---
title: "Cold sores: Symptoms, Causes & NHS Treatment | HealthAnswers"
description: "Cold sores (herpes simplex on the lips) — triggers, treatment with aciclovir cream, when they are contagious, and difference from genital herpes."
url: https://healthanswers.co.uk/conditions/cold-sores/
robots: noindex
---

# Cold sores: Symptoms, Causes & NHS Treatment | HealthAnswers

Health A–Z

Cold sores (herpes simplex on the lips) — triggers, treatment with aciclovir cream, when they are contagious, and difference from genital herpes.

Written by HealthAnswers editorial team Medically reviewed by [HealthAnswers UK doctor review panel](https://healthanswers.co.uk/our-doctors/) Reviewed 3 July 2026

## Quick answer

What are cold sores? Cold sores are small blisters on or around the lips caused by herpes simplex virus (usually HSV-1) — tingling often precedes the blister. They heal in 7 to 10 days but the virus stays in the body and can recur. Highly contagious when blisters are present — avoid kissing and oral sex until healed. Antiviral cream started early shortens outbreaks; tablets for frequent recurrences.

## Who is this page for?

This page is for people in the UK who want a plain-English overview of Cold sores, including when to seek help and what NHS care usually involves. It explains general information, not what is wrong with you personally.

## Who should skip this page?

Skip this page if you need a diagnosis, a prescription, or emergency care. It cannot replace a GP, pharmacist, NHS 111 or 999. If you are in immediate danger, call 999; for urgent advice that is not life-threatening, call 111 in England, Scotland or Wales, or use your GP out-of-hours service in Northern Ireland.

On this page 8 sections

## Key facts about cold sores

- About 2 in 3 people in the UK carry HSV-1 — many never get cold sores.
- Tingling, burning, or itching (prodrome) before blisters is the best time to start antiviral cream.
- Cold sores are contagious until fully healed — virus spreads by direct contact.
- HSV-1 from cold sores can cause genital herpes via oral sex — not the same as "safe" because it's oral.
- Sun exposure, stress, illness, and periods can trigger recurrences.

## Cold sores — oral herpes simplex

**Cold sores** ( **herpes labialis** ) are **fluid-filled blisters** on or around the **lips and mouth**, caused by **herpes simplex virus (HSV)** — almost always **HSV-1**.

Roughly **two-thirds of UK adults** carry HSV-1; not all develop visible cold sores. Once infected, the virus **remains for life** in sensory nerves — **reactivating** as cold sores during triggers.

## Symptoms

### Recurrent cold sore (typical)

- Prodrome — tingling, burning, itching, tightness on lip — 12 to 36 hours before blister

- Blister cluster — painful, red base

- Weeping then crusting — heals 7 to 10 days

### Primary infection (first time — often childhood)

May cause:

- gums and mouth ulcers

- sore throat

- swollen neck glands

- fever — can mimic [glandular fever](https://healthanswers.co.uk/conditions/glandular-fever/)

Often more severe than recurrences.

## Triggers for recurrence

- UV light — sun, sunbeds — use SPF lip balm

- stress and fatigue

- colds and fever

- menstruation

- skin injury around lips

## Contagiousness

**Spread by direct contact:**

- kissing

- sharing lip balm, cups, towels

- oral sex — transmits to partner’s genitals ([genital herpes](https://healthanswers.co.uk/conditions/genital-herpes/))

**Most infectious** when blister is open; **avoid contact until fully healed**.

**Neonatal risk:** **never kiss a newborn** with active cold sore — rare **neonatal HSV** is devastating.

## Treatment

### Topical antivirals (pharmacy/GP)

**Aciclovir 5% cream** or **penciclovir cream:**

- apply at first tingle — 5 times daily for 5 days

- modest benefit if started early — shortens by ~1 day

### Oral antivirals (GP)

**Aciclovir, valaciclovir, famciclovir tablets** for:

- severe primary infection

- frequent recurrences (≥6/year) — suppressive daily dose

- ** immunocompromised** patients

See [aciclovir and antivirals](https://healthanswers.co.uk/treatments/aciclovir-and-antivirals/) guide.

### Self-care

- do not pick — spreads virus, risks bacterial infection

- cold compress for comfort

- paracetamol/ibuprofen

- keep lips moisturised after crusting phase

## Cold sores vs other lip problems

| Condition | Clues |
| --- | --- |
| Impetigo | Honey-crusted, bacterial, spreads fast |
| Angular cheilitis | Corners of mouth — fungal/bacterial |
| Aphthous ulcers | Inside mouth — not HSV typically on lips |
| Shingles | Unilateral dermatomal — see shingles |

## Eye involvement — emergency

**HSV keratitis** — infection of cornea:

- red painful eye , light sensitivity, blurred vision

**Same-day ophthalmology** — prevents scarring and vision loss.

## Prevention of recurrences

- sun protection on lips

- stress management

- suppressiv e oral antivirals if frequent

- avoid known triggers where possible

Cold sores are **common, benign for most**, but **contagious and recurrent** — early antiviral cream and trigger awareness reduce hassle and transmission.

## ! When to see a GP about cold sores

See a GP if cold sores are very frequent (6+ per year), spread widely on face, last over 2 weeks, occur with eye pain or blurred vision (urgent ophthalmology — HSV keratitis), or if you are immunosuppressed. Pharmacist can advise on aciclovir cream for typical lip cold sores. Seek urgent eye care if sore develops on eyelid with red painful eye.

## Common questions about cold sores

What causes cold sores? Herpes simplex virus type 1 (HSV-1) in most cases — stays dormant in nerve cells after first infection, reactivates causing blisters. HSV-2 can also affect the mouth. First infection may be severe with sore throat and swollen glands; recurrences are usually milder lip blisters only. How do you get rid of a cold sore fast? Start aciclovir or penciclovir cream at the tingling stage — 5 times daily for 5 days — may shorten outbreak by 1 to 2 days. Keep area clean, avoid picking, use SPF lip balm to prevent sun-triggered recurrences. Oral antiviral tablets work better for severe or frequent outbreaks — GP prescription. Are cold sores contagious? Yes — most contagious when blister fluid is present; virus also sheds at low levels before and after visible sores. Avoid kissing, sharing lip products, towels, and oral sex until fully healed. Do not kiss babies if you have an active cold sore — neonatal herpes is rare but serious. Can cold sores spread to genitals? Yes — HSV-1 from oral cold sores causes a growing proportion of genital herpes infections through oral sex. Condoms reduce but do not eliminate oral-genital transmission. See our genital herpes guide if genital symptoms develop. Why do I keep getting cold sores? Triggers include UV light (sun, sunbeds), stress, fatigue, illness, fever, hormonal changes, and skin trauma. Frequent recurrences — 6 or more yearly — may justify daily suppressive aciclovir from GP. Is there a vaccine for cold sores? No licensed vaccine currently. Antivirals manage symptoms; research continues.

## Sources

- [NHS — Cold sores](https://www.nhs.uk/conditions/cold-sores/)
- [BASHH — Herpes simplex](https://www.bashh.org/)