Cold Sore Ointment (Salva vid Munsår)

What Is Cold Sore Ointment and What Is It Used For?

Cold sore ointment is a topical medication applied to the lips and surrounding skin to treat cold sores caused by herpes simplex virus type 1 (HSV-1). It contains an active ingredient (most commonly docosanol, aciclovir or penciclovir) that either blocks the virus from entering healthy cells or stops it from replicating inside infected cells. The result is faster healing, reduced pain and less viral shedding.

Cold sores – also known as fever blisters or herpes labialis – are small, painful, fluid-filled blisters that typically appear on or around the lips. They are caused by the herpes simplex virus, usually type 1 (HSV-1). According to the World Health Organization, an estimated 3.7 billion people under the age of 50 worldwide are living with HSV-1 infection, and around one-third of them experience recurrent symptomatic outbreaks. Cold sore ointments (in Swedish, salva vid munsår) are the most accessible first-line treatment for these outbreaks and are available over-the-counter in most countries.

The term "cold sore ointment" refers to a category of products rather than a single medicine. Each product contains one or more active ingredients designed to shorten the duration of a cold sore, alleviate discomfort, and reduce the risk of spreading the virus to other people or other parts of the body. Unlike oral antivirals such as aciclovir tablets or valacyclovir, topical cold sore ointments deliver the active substance directly to the site of infection, resulting in minimal systemic absorption and an excellent safety profile.

The main active ingredients found in evidence-based cold sore ointments include:

• Docosanol 10%: A saturated 22-carbon aliphatic alcohol that inhibits the fusion between the viral envelope and the human cell membrane, preventing the virus from entering healthy cells. It is the first and only OTC active ingredient approved by the U.S. Food and Drug Administration (FDA) for cold sore treatment, approved in 2000.
• Aciclovir 5% cream: A nucleoside analogue antiviral that is phosphorylated by viral thymidine kinase and inhibits viral DNA polymerase, stopping viral replication. Available OTC in many European countries (including Sweden, the UK and Germany) but still prescription-only in some jurisdictions.
• Penciclovir 1% cream: A close structural relative of aciclovir with a longer intracellular half-life. Marketed under the brand name Denavir in some countries and available over-the-counter in others.
• Hydrocolloid patches: Non-medicated barrier dressings (such as Compeed Cold Sore Patch) that cover the lesion, absorb exudate, reduce pain and conceal the sore. These support healing but have no direct antiviral effect.
• Combination and symptomatic products: Some ointments contain zinc oxide, lidocaine, benzocaine, lysine or tea tree oil to relieve burning, itching and inflammation. The evidence base for these ingredients is weaker than for docosanol, aciclovir and penciclovir.

Cold sore ointments are intended for the treatment of recurrent cold sores in healthy adults and adolescents (typically from age 12 upwards, depending on product and jurisdiction). They are not suitable as a standalone treatment for primary HSV-1 infection in young children, severe or widespread eruptions, infections in immunocompromised patients, or herpes infections of the eye or genitals. In those situations, systemic antiviral therapy (oral tablets or intravenous infusion) prescribed by a doctor is the appropriate approach.

What Should You Know Before Using Cold Sore Ointment?

Before using a cold sore ointment, check that you are treating an actual cold sore on the lips or perioral skin and not a different condition. Do not use inside the mouth, nose, eyes or on the genitals. Wash your hands before and after application. Consult a doctor before use if you are pregnant, breastfeeding, immunocompromised, under 12 years of age, or if outbreaks are unusually frequent, severe, or long-lasting.

Although cold sore ointments have a very favourable safety profile, they are still medicines and should be used correctly. Taking a moment to review the key considerations below helps ensure that treatment is both effective and safe for you. If you have any doubts about whether an OTC cold sore ointment is right for your situation, speak to a pharmacist or physician before starting treatment.

Contraindications

You should not use a cold sore ointment if you have a known hypersensitivity (allergy) to the active ingredient, to related substances (for example, valacyclovir if you are allergic to aciclovir; famciclovir if you are allergic to penciclovir), or to any of the excipients such as propylene glycol, cetostearyl alcohol or poloxamer 407. Read the list of ingredients on the package leaflet carefully if you have a history of contact dermatitis to cosmetic or pharmaceutical excipients.

Ointments designed for the external lip area should not be applied to mucous membranes of the mouth, nose or genitals, and should not come into contact with the eye. If the ointment is accidentally applied inside the mouth, the small amount ingested is unlikely to cause harm, but swallowing large quantities deliberately should be avoided. If ointment enters the eye, rinse immediately with plenty of lukewarm water and seek medical advice if irritation persists.

