir when pregnant
There’s no evidence that valaciclovir causes birth defects, so it should be safe to take when pregnant. Always tell your doctor you’re pregnant when getting herpes treatment so they recommend the right treatment course for you.
How much valaciclovir you need will depend on:
- if you’re using it to treat cold sores, genital herpes, or shingles
- if this is your first outbreak (flare-up)
- if you get recurring outbreaks
- if you’re taking it to prevent outbreaks
A doctor will tell you how much you should take, so it’s important to follow their instructions.
This dose twice a day is best for people who have already had their first genital herpes outbreak and are having repeat outbreaks. It can also be used once a day to prevent genital herpes outbreaks.
This dose can be used to prevent genital herpes outbreaks when taken twice a day. It is also used twice a day when you’re having your first outbreak. For shingles treatment patients usually take this dose three times a day for seven days.
Dosage for cold sores
When used to treat cold sores, valaciclovir is taken every twelve hours for one day at a strength of 2000mg.
Nearly all medications can cause side effects, but not everyone will get them.
Common side effects include:
- headache (1 in 10 may experience headaches)
- feeling sick (nausea) and being sick (vomiting)
- sensitivity to light (photosensitivity)
- skin reactions (rashes and itching)
Make sure you drink plenty of fluids during the treatment. You should not drive or use heavy machinery if you feel dizzy or sleepy while taking valaciclovir.
A full list of more, less common side effects is below. If you get a serious allergic reaction (symptoms are facial swelling, itchy skin and difficulty breathing), stop taking valaciclovir immediately and call 999 straight away.
Uncommon side effects:
- Abdominal (tummy) discomfort
- Agitation or confusion
- Shortness of breath
- Blood in your pee
- Changes in your blood like a lower number of white blood cells (mainly seen in people with a weakened immune system) or reduced platelet count
- Feeling drowsy
- Kidney pain
- Hive-like rash
Rare or very rare side effects:
- Swelling under the skin
- Unsteadiness while walking or a lack of coordination
- Delirium (disturbed thoughts) and psychosis
- Slow or slurred speech
- Altered brain function
- Kidney problems or kidney stones
- Fits or seizures
Side effects affecting your brain or nervous system are generally seen in people taking high doses (8000mg daily) and are usually reversible.
Always read the patient information leaflet that comes with your medicine for more information about side effects.
You should always speak to a doctor if you get any of these side effects or any other changes.
Long-term side effects
Generally, valaciclovir is safe for long-term use and well-tolerated by people using it over a longer period of time.
Problems mainly show up in people who have pre-existing health issues: If taken long-term by people who are often dehydrated or already have kidney problems, valaciclovir can cause renal toxicity. It can also cause liver inflammation in people who have liver problems.
Other medications can affect the way valaciclovir works in your body. You must tell a doctor if you’re on any of the following medications before taking valaciclovir:
- anything you’re taking without a prescription, including herbal medicines
- medications that affect the kidneys, including aminoglycosides, organoplatinum compounds, iodinated contrast media, methotrexate, pentamidine, foscarnet, ciclosporin, tacrolimus, cimetidine and probenecid
Tell a doctor about other medicines you’re using if you’re taking valaciclovir for shingles or after having an organ transplant.
You must not take valaciclovir if you’re allergic to any of its ingredients which can be found in the patient information leaflet that comes with your medicine. Speak to a doctor, pharmacist or nurse before taking valaciclovir if you:
- are over 65
- have kidney problems
- have liver problems
- have a weak immune system
Try and avoid becoming dehydrated while taking valaciclovir since this makes kidney problems more likely.
Speak to a doctor if you’re pregnant, trying to get pregnant or breastfeeding and wish to take valaciclovir.
- From £29.95 at ZAVA
- 59% effective*
- The dosage for regular herpes outbreak is 500mg twice a day for three days
- From £19.95 at ZAVA
- 54% effective*
- The dosage for regular herpes outbreak is 400mg twice a day for five days
*from research comparing aciclovir and valaciclovir, which shows the amount of patients who didn’t have any of the herpes virus visible in their body after five days of treatment.
