4 Ways to Get the Most From Cold Sore Treatment

5 min read

Cold sores are uncomfortable enough without getting the treatment wrong. These four practical tips will help you get the most from antiviral treatment and recover as quickly as possible.

Medically Reviewed By:

Ana Carolina Goncalves

GPHC Number 2088658

Written By:

Rehma Gill

GPHC Number 2225869

Updated: 13 May 2026

Cold sores affect a significant proportion of the UK population. The World Health Organization estimates that around 67% of people globally carry herpes simplex virus type 1 (HSV-1), the virus responsible for cold sores on the lips and face.¹ For many, outbreaks are infrequent. For others, they can occur several times a year, triggered by sunlight, stress, illness, or hormonal changes.²

Antiviral cold sore treatment can shorten the duration of an outbreak and reduce the severity of symptoms, but only when it's used correctly. The difference between a cold sore that clears up quickly and one that lingers often comes down to a few practical decisions. Here are four ways to get the most from cold sore treatment.

Tip 1: Start Treatment at the First Sign of Tingling

The most important factor in cold sore treatment is timing. Antiviral creams such as aciclovir 5% cream are most effective during the prodromal stage - the brief window, usually lasting a few hours to a day or two, when you feel a tingling, itching, or burning sensation before any visible blister forms.

During this stage, the herpes simplex virus has reactivated in your nerve cells and is beginning to replicate. Applying antiviral cream at this point can interrupt that process and reduce the severity of the outbreak.⁴ Once blisters have fully formed, treatment can still help limit symptoms, but the window of maximum effectiveness has passed. Starting within the first 24 hours gives you the best chance of a faster recovery.

If you experience cold sores regularly, keeping a tube of aciclovir cream to hand means you can act as soon as you recognise that familiar warning sensation. This alone makes a bigger difference than almost anything else you can do.

Tip 2: Apply the Cream Correctly - and Often Enough

Aciclovir cold sore cream should be applied five times a day, roughly every four hours.³ A practical schedule for most people could like like: 7am, 11am, 3pm, 7pm, and 11pm. Sticking to this frequency is important because antiviral creams need to maintain consistent contact with the affected skin to remain effective. Any missed doses can reduce how well they work.

When applying, use a clean fingertip or cotton bud to dab a thin layer of cream over the cold sore and the skin immediately around it. Do not rub it in vigorously. Gentle dabbing reduces the risk of spreading the virus to surrounding skin.⁶ Wash your hands thoroughly before and after each application to prevent passing the virus to other areas of your face or to other people.

The standard course is five days. If the cold sore hasn't healed after five days, you can continue for a further five days. If it hasn't cleared after a total of ten days, you should stop using the cream and speak to your doctor or pharmacist.

Tip 3: Protect the Area From Sun Exposure

Ultraviolet (UV) light is one of the most well-documented triggers for cold sore recurrence. Sun exposure can reactivate the herpes simplex virus in nerve cells, bringing on a new outbreak. This is why cold sores often flare up during summer months or after a sunny holiday.⁵

This has two implications. First, if you're managing an active outbreak, try to avoid direct sun exposure on the affected area as much as possible. Do not apply sunscreen or lip balm directly over aciclovir cream on the cold sore itself while you're using treatment.³ Second, once the cold sore has fully healed, wearing an SPF 15 or above lip balm when outdoors in sunny weather can help reduce the chance of UV-triggered recurrences going forward.

The NHS recommends using sunblock lip balm if you're prone to cold sores and planning to spend time outdoors in the sun.² It's a simple, low-effort step that can reduce outbreak frequency for many people.

Tip 4: Avoid Spreading the Virus While You Heal

Cold sores are contagious from the moment you first notice tingling, right until the scab has fully healed and the skin underneath looks normal again.² The virus is most infectious in the 24 hours after blisters first form and when blisters burst, so this is when extra care is most important.

During an active outbreak, avoid kissing anyone - especially young children - and do not share items that come into contact with your mouth, such as cups, cutlery, straws, lip balm, or face towels. Touching the cold sore and then touching other areas of your face can spread HSV to new sites. Washing your hands after every application of cream significantly reduces this risk.

It's also worth being aware that stress, fatigue and illness can each reduce the immune response that keeps the virus dormant between outbreaks. Keeping on top of sleep and general health won't prevent cold sores entirely, but it can reduce how often they flare up. If you're finding outbreaks frequent or particularly troublesome, speak to your pharmacist about your options, including whether antiviral tablets might be more appropriate for you.

Frequently Asked Questions

When should I start using cold sore treatment?

As soon as you notice the first signs of a cold sore. This will typically be a tingling, itching or burning sensation on or around the lips. Antiviral creams such as aciclovir work best during this early prodromal stage, before any blisters appear. Starting treatment within the first 24 hours gives the best chance of reducing severity and shortening healing time.⁴

How long does a cold sore last with treatment?

With antiviral treatment started promptly, a cold sore typically heals within five to seven days. Without treatment, most cold sores resolve within seven to ten days. Treatment also tends to reduce the size of the blister and the level of discomfort during the outbreak.

How often should I apply cold sore cream?

Aciclovir 5% cold sore cream should be applied five times a day, every four hours. A suggested schedule is 7am, 11am, 3pm, 7pm, and 11pm.³ The standard course is five days, which can be extended to ten days if the sore hasn't healed.

Can I use cold sore cream on genital herpes?

No. Aciclovir cream licensed for cold sores is intended for use on the lips and face only. Genital herpes requires different treatment. If you think you have genital herpes, speak to your GP or visit a sexual health clinic for advice. Genital herpes treatment is also available through Pharmica.

Does cold sore cream still work once a blister has appeared?

It can help reduce symptoms and prevent blisters from worsening, but it is significantly less effective once blisters have fully formed. The best results come from applying it at the earliest tingling stage, before any visible blister appears.⁴

This article is intended for informational purposes only and does not replace professional medical advice. Always read the patient information leaflet supplied with your medication and speak to a healthcare professional if you have specific concerns.