If you have searched for valaciclovir cream, valacyclovir ointment or topical Valtrex, there is an important point to clear up first: valaciclovir is not available as a licensed topical cold sore treatment in the UK. Valtrex is a brand of valaciclovir tablets, not a cream.
What is available is aciclovir 5% cream, which is applied to the affected area, and valaciclovir tablets, which are taken by mouth. They contain related medicines but deliver them in very different ways. This guide explains how each treatment works, what the evidence shows, the UK prescription rules, and how other cold sore products fit into the picture.
Why There Is No Valaciclovir Cream
Valaciclovir is a prodrug of aciclovir. This means the body converts valaciclovir into aciclovir after it is absorbed. The active antiviral effect comes from aciclovir, not from valaciclovir itself.
The Prodrug Problem
When you swallow a valaciclovir tablet, it is absorbed from the gut and rapidly converted into aciclovir and valine. This conversion is thought to be mainly carried out by an enzyme called valaciclovir hydrolase. The bioavailability of aciclovir from valaciclovir is around 54%, compared with much lower absorption from oral aciclovir. Food does not significantly reduce this bioavailability.
The point of making valaciclovir is to improve oral absorption. Once converted, it provides aciclovir in the bloodstream, where it can reach infected tissues throughout the body.
A topical valaciclovir product is not a standard licensed treatment for cold sores. The topical medicine used for cold sores is aciclovir, which is already the active antiviral drug.
Can You Crush a Valaciclovir Tablet and Put It on a Cold Sore?
No. Valaciclovir tablets are designed to be taken by mouth, not applied to broken or irritated skin. Crushing a tablet does not turn it into a suitable topical medicine, and the tablet also contains other ingredients that are not formulated for use on a cold sore.
If you have been prescribed valaciclovir, take it exactly as directed. If you want a topical treatment for a cold sore, ask a pharmacist about an appropriate aciclovir cream instead.
How Topical Aciclovir Cream Works
Aciclovir is an antiviral medicine that acts against herpes simplex virus. Inside infected cells, it is converted into its active form. The first step depends on a viral enzyme called thymidine kinase. The active drug then interferes with viral DNA production, which helps slow the virus from multiplying.
When aciclovir cream is applied to a cold sore, the medicine acts locally around the area where it is applied. Only a small amount is absorbed through the skin.
The timing matters. NHS guidance recommends starting aciclovir cream as soon as you notice the early itching or tingling associated with a cold sore. It may be less helpful once blisters have appeared.
Aciclovir does not remove herpes simplex virus from the body. The virus remains dormant in nerve cells between outbreaks, so treating one cold sore does not stop future outbreaks from happening.
How Valaciclovir Tablets Work
When you swallow valaciclovir, your body converts it into aciclovir. The active drug then works against herpes viruses in much the same way as aciclovir given by other routes. The main difference is how the medicine reaches the affected area. Oral treatment delivers aciclovir through the bloodstream rather than directly to one small area of skin.
For cold sores, a licensed valaciclovir regimen can be used in adults and adolescents when treatment is started at the earliest symptoms. One licensed regimen for herpes labialis is 2,000 mg twice in one day, with the second dose taken about 12 hours after the first. The exact dose may need to be changed in people with reduced kidney function.
Valaciclovir is also used for other herpes virus infections, including genital herpes and shingles, but the dose and length of treatment are different for each condition.
Taking an oral antiviral for one outbreak does not automatically prevent the next outbreak. Suppressive treatment is a separate, longer course that a prescriber may consider for people who have frequent or troublesome recurrences.
Cream or Tablets: What the Evidence Actually Supports
It is easy to make cold sore treatments sound more powerful than they are. Both topical and oral antivirals can help shorten a cold sore episode when they are used appropriately, but neither treatment removes herpes simplex virus from the body or guarantees that another outbreak will not happen.
Timing is one of the most useful things to understand. Antiviral treatment works against the virus while it is actively multiplying, so starting treatment during the early tingling or burning stage gives it the best opportunity to work. NHS guidance specifically recommends starting antiviral cream when early symptoms are recognised.