Valaciclovir works in a similar way to other genital herpes treatments, including aciclovir. Some reports show that people get fewer or less serious side effects with valaciclovir compared to the other genital herpes medications.
Aciclovir and famciclovir (also known by the brand names Zovirax and Famvir, respectively) are the other approved treatments for genital herpes in the UK. Famciclovir is more commonly used to treat shingles or herpes and cold sores in people who have weakened immune systems.
Valaciclovir can also be more convenient than other medications, like aciclovir, because you don’t need as many tablets a day for herpes. Many doctors prefer prescribing valaciclovir over aciclovir, because of the simplified dosing schedule.
Frequently asked questions
Is valaciclovir an antibiotic?
No, it’s an antiviral. Antibiotics only work on infections caused by bacteria. Herpes, cold sores, and shingles are all caused by viruses. Antibiotics won’t work on these infections but antivirals like valaciclovir can.
How long does valaciclovir stay in your system?
Valaciclovir takes about 24 hours to leave your system completely. It is converted into aciclovir in the body and afterwards it has a half life of around 3 hours. This means that after three hours, only half of the medication is still in the body. It takes a lot longer for the second half to leave the body.
What’s the difference between the white and blue pills?
Valaciclovir, like any medication, can be coloured. Whether the pill is white or blue doesn’t make a difference to the way the medication works. It also isn’t related to which doses they contain either since the same dose pill can be different colours. See these valaciclovir images on drugs.com for more information.
Which dose is better, 500mg or 1000mg (1g)?
The best dose is the one prescribed to you by your doctor. 500mg and 1000mg are used by different people for different conditions. It also depends on whether it’s their first outbreak of herpes. 1000mg may be more effective but comes with a higher risk of side effects which is why it’s up to a doctor to pick the right dose for you.
Why is valaciclovir called generic Valtrex?
Valtrex is the branded version of valaciclovir. This means that GlaxoSmithKline, who originally held the patent for valaciclovir, chose Valtrex as its brand name. Until the patent ran out in 2009, only GlaxoSmithKline could sell valaciclovir. Now it can be manufactured by other companies as a generic drug, meaning it can be priced more competitively.
Can valaciclovir treat Covid-19?
No. Valaciclovir is not a good treatment for Covid-19. While it can effectively treat outbreaks of the viruses HSV and VZV, it doesn’t work with all viruses. It should never be sold as a Covid-19 treatment and anyone doing so is doing it illegally.
Does valaciclovir expire?
Yes, like all medications, valaciclovir has an expiration date. It is advised that you keep it refrigerated and use it within 28 days. Your valaciclovir packet should come with an expiration date printed on it.
What if valaciclovir isn’t working?
If your herpes symptoms do not go away after you’ve finished your full course of treatment, go back to your doctor. It might be that you need to try a course of a different medication.
Dr Babak Ashrafi Clinical Lead for Service Expansion
Accreditations: BSc, MBBS, MRCGP (2008)
Babak studied medicine at King’s College London and graduated in 2003, having also gained a bachelor’s degree in Physiology during his time there. He completed his general practice (GP) training in East London, where he worked for a number of years as a partner at a large inner-city GP practice. He completed the Royal College of GPs membership exam in 2007.Meet our doctors
Last reviewed: 23 Aug 2023
Genital herpes (2020) NHS [accessed April 2023]
Herpes simplex - genital: Management (2017) NICE [accessed April 2023]
Valaciclovir (2021) BNF [accessed April 2023]
Valaciclovir 500mg film coated tablets (2019) EMC [accessed April 2023]
Valaciclovir for viral infections (2019) Patient.info [accessed April 2023]
You can treat genital herpes two ways. One treatment option is for when you experience an individual outbreak (acute therapy) and the other is treatment for when you need to avoid regular outbreaks (suppressive). ZAVA offers both types of treatment through a discreet, convenient service.