What Is Aciclovir Cold Sore Cream and How Can It Help?

Cold sores are one of those things that always seem to appear at the worst possible moment — before a big event, when you're run down, or right after a bout of illness. They're caused by the herpes simplex virus type 1 (HSV-1), which lies dormant in nerve tissue and reactivates when your immune system is under pressure. Aciclovir cold sore cream is a clinically proven antiviral treatment that targets the virus directly, helping to shorten the duration of an outbreak and ease discomfort. Numark Cold Sore Cream contains aciclovir 5% w/w and is available over the counter without a prescription, making it easy to treat a cold sore quickly. You can find it alongside other creams and ointments at Cured Pharmacy.

Cold sores typically go through several stages — tingling, blistering, weeping, and crusting — and the earlier you start treatment, the better the outcome. The NHS advises that antiviral creams like aciclovir are most effective when applied at the very first sign of a cold sore, ideally during the tingling or itching phase before a blister even forms.

How Does Numark Cold Sore Cream Work?

Aciclovir belongs to a class of medicines called nucleoside analogues. It works by interfering with the herpes simplex virus's ability to replicate inside your skin cells. Here's how the process unfolds:

Aciclovir is absorbed into cells infected by the herpes simplex virus.
Inside infected cells, a viral enzyme called thymidine kinase converts aciclovir into its active form, aciclovir triphosphate.
Aciclovir triphosphate then blocks the viral enzyme DNA polymerase, which the virus needs to copy its DNA.
Without the ability to replicate, the virus cannot spread further, and the outbreak begins to resolve.

Because this activation process relies on a viral enzyme, aciclovir acts selectively on infected cells and has very little effect on healthy surrounding tissue. That's what makes it a well-tolerated topical treatment for most people.

Who Is Numark Cold Sore Cream Suitable For?

This cream is suitable for most adults and young people aged 12 and over who experience recurrent cold sores on the lips or face. It is an over-the-counter medicine, so you don't need a prescription to buy it. That said, it's not appropriate for everyone. It is suitable for:

Adults and adolescents aged 12 years and over
People experiencing the early signs of a cold sore (tingling, itching, or redness)
Those with recurrent herpes labialis (cold sores on the lips or around the mouth)
People looking for a cost-effective alternative to branded aciclovir creams

It is not suitable for use on genital herpes, inside the mouth, near the eyes, or on mucous membranes. If you're unsure whether this product is right for you, speak to a pharmacist before use.

How Does Numark Cold Sore Cream Compare to Other Cold Sore Treatments?

Feature	Numark Aciclovir Cold Sore Cream	Zovirax Cold Sore Cream
Active ingredient	Aciclovir 5%	Aciclovir 5%
Prescription required	No (OTC)	No (OTC)
Typical price	£4.49	£6.00–£8.00+
Application frequency	5 times daily for 5 days	5 times daily for 5 days

Is Numark Cold Sore Cream Safe to Store and Use Long Term?

Numark Cold Sore Cream should be stored below 25°C, away from direct heat and sunlight, and kept out of the reach of children. Do not use the cream after the expiry date printed on the packaging. Once opened, the tube should be used within the period indicated on the label. If you experience frequent cold sore outbreaks — more than six per year — it's worth speaking to your GP, as oral antiviral therapy may be more appropriate for suppressive treatment. For everyday skin health between outbreaks, you might also find useful products in our skin care collection.

This product is a medicine. Speak to your doctor or pharmacist before using if you have an underlying medical condition or are taking other medicines.

Numark Cold Sore Cream - Aciclovir specifications

Treatment category	Antiviral / Cold sore treatment
Active ingredient	Aciclovir 5% w/w
Mechanism of action	Inhibits herpes simplex virus DNA polymerase, preventing viral replication
Effective against	Herpes simplex virus type 1 (HSV-1) — cold sores on lips and face
Suitable for	Adults and adolescents aged 12 years and over
Strengths	5% w/w
Preparation	Topical cream
Route of administration	Topical (skin surface only)
UK classification	Pharmacy (P) medicine
Drug class	Nucleoside analogue antiviral
Pack size	2g tube

Specifications of Numark Cold Sore Cream - Aciclovir

What Is Numark Cold Sore Cream and What Is It Used For?

Numark Cold Sore Cream is a topical antiviral medicine containing aciclovir 5% w/w. It is used to treat cold sores — small, fluid-filled blisters that typically appear on or around the lips and are caused by the herpes simplex virus (HSV-1). Cold sores are extremely common in the UK; the NHS estimates that around two-thirds of people under 50 carry the virus, though not everyone develops visible sores. The cream does not cure the underlying viral infection, but it can significantly reduce the severity and duration of an outbreak, particularly when applied early. It is classified as a Pharmacy (P) medicine and is available without a prescription from registered pharmacies.