There is not a simple answer to which treatment is always better. The right option depends on the type of outbreak, how often you get cold sores, your medical history, and whether a prescriber thinks an oral antiviral is appropriate.
| Aciclovir 5% cream | Valaciclovir tablets | |
|---|---|---|
| Route | Applied to the affected area | Swallowed |
| Active drug | Aciclovir | Converted into aciclovir in the body |
| Where it acts | Mainly around the area where it is applied | Through the bloodstream |
| UK status | 2g packs are available without a prescription from pharmacies | Prescription only |
| Often used for | A localised cold sore, particularly when treatment is started early | Cold sores and other herpes infections where an oral antiviral is clinically appropriate |
| What it does not do | Does not remove the virus from the body or prevent future recurrences | Treating one episode does not automatically prevent future recurrences |
The legal status of aciclovir cream can depend on the specific product and pack size, so check the product information or ask a pharmacist if you are unsure. Small 2g packs are available for self care in the UK.
Aciclovir Tablets Compared With Valaciclovir
If both medicines ultimately provide aciclovir, why are there two different tablets?
The main difference is absorption and dosing. Oral aciclovir is only partly absorbed from the gut, with average bioavailability of around 10% to 20%. Valaciclovir was developed as a prodrug that is absorbed more efficiently and then converted into aciclovir. The bioavailability of aciclovir from valaciclovir is around 3.3 to 5.5 times higher than that historically seen with oral aciclovir.
This means valaciclovir can often be given less frequently than oral aciclovir for the same type of infection. The actual dose and schedule depend on the condition being treated and the person's kidney function.
Both oral medicines are cleared through the kidneys, so kidney problems are important to mention when you are being assessed. Your prescriber may need to adjust the dose. Drinking enough fluid is also important while taking oral aciclovir or valaciclovir, particularly if you have kidney problems.
Branded Versus Generic, and Why the Brand Can Cost More
Valtrex is a brand name for valaciclovir. Zovirax is a brand name for aciclovir.
A generic medicine contains the same active ingredient as the corresponding branded medicine and is designed to meet the same quality standards. A branded medicine is not automatically a stronger version simply because it has a brand name.
The price difference can reflect factors such as branding, packaging, marketing, supply and the pricing decisions of the manufacturer or pharmacy. It does not necessarily mean that the branded medicine contains a more powerful form of the active ingredient.
You may also see different brand names for valaciclovir in different countries. Check the active ingredient and the formulation carefully rather than assuming that a product with a similar sounding name is a cream.
What Else Is Sold for Cold Sores, and What It Actually Does
The cold sore section of a pharmacy can contain several different types of products. Some contain an antiviral medicine, while others mainly protect the skin or help with symptoms.
| Product type | Contains an antiviral | What it does |
|---|---|---|
| Aciclovir 5% cream | Yes | Helps slow herpes simplex virus replication in the area where it is applied |
| Aciclovir and hydrocortisone combination cream | Yes, plus a mild steroid | Used for early recurrent cold sores in some countries and may reduce progression to ulcerative lesions |
| Hydrocolloid cold sore patches | No | Cover and protect the sore and can absorb fluid |
| Lip balms and barrier products | No | Help moisturise and protect dry or cracked lips, but do not treat the virus |
| Propolis or herbal lip products | No | Marketed for cold sores, but they are not licensed antiviral treatments and evidence varies |
| Docosanol cream | Different antiviral treatment | Available for cold sores in some countries, including the United States, but not a standard UK option |
Aciclovir is available in topical, oral and injectable forms. For cold sores, the products people are most likely to encounter are topical aciclovir and, when clinically appropriate, oral antiviral treatment.
Combination creams containing aciclovir and hydrocortisone have also been studied. In a large randomised trial involving 1,443 people who developed a recurrent cold sore, the combination was more effective than aciclovir alone at reducing progression to an ulcerative lesion. This type of product is intended for early treatment and is not suitable for everyone. Availability also varies by country and product.
The UK Prescription Rules, in Plain Terms
This is one area where cold sore information can become confusing. Not every antiviral cold sore treatment requires a prescription.