Warnings and Precautions

Talk to your doctor or pharmacist before using cold sore ointment if any of the following applies to you:

• Immunocompromised patients: People living with HIV/AIDS, patients receiving chemotherapy or long-term high-dose corticosteroids, and organ transplant recipients can develop unusually severe, atypical or persistent cold sores. Topical treatment alone may not be sufficient, and systemic antivirals under medical supervision are often required.
• Eczema herpeticum risk: People with atopic dermatitis (eczema) can rarely develop eczema herpeticum, a potentially serious disseminated HSV infection. Widespread, painful, weeping lesions outside the normal cold sore area require urgent medical assessment rather than OTC treatment.
• First-ever outbreak: Primary HSV-1 infection (a person's first-ever cold sore) is often more extensive and painful than recurrent outbreaks and may be accompanied by fever, swollen lymph nodes and difficulty eating. In such cases, a doctor may prescribe oral antivirals, which are more effective than topical treatment alone.
• Frequent recurrences: If you experience six or more episodes per year, suppressive oral therapy with aciclovir or valacyclovir may be more effective than treating each individual outbreak topically. A doctor can advise on this option.
• Lesions that do not heal: A cold sore that does not heal within 10–14 days, that is unusually painful, or that recurs in exactly the same spot every time, should be assessed by a healthcare professional to exclude other causes such as impetigo, angular cheilitis, squamous cell carcinoma of the lip or drug hypersensitivity reactions.

Pregnancy and Breastfeeding

Topical cold sore ointments are generally considered low-risk during pregnancy and breastfeeding because systemic absorption through intact or mildly eroded skin is minimal. However, you should always consult a doctor, midwife or pharmacist before starting any new medication during pregnancy or while breastfeeding.

Aciclovir has the most robust safety data in pregnancy of all the active ingredients found in cold sore ointments. The international Acyclovir Pregnancy Registry, which monitored more than 1,000 pregnancies exposed to systemic aciclovir, did not find an increased risk of birth defects compared with the general population. Topical exposure is much lower than systemic exposure and is therefore expected to carry an even smaller risk. Data for topical docosanol and penciclovir in pregnancy are more limited, but no specific teratogenic signal has been identified. If you are breastfeeding, avoid applying the ointment to the nipple or areolar area; wash your hands thoroughly after applying to the lips before handling your baby.

Use in Children

Most cold sore ointments are licensed for use from age 12 and above. Some products (particularly aciclovir 5% cream) can be used from younger ages under medical advice. Do not use cold sore ointment on a child under 12 without first speaking to a doctor or pharmacist. Primary HSV-1 infections in young children often present as gingivostomatitis (painful inflammation of the gums and mouth lining) and require different treatment than recurrent cold sores.

Driving and Using Machines

Cold sore ointments applied topically do not affect your ability to drive or operate machinery. Systemic absorption is minimal and no central nervous system effects are expected. You can go about your normal daily activities during treatment.

How Does Cold Sore Ointment Interact with Other Drugs?

Topical cold sore ointments have very few drug interactions because systemic absorption is minimal. The most relevant interactions are local: avoid applying other medicated creams, cosmetics or lip products to the same area at the same time, and do not combine two different antiviral ointments without medical advice.

Because cold sore ointments are applied externally and reach only very low concentrations in the bloodstream, clinically significant systemic drug interactions are rare. This is one of the key safety advantages of topical therapy compared with oral antivirals. However, some local interactions at the site of application are possible and worth considering.

The following table summarises the most important interactions to be aware of:

Major Interactions

The most clinically important interaction to avoid is the combination of a cold sore ointment with a topical corticosteroid applied to the same area. Corticosteroids suppress the local immune response and can lead to larger, more persistent or more frequent outbreaks, as well as increasing the risk of bacterial superinfection. If you have been prescribed a corticosteroid cream for another skin condition on your face, ask your doctor how to manage a concurrent cold sore before applying both products to overlapping areas.

A second important consideration is the use of two different antiviral ointments at the same time. There is no evidence that combining, for example, docosanol and aciclovir speeds up healing compared with either product used alone. Switching between products during a single outbreak may also make it harder to follow the correct dosing schedule. Choose one evidence-based product and use it consistently for the recommended duration.

Minor Interactions

Minor interactions include the use of cosmetic lip balms, lipsticks or lip glosses during an active outbreak. These products can physically dilute the antiviral ointment and can also become contaminated with the virus, potentially re-infecting you after the outbreak has healed. Dermatologists therefore recommend setting cosmetic lip products aside during an active cold sore and replacing any lipstick or balm that was used on the lips during the outbreak once it has fully healed.

