• Speeds healing and reduces outbreak duration
  • Relieves pain, tingling and cold sore discomfort
  • Reduces future outbreaks with daily suppressive therapy

How it works?

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Overview

Want to stop cold sores before they take over? Valtrex (Valaciclovir) Tablets are a powerful oral antiviral that helps shorten healing time, ease pain, and reduce the risk of recurrent outbreaks.

By tackling the herpes simplex virus (HSV-1) directly, Valtrex works fast — especially when taken at the very first signs of tingling or burning. For many, this means smaller, shorter, and less disruptive flare-ups, so you can get back to feeling confident and comfortable sooner.

This medicine requires a secure online consultation with a UK-registered prescriber, and will only be supplied if clinically appropriate.


What is Valtrex


Valtrex is a trusted antiviral treatment for cold sores and herpes outbreaks.
It contains valaciclovir, which converts in the body to aciclovir — a powerful agent that blocks the herpes virus from multiplying. Compared to standard aciclovir, Valtrex usually requires fewer daily doses, making it a convenient, high-strength option for effective symptom control.

Valtrex is used to:

  • Speed up healing when taken at the first sign of a cold sore or flare-up
  • Ease discomfort, including pain, burning, swelling, and redness
  • Reduce the severity of blisters and limit the spread of infection
  • Prevent recurrent outbreaks, especially in those with frequent symptoms

Directions

  • Take exactly as prescribed by your clinician.
  • The usual dose for cold sores is 2g twice in one day, taken 12 hours apart.
  • Swallow the tablets whole with water, with or without food.
  • For best results, start treatment as soon as the first symptoms appear.
  • Do not take more than the prescribed course.

Side Effects

Valtrex is generally well tolerated, but like all medicines, it can cause side effects in some people. Most are mild and temporary.

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

  •  Headache – the most commonly reported side effect, usually mild and short-lived.
  • Nausea or stomach upset – some people may feel sick or experience mild digestive discomfort.
  • Dizziness – if affected, avoid driving or operating machinery until it passes.
  • Tiredness – a general feeling of fatigue may occur, especially at the start of treatment.

Less common but serious (seek medical advice immediately if these occur):

  • Allergic reaction – including rash, swelling of the face or throat, or difficulty breathing.
  • Kidney issues – such as changes in urination, especially in dehydrated patients or those with pre-existing kidney conditions.
  • Confusion or hallucinations – rare, but more likely in older adults or people with kidney disease.

 

Disclaimer: This is not a complete list of side effects. Always read the patient information leaflet that comes with your medicine for full details. If you notice anything unusual or concerning, stop taking the medicine and seek medical advice promptly. In an emergency, call 999 or go to A&E.

Warnings

Do not take Valtrex if you:

  • Are allergic to valaciclovir, aciclovir, or any ingredients in the tablets
  • Have significant kidney or liver problems, unless your doctor has adjusted the dose


Other cautions:

  • Stay well hydrated during treatment
  • Tell your prescriber about any other medicines you take
  • Pregnant or breastfeeding women should only use under medical advice
Frequently asked questions

  • What is Valtrex 500mg and how does it work for cold sores?

    Valtrex 500mg contains valaciclovir, an antiviral medicine that stops the cold sore virus from multiplying. It helps reduce symptoms such as tingling, swelling and blistering, and can shorten recovery time when taken early.

  • How quickly does Valtrex 500mg treat cold sores?

    Valtrex starts working shortly after the first dose, with many people noticing improvement within one to two days. Taking it as soon as tingling begins gives the best chance of limiting how severe the outbreak becomes.

  • How should I take Valtrex 500mg for a cold sore outbreak?

    Valtrex is typically taken as four tablets twice daily for one day, or as advised by your clinician. Swallow tablets with water and begin treatment at the earliest sign of tingling or burning. Early use helps the medicine work more effectively.

  • Is Valtrex more effective than aciclovir for cold sores?

    Both medicines work well, but Valtrex may be more convenient as it is taken less often. Some people find it works faster or more reliably during severe outbreaks.Your clinician can advise which option suits your outbreak pattern.

  • Can Valtrex stop a cold sore if taken at the first sign?

    Yes. Starting Valtrex during the initial tingling or burning phase can sometimes prevent the cold sore from fully developing. Early treatment limits viral activity and can reduce swelling, discomfort and blister formation.

  • Who should avoid Valtrex 500mg tablets?

    People with kidney disease, weakened immunity or allergies to antiviral medicines may need different treatment. Always tell your clinician about all health conditions and medicines before starting Valtrex.

  • What side effects can occur with Valtrex?

    Side effects may include headache, nausea, stomach discomfort or dizziness. These usually settle quickly. Drink plenty of water during treatment, as dehydration can increase the risk of kidney-related side effects.

  • Can I use Valtrex 500mg for frequent or severe cold sores?

    Yes. Valtrex is often used by people who experience severe or repeated outbreaks.Your clinician may recommend short courses during each flare or daily suppressive treatment to reduce how often cold sores appear.

  • Does Valtrex help cold sores triggered by stress, sun or illness?

    Yes. Valtrex works regardless of the trigger by slowing viral replication. Many people find it useful during periods of stress, low immunity or sun exposure when outbreaks are more likely.

  • Can I take Valtrex 500mg with alcohol?

    Light alcohol consumption is generally safe, but drinking heavily may worsen dehydration, which increases the chance of kidney-related side effects. Drink water regularly while taking Valtrex.

  • Can Valtrex be combined with cold sore creams?

    Yes. Some people use antiviral creams alongside Valtrex to relieve local symptoms such as tingling or dryness. Apply creams separately and follow advice from your clinician on which combination is suitable.

  • Is Valtrex safe during pregnancy or breastfeeding?

    Valaciclovir may be used in pregnancy in certain situations, but you should always check with a clinician first. They will assess whether the benefits outweigh the risks for your specific symptoms.

  • What should I do if I miss a dose of Valtrex?

    Take the dose when you remember unless it is nearly time for your next one. Do not double the dose. Keeping doses spaced correctly helps maintain antiviral activity.

  • How fast does Valtrex work compared to Compeed patches?

    Valtrex works internally to limit virus multiplication, while Compeed patches protect the skin surface. Many people use both, as Valtrex tends to shorten the outbreak while patches reduce irritation and visibility.

  • Can I use Valtrex to prevent cold sores before holidays or big events?

    Yes. Some people take Valtrex preventatively if they know certain triggers, such as sun exposure or stress, often cause cold sores. Your clinician can advise whether this anticipatory approach is suitable.

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