- Aciclovir 5% cream in a small 2g pack. Available as a pharmacy or self care medicine in the UK, depending on the specific product. A pharmacist can advise whether it is suitable for you.
- Other aciclovir cream products and pack sizes. The legal status can vary by the specific licensed product, so check the packaging or product information.
- Aciclovir tablets. Prescription only.
- Valaciclovir tablets, branded or generic. Prescription only. UK licensed valaciclovir tablets are classified as prescription only medicines.
If you are buying a prescription medicine online, check that the pharmacy is registered with the General Pharmaceutical Council and that the required clinical assessment is carried out before a prescription only medicine is supplied.
Cold Sores After Lip Tattooing, Lip Blush or Filler
Procedures that involve the lips can sometimes trigger a cold sore recurrence in people who already carry herpes simplex virus. If you regularly get cold sores, it is worth mentioning this before having lip tattooing, lip blush, filler or another procedure involving the lips.
If you have a history of recurrent cold sores, ask a healthcare professional whether preventive antiviral treatment could be appropriate before the procedure. This is something to discuss in advance rather than waiting for a cold sore to appear.
If you already have an active cold sore, tell the practitioner before having the procedure. It may be appropriate to postpone treatment until the sore has healed.
If a cold sore appears after a procedure, follow the treatment advice given by your healthcare professional and the aftercare instructions from the practitioner who carried out the procedure. If the outbreak is severe, spreading or not improving as expected, seek medical advice.
Which Option Tends to Suit Which Situation
This is a guide to the conversation, not a personal treatment recommendation. Suitability depends on your symptoms, medical history and clinical assessment.
- A recognisable cold sore caught at the early tingling stage: topical aciclovir may be an option for some people and is available from pharmacies.
- Larger, more troublesome or recurrent outbreaks: a prescriber may consider an oral antiviral such as valaciclovir, depending on the circumstances.
- Frequent recurrences: it may be worth discussing whether suppressive antiviral treatment is appropriate rather than treating every outbreak separately.
- A weakened immune system, or a cold sore that is unusually severe or spreading: get medical advice rather than relying only on self care.
- Pregnancy or breastfeeding: speak to a pharmacist, doctor or prescriber before starting treatment so they can consider which option is appropriate for you. Aciclovir can often be used during pregnancy, but it is still sensible to check first.
- Existing kidney problems: tell your prescriber, particularly if an oral antiviral is being considered, because the dose may need to be adjusted.
- Children: treatment depends on age, the medicine and the condition being treated, so do not assume that an adult dose is suitable for a child.
Side Effects and Cautions
Aciclovir cream can cause mild burning or stinging at the application site. These effects are usually local rather than affecting the whole body. NHS guidance advises not to use cold sore cream inside the mouth or nose, in or near the eyes, or inside the vagina.
Oral antivirals can cause side effects such as headache, dizziness, nausea, vomiting, diarrhoea and rash. Most people do not experience serious problems, but your prescriber should know about your other medicines and any kidney problems.
Both aciclovir and valaciclovir can require dose adjustment when kidney function is reduced. Tell your prescriber if you have kidney disease or have previously been advised that your kidney function is reduced.
Do not use these medicines if you have previously had a serious allergic reaction to aciclovir, valaciclovir or an ingredient in the particular product unless a healthcare professional has advised you otherwise.
Get medical advice if your cold sore has not started to heal within 10 days, if it is very large or painful, or if your outbreaks are becoming more frequent or severe. If you develop eye pain, eye redness or changes in your vision, seek urgent medical advice because herpes simplex can affect the eye.
Treatment Options and Costs
| Treatment | Type | From |
|---|---|---|
| Aciclovir 5% Cream | Topical antiviral | £8.99 |
| Aciclovir Tablets | Oral antiviral | £12.99 |
| Valaciclovir | Oral antiviral | £18.99 |
| Valtrex | Branded valaciclovir | £34.99 |
Prices can change between pharmacies and over time, so use these figures as a guide rather than a guarantee of the price you will pay.
If you would like a prescriber to review which option may be suitable for your outbreak pattern, you can complete an online cold sore assessment. A prescriber will review your information and decide whether treatment is appropriate and, if so, which option may be suitable.