Tell your pharmacist or doctor about all medications, vitamins, herbal remedies and skincare products you are using, even if they seem unrelated. This information helps them identify any interactions specific to your situation and recommend the most appropriate cold sore treatment for you.

What Is the Correct Dosage of Cold Sore Ointment?

The standard dosing varies by active ingredient. Docosanol 10% cream is applied 5 times a day until the sore is healed (maximum 10 days). Aciclovir 5% cream is applied 5 times a day at roughly 4-hour intervals for 4–5 days, up to a maximum of 10 days. Penciclovir 1% cream is applied every 2 hours during waking hours for 4 days. In all cases, start treatment at the very first sign of tingling, itching or burning.

The effectiveness of a cold sore ointment depends heavily on when you start using it. Clinical trials consistently show that the earliest phase of a cold sore – the prodromal phase, characterised by tingling, itching or burning before any blister is visible – is the most responsive to treatment. Starting treatment after the blister has already fully formed still helps, but the reduction in healing time is smaller. Always read the package leaflet of the specific product you have purchased, as dosing instructions can vary slightly between manufacturers.

Adult Dosage

Children

Most cold sore ointments are licensed for use from 12 years of age. Aciclovir 5% cream is one of the few products that can be used from an earlier age under the supervision of a doctor or pharmacist. Children who experience their first cold sore should be assessed by a healthcare provider because primary HSV-1 infection in children is frequently more severe than the recurrent lip-based outbreak typically seen in adolescents and adults, and often requires a different treatment approach including possibly oral antivirals, fluids and pain relief.

Elderly Patients

No dose adjustment of topical cold sore ointment is needed for elderly patients, because systemic absorption is minimal and the kidneys and liver are not required to clear significant amounts of drug. Older adults may, however, have reduced skin barrier function, be more prone to irritation, and take more concomitant medications. If you are over 65 and are using multiple topical or systemic medicines, check with a pharmacist before starting an OTC cold sore ointment.

Missed Dose

If you forget to apply the ointment at a scheduled time, apply it as soon as you remember, then continue with your normal schedule. Do not apply a double dose or use more ointment than recommended to make up for a missed application. Consistent use at regular intervals is more important than the absolute number of applications per day, so try to space applications evenly across your waking hours.

Overdose

Accidental ingestion of a small amount of cold sore ointment – for example, if a small child licks a tube – is unlikely to cause serious harm, but the person should be observed for nausea, vomiting or diarrhoea. If a large amount has been swallowed, or if symptoms appear, contact your national poison control centre or seek medical advice. Applying a thicker-than-recommended layer of ointment to the skin does not improve efficacy and may increase local irritation; wipe away the excess gently with a tissue if this occurs.

What Are the Side Effects of Cold Sore Ointment?

Topical cold sore ointments are very well tolerated. The most common side effects are mild and localised to the application site: temporary burning, stinging, dryness or flaking of the skin. Serious adverse effects are rare. Stop using the ointment and seek medical advice if you develop severe irritation, spreading rash, swelling, or any sign of allergic reaction.

Because only a very small amount of drug is absorbed systemically from the skin, topical antivirals have a far better safety profile than their oral counterparts. Most side effects, when they occur, are mild, reversible and limited to the area where the ointment is applied. Clinical trials of docosanol, aciclovir and penciclovir have found that the rate of adverse events is similar to that seen with placebo cream, indicating that most reactions are caused by the excipients (the non-active components of the cream) rather than the active substance itself.

Local Skin Reactions

By far the most common adverse event with cold sore ointments is a transient burning, stinging or tingling sensation immediately after application. This usually lasts only a few minutes and tends to decrease with repeated use. If the sensation is severe, persistent or accompanied by increasing redness and swelling, you may have developed an irritant or allergic reaction to one of the ingredients. Stop use and consider switching to a product with a different active ingredient or excipient profile.

Contact dermatitis is an uncommon but well-documented reaction to topical cold sore products. It can be caused either by the active ingredient itself or, more often, by excipients such as propylene glycol, cetostearyl alcohol or preservatives. Patch testing performed by a dermatologist can identify the specific allergen if repeated reactions occur. In most cases, simply switching to a different brand resolves the problem.

Systemic Side Effects

Systemic side effects from properly applied topical cold sore ointments are extremely uncommon. Bloodstream concentrations of aciclovir after application of 5% cream are typically below the limit of detection in pharmacokinetic studies, and docosanol and penciclovir show similarly negligible absorption. As a result, the side effects commonly associated with oral antivirals – such as headache, nausea, diarrhoea, fatigue and, very rarely, kidney or neurological effects – are essentially not seen with topical use at recommended doses.