What Do You Need to Know Before Using Numark Cold Sore Cream?

Before applying this cream, read the following carefully. There are situations where this product may not be appropriate for you.

Do not use this cream if you:

Are allergic to aciclovir, valaciclovir, propylene glycol, or any other ingredient in the cream
Have a severely weakened immune system (e.g. due to HIV, chemotherapy, or organ transplant) — seek medical advice first
Are under 12 years of age — use only under medical supervision
Have cold sores inside the mouth, near the eyes, or on the genitals — this cream is not suitable for those areas

Warnings and precautions:

Avoid contact with eyes, mouth, and mucous membranes
Do not apply to broken or inflamed skin beyond the cold sore itself
If you are pregnant or breastfeeding, consult your doctor or pharmacist before use
Cold sores are contagious — avoid kissing or sharing utensils during an outbreak
If your cold sore has not improved after 10 days, see your GP

Drug interactions:

No clinically significant interactions are known at topical doses
If you are taking oral antiviral medicines, inform your pharmacist before using this cream

How Should You Use Numark Cold Sore Cream?

Timing is everything with cold sore treatment. Apply the cream as soon as you notice the first warning signs — tingling, itching, or redness — before a blister has fully formed. This gives the aciclovir the best chance of limiting the outbreak. If you're also managing other skin concerns, our first aid collection has a range of products that may help with minor skin irritation.

Wash your hands thoroughly before and after applying the cream.
Using a clean fingertip or cotton bud, apply a thin layer of cream to the affected area.
Gently smooth the cream over the cold sore — do not rub vigorously.
Apply five times a day, approximately every four hours (you may skip the night-time dose if needed).
Continue treatment for five days. If the sore has not healed, continue for up to ten days.
Do not cover the treated area with a plaster or dressing unless advised by a healthcare professional.

Indication	Age Group	Dose	Frequency
Cold sore (herpes labialis)	Adults and adolescents (12+)	Small amount applied to affected area	5 times daily for 5–10 days
Cold sore (herpes labialis)	Under 12 years	Not recommended without medical advice	—

What Are the Possible Side Effects of Numark Cold Sore Cream?

Like all medicines, Numark Cold Sore Cream can cause side effects, although not everyone experiences them. Most side effects are mild and localised to the area of application.

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

Mild burning or stinging sensation at the application site
Itching or tingling of the skin
Temporary skin dryness or flaking

Less common side effects (may affect up to 1 in 100 people):

Skin redness or mild rash around the treated area
Contact dermatitis (allergic skin reaction) — stop use and seek advice if this occurs
Swelling or peeling of the skin

If you experience a severe allergic reaction — including swelling of the face, lips, or throat, difficulty breathing, or widespread rash — stop using the cream immediately and seek emergency medical attention. This type of reaction is rare but serious.

How Should You Store Numark Cold Sore Cream?

Correct storage helps maintain the effectiveness of the cream throughout its shelf life. Follow these guidelines:

Store below 25°C in a cool, dry place
Do not refrigerate or freeze
Keep the tube tightly closed when not in use
Keep out of the reach and sight of children
Do not use after the expiry date printed on the tube and carton
Do not dispose of medicines via wastewater or household waste — return unused medicines to your pharmacy

If you're looking for other treatments to support your health during a cold sore outbreak — such as immune-supporting supplements — browse our vitamins and supplements range for options that may help support general wellbeing.

References

https://www.nhs.uk/conditions/cold-sores/
https://www.nhs.uk/medicines/aciclovir/
https://www.nhs.uk/conditions/cold-sores/treatment/
https://www.nhs.uk/conditions/herpes-simplex-eye-infections/
https://bnf.nice.org.uk/drugs/aciclovir/

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Written and reviewed by our qualified team

Your safety and success are our highest priorities. Our medical team rigorously evaluates every product and piece of advice we provide, ensuring you receive only the most effective, science-backed solutions available.

Frequently Asked Questions

Where can I buy Numark Aciclovir Cold Sore Cream online in the UK?

You can buy Numark Aciclovir Cold Sore Cream directly from Cured Pharmacy, a GPhC-registered UK online pharmacy, for just £4.49. It is available without a prescription as an over-the-counter Pharmacy (P) medicine. Simply add it to your basket and it will be dispatched promptly to your door.

How does aciclovir cold sore cream work in the body?

