Aciclovir cream is an established treatment for cold sores, but it is worth having realistic expectations about how much it can help and how quickly. Some people may notice their symptoms starting to improve during the first few days of treatment. However, the overall benefit is usually modest. When used correctly five times a day for five days, clinical studies suggest that aciclovir cream may shorten healing time by around half a day to one day on average, rather than making a cold sore disappear quickly.
For adults in the UK looking for clear, evidence based advice on cold sore treatment, this guide explains what topical aciclovir does, what clinical studies show about healing times, how to apply it correctly, how to stay comfortable during an outbreak, what can affect treatment, and when oral antiviral treatment may be considered. The aim is to help you understand what to expect and use aciclovir at the right time and in the right way.
Key things to know
- In clinical trials, topical aciclovir cream shortened healing time by roughly half a day to one day compared with placebo.
- The benefit is generally modest, with studies reporting around half a day to one day faster healing on average.
- Starting treatment as early as possible, ideally when you first notice tingling or other early symptoms, is generally recommended.
- Apply the cream 5 times a day, roughly every 4 hours during waking hours, for 5 days, unless your product information or healthcare professional advises otherwise.
How Aciclovir Cream Works
Aciclovir 5% cream contains an antiviral medicine used to treat herpes simplex virus infections, including the virus that causes cold sores. When applied to the affected area, it interferes with viral DNA replication, which may help limit the virus from multiplying in the treated area.
Aciclovir does not remove herpes simplex virus from the body. The virus can remain dormant between outbreaks, which means cold sores can return in the future.
Aciclovir is available in different formulations, including cream and tablets. Topical cream is applied directly to the affected area, while oral aciclovir works throughout the body. This difference is one reason oral antivirals may be considered in some people with frequent, severe, or extensive outbreaks.
What the Evidence Actually Shows
The clinical trials behind topical aciclovir cream included more than 1,300 adults with recurrent cold sores across two large studies. They reported average healing times of approximately 4.6 days with aciclovir cream compared with approximately 5.2 days with placebo, giving a difference of around half a day.
Some people may notice their symptoms improving during treatment, but individual results can vary. Patient reported pain duration also showed a modest improvement in these studies. Evidence reviews have generally described the benefit of topical antiviral treatment for cold sores as modest rather than dramatic, while recommending that treatment is started as early as possible during an outbreak.
This is more modest than claims suggesting that aciclovir cream can reduce healing time by several days. The available clinical evidence supports a smaller average benefit. Even a half day to one day reduction may be useful, particularly when discomfort is also reduced, but it is important to understand what the evidence actually shows.
Setting Realistic Expectations
Aciclovir cream is not expected to make a cold sore disappear overnight, and it does not cure the underlying herpes infection. Instead, it may modestly reduce how long the active outbreak lasts and may help with discomfort.
Using the cream consistently for the recommended course and starting treatment early may give you the best chance of getting the expected benefit. However, cold sores can still take several days to heal, even when treatment is started promptly.
Does Starting Early Make a Bigger Difference?
Starting treatment when you first notice tingling, itching, burning, or other early symptoms is generally recommended. Ideally, this is before a visible blister develops.
Starting early may give the treatment a better opportunity to limit the outbreak before it becomes fully established. However, this does not guarantee that a cold sore will be prevented or disappear quickly.
If you regularly experience cold sores, keeping your treatment available can make it easier to start promptly when you recognise the early signs.
How to Apply Aciclovir Cream Correctly
- Apply 5 times a day, spacing applications by about four hours during waking hours.
- Continue treatment for 5 days. If the cold sore has not healed after 5 days, follow the product information or speak to a pharmacist.
- Wash your hands before and after applying the cream. Use a clean finger or cotton bud to apply it.
- Apply the cream to the affected area, including the edges where new blisters may appear.
- Start using aciclovir cream as soon as possible after symptoms begin, ideally when you first notice tingling, itching, or other early symptoms, rather than waiting for a visible blister.
Using the cream correctly and consistently is important. Missing applications or stopping treatment early may reduce the benefit you get from treatment.
Managing Comfort Alongside Treatment
- Avoid touching or picking the cold sore. This can help reduce the risk of spreading the infection through direct contact and may also prevent further irritation.
- A cold compress may help relieve discomfort. Apply it gently rather than pressing firmly against the affected area.
- Simple over the counter pain relief, such as paracetamol, may help with discomfort if it is suitable for you.
- If sunlight tends to trigger your cold sores, consider using lip protection with an appropriate sun protection factor.
These measures may make the area more comfortable while the cold sore heals. They do not replace aciclovir treatment, but they can be useful alongside it.
What Affects How Well It Works
- How soon you start treatment after noticing the first symptoms.
- How consistently you apply the cream throughout the day.
- Your immune system and general health, which can affect how your body responds to an outbreak.
- Whether you have frequent or severe outbreaks. If this is happening regularly, speak to a prescriber about whether oral antiviral treatment may be appropriate.
When Oral Treatment Might Suit You Better
If you experience cold sores frequently, for example, more than six outbreaks a year, or if topical cream is not providing enough relief, it may be worth discussing oral antiviral treatment with a prescriber. Options such as oral aciclovir or valaciclovir can be used to treat certain herpes virus infections and work throughout the body rather than only at the site where the cream is applied.
For people with frequent recurrences, a prescriber may also consider suppressive antiviral treatment to help reduce how often outbreaks occur. This is different from treating an individual cold sore and is not usually needed for occasional outbreaks.
Aciclovir can also be used to treat infections such as chickenpox and shingles, but this page focuses on its use for cold sores.
Oral treatment is not automatically better for everyone. The most suitable option depends on factors such as how often you get cold sores, how severe your outbreaks are, and your medical history. A prescriber can help you decide whether topical cream or an oral antiviral is more appropriate for you.
Ready to start? Start your free online consultation to discuss whether cream or tablets suit your situation best.
Available Treatments
| Treatment | Price |
|---|---|
| Aciclovir Tablets | From £12.99 |
| Aciclovir 5% Cream | From £8.99 |
| Valaciclovir | From £18.99 |
| Valtrex | From £34.99 |
Prices update live and may change.
Medical Disclaimer
This page provides general information about aciclovir cream and the clinical evidence on its effectiveness. It is not a substitute for personalised medical advice, diagnosis, or treatment.
Individual results can vary, and the results seen in clinical studies may not be the same for everyone. If your cold sore is not improving after a few days of treatment, speak to a doctor or pharmacist. Seek medical advice if your symptoms are severe, getting worse, or not improving as expected.
If you develop signs of an allergic reaction, such as swelling or a rash, seek medical advice promptly. Tell your doctor or pharmacist about any other medicines you are taking, including over the counter medicines and supplements, so they can check whether aciclovir cream is suitable for you.
