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Cold Sore vs Impetigo: Getting the Right Prescription

Published on: June 03, 2026

Understanding the difference between cold sore vs impetigo prescription UK criteria is essential for effective treatment. Both conditions cause facial sores, but they require completely different medications — one is viral, the other bacterial. At Cured Pharmacy, our UK-registered clinical team can assess your symptoms through a free online consultation and prescribe the appropriate treatment within minutes.

Cold Sore vs Impetigo: Key Clinical Differences

Cold sores are caused by the herpes simplex virus (HSV-1), which remains dormant in nerve cells and reactivates periodically, typically around the lips and mouth [1]. They begin as tingling or burning sensations, followed by fluid-filled blisters that crust over within 7-10 days. Approximately 67% of the UK population under 50 carries HSV-1, though not everyone experiences visible outbreaks [1].

Impetigo, by contrast, is a highly contagious bacterial skin infection caused primarily by Staphylococcus aureus or Streptococcus pyogenes [2]. It presents as honey-coloured crusted lesions, often around the nose and mouth, and spreads rapidly through direct contact. Unlike cold sores, impetigo does not cause the characteristic tingling prodrome and typically affects children more frequently than adults [2].

The distinction matters clinically because cold sores require antiviral treatment (aciclovir), whilst impetigo requires topical or oral antibiotics (fusidic acid or flucloxacillin). Using the wrong medication will not resolve the infection and may delay appropriate treatment.

How to Identify Cold Sores: Visual and Symptom Recognition

Cold sores follow a predictable progression that helps differentiate them from bacterial infections. The prodromal stage begins 6-24 hours before visible lesions appear, characterised by localised tingling, itching, or burning at the site — typically the lip border [3]. This early warning sign is unique to viral reactivation and does not occur with impetigo.

Within 1-2 days, small fluid-filled vesicles cluster together on an erythematous base. These blisters rupture within 48 hours, forming shallow ulcers that weep clear fluid before crusting over with a yellowish scab. The entire cycle from tingling to complete healing takes 7-10 days without treatment, or 4-6 days with early aciclovir intervention [3].

Recurrent cold sores typically appear in the same location because the dormant virus resides in specific nerve ganglia. Common triggers include stress, UV exposure, illness, hormonal changes, and immune suppression. If you experience more than six outbreaks annually, suppressive antiviral therapy may be appropriate, subject to prescriber assessment.

When Cold Sores Require Urgent Medical Attention

Most cold sores resolve without complications, but certain presentations warrant immediate GP or emergency department review. Seek urgent care if lesions spread to the eyes (herpetic keratitis), which can cause permanent vision damage, or if you develop widespread facial lesions with fever, suggesting eczema herpeticum [3]. Immunocompromised patients should consult their specialist team at the first sign of reactivation, as HSV can cause severe systemic infection in this population.

How to Identify Impetigo: Bacterial Infection Characteristics

Impetigo presents quite differently from viral cold sores, beginning as small red spots that rapidly develop into blisters filled with cloudy or yellow fluid [2]. These blisters burst easily, leaving raw, weeping areas that dry to form the characteristic golden-brown or honey-coloured crusts. The lesions are typically painless but highly contagious.

There are two clinical forms: non-bullous impetigo (70% of cases) presents with the classic honey-crusted lesions around the nose and mouth, whilst bullous impetigo causes larger, fluid-filled blisters that remain intact longer before rupturing [2]. Bullous impetigo is more common in infants and young children, often affecting the trunk and nappy area as well as the face.

Unlike cold sores, impetigo spreads rapidly to other body areas through scratching and direct contact. Lesions may appear on hands, arms, and legs within days if left untreated. The infection is most contagious whilst sores are weeping and typically spreads within households and childcare settings. Patients remain infectious until 48 hours after starting appropriate antibiotic therapy [4].

Risk Factors for Impetigo Development

Impetigo most commonly affects children aged 2-5 years, particularly in warm, humid conditions where skin barrier function is compromised [2]. Risk factors include pre-existing skin conditions (eczema, chickenpox), minor skin trauma (insect bites, cuts), poor hygiene, crowded living conditions, and contact sports. Adults with diabetes or immunosuppression are also at increased risk. The bacteria typically colonise broken skin, though bullous impetigo can affect intact skin in susceptible individuals [4].

Aciclovir for Cold Sores: Prescription Treatment Options

Aciclovir is the gold-standard antiviral treatment for cold sores in the UK, available as both topical cream and oral tablets. The medication works by inhibiting viral DNA polymerase, preventing HSV-1 from replicating within infected cells [1]. Early treatment — ideally during the prodromal tingling phase — can reduce outbreak duration by 1-2 days and decrease lesion severity.

At Cured Pharmacy, we offer two aciclovir formulations: Numark Cold Sore Cream (5% aciclovir) from £4.49 for localised treatment, and oral Aciclovir tablets from £4.49 for more severe or frequent outbreaks. Topical aciclovir should be applied five times daily at the first sign of tingling, whilst oral aciclovir (typically 200mg five times daily for five days) is reserved for extensive lesions or immunocompromised patients [3].

