Overview
Cold sores are caused by herpes simplex virus, which remains dormant in nerve cells after the first infection and reactivates with stress, illness, sunlight, fatigue or hormonal change.
Genital herpes follows the same pattern. Both are very common, and the first episode is usually the most severe, with later recurrences shorter and milder.
When to seek urgent medical help
- • Cold sores with eczema spreading rapidly - urgent (eczema herpeticum)
- • Eye pain, redness or blurred vision with a cold sore - urgent
- • Weakened immune system, pregnancy near term, or an outbreak that is not healing
Symptoms and signs
- Tingling, itching or burning before any visible blister
- Clusters of small fluid-filled blisters on the lip or around the mouth
- Painful ulcers that crust over and heal within 7-10 days
- Swollen glands and feeling unwell during a first episode
- Painful genital blisters or ulcers with stinging on passing urine
- Recurrences in the same location each time
Management and treatment
Antivirals work by preventing viral replication, so they are most effective within 48 hours of symptoms starting - ideally at the tingling stage. Frequent recurrences can be managed with suppressive daily treatment.
Your ChatDoc doctor prescribes episodic or suppressive antiviral therapy and provides a supply you can keep at home to start immediately at the first symptom.
Prescription treatment options
Topical aciclovir cream
Applied five times daily from the first tingle for mild lip cold sores.
Oral aciclovir or valaciclovir
More effective episodic treatment for significant or frequent outbreaks.
Suppressive daily antiviral therapy
Daily dosing for six or more recurrences a year, reducing both outbreaks and transmission.
Trigger management
SPF lip balm, stress and sleep strategies and prompt treatment plans for known triggers.
Any prescription is issued only after a doctor has reviewed your case and considers the treatment safe and appropriate for you.
Your online Cold Sores & Herpes assessment
- 1
Tell us about your concern
Share symptoms, past treatments, medicines and relevant health information.
- 2
Upload clear photos
Upload photos of your concern where applicable.
- 3
Doctor reviews your case
Technology helps organise your answers, but every assessment and prescription decision is made by a doctor, who may message you if they need more information.
- 4
Get your personalised plan
A personalised prescription is issued if treatment is clinically appropriate.
Prognosis and outlook
Treated outbreaks typically heal in 4-6 days rather than 7-10. Cold sores do not scar when left alone to crust.
Recurrences usually become less frequent over the years, and suppressive therapy can reduce them by 70-80% while it is taken.
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This page is general medical information and does not replace a personal consultation. Always seek urgent care for severe or rapidly worsening symptoms. ChatDoc is not an emergency service. Call 999 (UK) or 112 (EU) for life-threatening emergencies or 111 for urgent non-emergency help. Do not wait for an online reply.