Reporting Side Effects

If you experience any side effects, including those not listed here, talk to your pharmacist or doctor. You can also report side effects directly to your national medicines regulatory authority (for example, the FDA MedWatch programme in the United States, the Yellow Card scheme in the United Kingdom, or EudraVigilance in the European Economic Area). Reporting helps improve knowledge about the safety of medications and protects other users.

How Should You Store Cold Sore Ointment?

Store cold sore ointment at room temperature below 25°C (77°F), away from direct sunlight and moisture. Keep the tube tightly closed and out of the sight and reach of children. Do not use after the expiry date printed on the carton, and discard the tube after the in-use shelf life (typically 3 months from first opening).

Correct storage helps maintain both the potency of the active ingredient and the safety of the formulation. Heat, humidity, direct sunlight and contamination from repeated contact with the fingers can all reduce the effectiveness of the product or introduce microbes into the tube. The following general principles apply to all common cold sore ointments.

Keep the tube in its original carton to protect it from light, and store it in a cool, dry place. A bedroom drawer or kitchen cupboard is generally more appropriate than a bathroom cabinet, because the temperature and humidity in bathrooms fluctuate significantly. Do not store the ointment in a car glove compartment during warm weather, as interior temperatures can exceed the recommended storage range within minutes on a sunny day. Do not freeze the ointment; freezing can damage the cream base and separate the active ingredient from the vehicle.

Always keep cold sore ointment out of the sight and reach of children. Even though accidental ingestion of small amounts is unlikely to cause serious harm, the tubes can look similar to other cosmetic products and should be kept securely. Do not share the tube with other people – each person should use their own supply to avoid transferring viruses, bacteria or allergens. After use, wipe the nozzle clean with a tissue and replace the cap firmly.

Check the expiry date on the carton and the tube before each use. The expiry date refers to the last day of the month shown. Once a tube has been opened, a shorter in-use shelf life applies – typically 3 months, but this varies by product. The in-use shelf life is shown as a small open-jar symbol with a number (for example, "3M") on the packaging. Do not dispose of medications via household waste or wastewater; return unused medicines to your pharmacy for safe disposal. This protects the environment and reduces the risk of accidental exposure for others.

What Does Cold Sore Ointment Contain?

The active ingredient varies by product: docosanol 10%, aciclovir 5% or penciclovir 1% are the three most commonly used antivirals. Inactive ingredients (excipients) typically include a cream base such as mineral oil, petrolatum, propylene glycol, cetostearyl alcohol, poloxamer 407, and purified water. Patches use a hydrocolloid matrix without added antivirals.

Knowing exactly what is in your cold sore ointment matters if you have known sensitivities to specific excipients or if you are unsure which active ingredient is best suited to your situation. Below is a breakdown of the ingredients typically found in the main categories of cold sore products. Always refer to the individual package leaflet of the product you are using for a complete and accurate list.

Active Ingredients

• Docosanol (10% w/w): A long-chain saturated aliphatic alcohol with the molecular formula C₂₂H₄₆O. Prevents fusion of the viral envelope with the human cell membrane, blocking virus entry. ATC code D06BB11. FDA-approved OTC in 2000.
• Aciclovir (5% w/w): A synthetic acyclic guanosine analogue with the molecular formula C₈H₁₁N₅O₃ and molecular weight 225.21 g/mol. Phosphorylated by viral thymidine kinase; inhibits viral DNA polymerase. ATC code D06BB03.
• Penciclovir (1% w/w): An acyclic guanine analogue structurally related to aciclovir, with a longer intracellular half-life (about 10 hours). Molecular formula C₁₀H₁₅N₅O₃. ATC code D06BB06.

Inactive Ingredients (Excipients)

• Petrolatum / white soft paraffin: An occlusive base that helps form a protective barrier over the skin and prevents moisture loss.
• Mineral oil / liquid paraffin: Used to give the ointment a smooth, spreadable texture.
• Propylene glycol: A humectant and solvent; enhances drug penetration into the skin. Occasional cause of contact dermatitis.
• Cetostearyl alcohol: An emulsifier that helps maintain the stability of the cream.
• Poloxamer 407: A non-ionic surfactant used in some aciclovir and docosanol formulations.
• Purified water: The solvent base of the cream.
• Sucrose distearate / sucrose stearate: Non-ionic emulsifiers in some aciclovir creams.
• Benzyl alcohol: A preservative found in some formulations.

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