Clinical trials demonstrate that aciclovir initiated within 48 hours of symptom onset reduces healing time from an average of 8.1 days to 5.7 days, with significantly reduced pain and viral shedding [3]. For patients experiencing six or more outbreaks annually, suppressive therapy (400mg twice daily) can reduce recurrence frequency by 70-80%, subject to prescriber approval following clinical assessment.

Antibiotic Treatment for Impetigo: Prescription Requirements

Impetigo requires antibiotic therapy, not antiviral medication, making accurate diagnosis essential before treatment begins. For localised impetigo affecting small areas (fewer than three lesions), topical fusidic acid cream applied three times daily for five days is typically first-line treatment in the UK [4]. More extensive infections require oral antibiotics, usually flucloxacillin or clarithromycin for penicillin-allergic patients.

NICE guidelines recommend oral antibiotics when impetigo is widespread, systemically unwell patients, or when topical treatment has failed after one week [4]. The standard course is flucloxacillin 500mg four times daily for seven days in adults, with dosing adjusted for children based on weight. Patients should see improvement within 48-72 hours, with complete resolution expected within one week.

Unlike cold sore treatments available through online pharmacy consultations, impetigo treatment — particularly oral antibiotics — typically requires GP assessment to exclude complications such as cellulitis or post-streptococcal glomerulonephritis. However, straightforward cases may be suitable for online prescriber review if high-quality photographs clearly show characteristic honey-crusted lesions without systemic symptoms.

Preventing Impetigo Spread in Households

Impetigo's high contagion risk demands strict hygiene measures during treatment. Patients should avoid sharing towels, flannels, bedding, and eating utensils until lesions have fully healed [4]. Children should be excluded from school or nursery until lesions are crusted and dry, or 48 hours after starting antibiotic therapy. Regular handwashing, keeping nails short to prevent scratching, and covering lesions with waterproof dressings help prevent transmission. Household contacts who develop symptoms should seek prompt medical assessment.

Getting the Right Cold Sore vs Impetigo Prescription Online

At Cured Pharmacy, our UK-registered prescribers can assess both cold sores and impetigo through our secure online consultation platform. The assessment takes under three minutes and includes detailed questions about symptom onset, appearance, location, previous outbreaks, and medical history. High-quality photographs of the affected area help our clinical team make accurate diagnostic decisions.

For cold sores, we can prescribe and dispense aciclovir treatments immediately following prescriber approval, with discreet next-day delivery across the UK. Our Numark Cold Sore Cream starts from £4.49, offering transparent upfront pricing before you complete your consultation. All medications are genuine UK-licensed products dispensed by our GPhC-registered pharmacy (9012511) under the supervision of Superintendent Pharmacist Tarun Kumar (GPhC 2233073).

If your consultation suggests impetigo rather than a cold sore, our prescriber will advise you on appropriate next steps, which may include GP assessment for antibiotic therapy or, in straightforward cases, online prescription where clinically appropriate. We never prescribe medications that are unsuitable for your presentation — patient safety always takes precedence over convenience. Our clinical team is available on (+44) 116 4646009 if you have questions about which service is right for your symptoms.

What to Expect During Your Online Consultation

Your consultation begins with a medical questionnaire covering current symptoms, previous outbreaks, medications, allergies, and relevant health conditions. You'll be asked to describe lesion appearance, location, and duration, with the option to upload photographs for prescriber review. Our clinical team reviews every consultation individually — there are no automated approvals. If aciclovir is appropriate for your cold sore, you'll receive prescription approval within hours, with medication dispatched the same day for next-day delivery in discreet, unmarked packaging.

Scientific References

1. James, C., Harfouche, M., Welton, N. J., Turner, K. M., Abu-Raddad, L. J., Gottlieb, S. L., & Looker, K. J. (2020). Herpes simplex virus: global infection prevalence and incidence estimate, 2016. Bulletin of the World Health Organization, 98(5), 315–329. https://doi.org/10.2471/BLT.19.237149 [accessed 13 August 2026]
2. Bowen, A. C., Mahé, A., Hay, R. J., Andrews, R. M., Steer, A. C., Kerr, S., Currie, B. J., & Carapetis, J. R. (2015). The Global Epidemiology of Impetigo: A Systematic Review of the Population Prevalence of Impetigo and Pyoderma. PLOS ONE, 10(8), e0136789. https://doi.org/10.1371/journal.pone.0136789 [accessed 13 August 2026]
3. Spruance, S. L., Rea, T. L., Thoming, C., Tucker, R., Saltzman, R., & Boon, R. (1997). Penciclovir cream for the treatment of herpes simplex labialis: a randomized, multicenter, double-blind, placebo-controlled trial. Journal of the American Medical Association, 277(17), 1374–1379. https://doi.org/10.1001/jama.1997.03540410052031 [accessed 13 August 2026]
4. National Institute for Health and Care Excellence. (2020). Impetigo: antimicrobial prescribing (NG153). NICE guideline. Retrieved from https://www.nice.org.uk/guidance/ng153 [accessed 13 August 2026]

Information on this page is for educational purposes only and is not medical advice. All prescription treatments require clinical assessment by a UK-registered prescriber. Always consult a qualified healthcare professional before starting any new medication.