Aciclovir is a nucleoside analogue antiviral that is selectively activated inside cells infected by the herpes simplex virus. Once activated by a viral enzyme called thymidine kinase, it blocks the virus's DNA polymerase, stopping it from replicating. This limits the spread of the virus and helps the cold sore heal more quickly.

How do I apply Numark Cold Sore Cream step by step?

Wash your hands before and after application. Apply a small amount of cream to the cold sore and the area immediately surrounding it using a clean fingertip or cotton bud. Repeat five times a day, roughly every four hours, for five days — or up to ten days if the sore has not fully healed.

When is the best time to start using aciclovir cold sore cream?

The earlier you start, the better. Apply the cream at the very first sign of a cold sore — typically a tingling, itching, or burning sensation — before a blister has formed. Starting treatment during this prodromal phase gives aciclovir the best chance of reducing the severity and duration of the outbreak. Waiting until a blister is fully developed reduces its effectiveness.

How long does it take for aciclovir cold sore cream to work?

Most people notice improvement within five days of starting treatment, particularly if the cream is applied early. Some outbreaks may take up to ten days to fully resolve. If your cold sore has not improved after ten days of consistent use, you should see your GP, as a different treatment approach may be needed.

What are the side effects of Numark Cold Sore Cream?

The most common side effects are mild and localised, including a brief burning or stinging sensation, itching, and skin dryness at the application site. Less commonly, some people experience a mild rash or contact dermatitis. If you develop signs of a severe allergic reaction — such as facial swelling or difficulty breathing — stop use immediately and seek emergency medical help.

How do I manage side effects of Numark Cold Sore Cream?

Mild stinging or dryness usually settles on its own and does not require you to stop treatment. If skin irritation is bothersome, try applying the cream with a cotton bud rather than your fingertip to reduce friction. If you develop a rash or signs of an allergic reaction, discontinue use and speak to your pharmacist or GP promptly.

Who is eligible to use Numark Cold Sore Cream?

This cream is suitable for adults and adolescents aged 12 years and over who have cold sores on the lips or face caused by the herpes simplex virus. It is not suitable for children under 12 without medical supervision, and it should not be used on genital herpes, inside the mouth, or near the eyes. People with severely weakened immune systems should seek medical advice before use.

Can I use Numark Cold Sore Cream if I am pregnant or breastfeeding?

If you are pregnant or breastfeeding, you should speak to your doctor or pharmacist before using aciclovir cold sore cream. Although topical absorption into the bloodstream is minimal, it is always best to seek professional guidance during pregnancy and breastfeeding before using any medicine, even one applied to the skin.

What happens if I miss a dose of Numark Cold Sore Cream?

If you forget to apply the cream at one of your scheduled times, apply it as soon as you remember and then continue with your regular schedule. Do not apply a double amount to make up for a missed application. Consistency is important — try to apply the cream five times throughout the day at roughly equal intervals.

Is Numark Aciclovir Cold Sore Cream the same as Zovirax?

Yes, both products contain the same active ingredient — aciclovir 5% w/w — and work in exactly the same way. Numark is a pharmacy own-brand alternative to Zovirax that offers identical clinical efficacy at a significantly lower price point. The main difference is the brand name and packaging, not the medicine itself.

Can children use Numark Cold Sore Cream?

Numark Cold Sore Cream is not recommended for children under 12 years of age without medical advice. If your child develops a cold sore, speak to a pharmacist or GP before applying any antiviral cream. For general guidance on children's health products, you may find our baby and toddler collection a useful starting point for age-appropriate options.

What are the alternatives to aciclovir cold sore cream?

Alternatives include other topical antivirals such as penciclovir cream (Vectavir), which is applied every two hours while awake. For people with frequent or severe outbreaks, a GP may prescribe oral aciclovir or valaciclovir as suppressive therapy. Non-antiviral options such as cold sore patches or lip balms with SPF can help protect the area but do not treat the virus itself.

How long can you use aciclovir cold sore cream for?

Each course of treatment should last five days, extended to a maximum of ten days if the cold sore has not fully healed. This cream is intended for episodic treatment of individual outbreaks, not for continuous long-term use. If you experience more than six cold sore outbreaks per year, speak to your GP about whether suppressive antiviral therapy might be appropriate for you.

What does the latest research say about aciclovir for cold sores?

Aciclovir has been used clinically for decades and remains a well-established first-line treatment for herpes simplex infections. Published clinical evidence consistently shows that topical aciclovir, when applied early, reduces the duration of cold sore episodes and associated pain. The NHS and BNF continue to recommend it as an effective over-the-counter option for recurrent herpes labialis. For broader skin health support between outbreaks, explore our skin care collection.

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