man looking into a mirror detecting if he has a cold sore

What are cold sores?

Cold sores may be tiny, but they can put a big dent in your confidence. Find out exactly what they are, what causes them and how you can prevent them

Written by Madeleine Bailey on January 22, 2019 Reviewed by Dr Gio Miletto on January 30, 2019

Why does it always happen?! You’ve got an important occasion coming up, and then you feel that tell-tale tingle on your lip. A cold sore is about to crop up and demand some attention – again.

Is there anything you can do to help tackle them – or even prevent them appearing in the first place? Get the low-down on cold sores with our guide.

What exactly are cold sores?

Cold sores are small, fluid-filled blisters that can appear at the corners of your mouth or on your lips, though they sometimes crop up elsewhere on your face.

The culprit is a contagious virus called herpes simplex virus. There are two types of this virus, HSV1 and HSV2 – but HSV1 is responsible for most cases.1  You’ll usually feel a tell-tale tingling, itching or burning before the blister appears, then bursts and crusts over into a scab.2

Are cold sores common?

Yes, and in fact, there’s a good chance you have the virus even if you’ve never had a cold sore. Seven in 10 people in Britain are infected by either HSV1 or HSV2 – but only one in four of those will notice cold sore symptoms. For the rest, symptoms may be so mild they’re not spotted.3,4

How do you catch cold sores?

First, you have to catch the herpes virus. This can happen by coming into direct contact with the infection – usually through a kiss from someone who has a cold sore, or someone who carries the virus but doesn't have symptoms. Cold sores are infectious from the moment the tingling starts until the sore has healed.5 You can also catch the virus by sharing lip balms or lipsticks with someone who has a cold sore, or even through oral sex with someone who has an outbreak of genital herpes.6 You can catch the virus at any age, but most people get it as children – usually through a simple kiss from a relative.7 When you first catch the infection, you may get no obvious symptoms, but some people, especially children under five years old, develop a sore throat, swollen gums with painful sores, and fever.8 Once it’s in your body, you have it for life, but it can lie inactive for years, until something triggers it.9

What triggers a cold sore?

Common cold sore triggers include:10
  • a flu-like illness
  • stress or emotional upset
  • tiredness
  • injury to the affected area, such as dental surgery
  • hormonal changes during your period
  • UV light from the sun or a sunbed

What to do if you have a cold sore

Cold sores usually clear up on their own in seven to 10 days, but ask your pharmacist for over-the-counter anti-viral creams, which can speed up healing time and ease discomfort. It’s crucial to use them at the first sign of a tingle. Paracetamol and ibuprofen can also help with pain and swelling.11

To help manage it:

  • always wash your hands after touching a cold sore and avoid touching broken skin
  • wash your hands thoroughly before touching your eyes – if the infection reaches your cornea, it could damage your sight12
  • be extra careful around babies – their immune systems are undeveloped and infection can lead to neonatal herpes, which is potentially serious13
  • never have oral sex when you have a cold sore – the same virus can also cause genital herpes14

If you’re looking for a herbal remedy, you could try:

  • l-lysine ointment – it may help shorten duration of cold sores, according to a 2005 study by Southern California University15
  • lemon balm (Melissa Officinalis) oil – a 2012 study by the University of Heidelberg, Germany reported that the herb had a direct effect on the herpes simplex virus to stop it replicating, so a lip balm with this oil in could be an effective preventative16

Tips to prevent cold sores

Some people get them two to three times a year, while others only ever get one. To reduce your risk of cold sores, get to know your triggers, while supporting your immune system with plenty of sleep and a healthy diet. Use sunblock of at least SPF15 if you find UV light triggers your cold sores.17

Do you need to see your GP about cold sores?

Not normally, but there are some exceptions. See your GP if:

  • you’re not sure if it’s a cold sore
  • your symptoms are severe, don’t clear up after 10 days, or keep coming back – your GP can prescribe antiviral tablets
  • the infection spreads to your eyes – especially if you notic pain, blurring, inflamed lids, red eyes
  • you’re pregnant
  • you have a compromised immune system, for instance if you’re taking certain cancer drugs or have had an organ transplant18
Shop Vitamins & Supplements Advice is for information only and should not replace medical care. Please check with your GP before trying any remedies.


1. Rhalou Allerhand. Netdoctor. Do I have a cold sore? 2. NHS. Cold sores 3. Oliver L et al. Seroprevalence of herpes simplex virus infections in a family medicine clinic 4. Herpes Viruses Association. Cold sores – questions and answers

5. As Source 2

6. Patient. Cold sores

7. As above

8. NHS Inform. Symptoms of cold sores 9. NHS Inform. Causes of cold sores

10. As above

11. NHS Inform. Treating cold sores 12. NHS Inform. About cold sores 13. NHS. Neonatal herpes

14. As Source 2

15. Singh BB, et al. Safety and effectiveness of an L-lysine, zinc and herbal-based product on the treatment of facial and circumoral herpes 16. Astani A, Reichling J, Schnitzler P. Melissa officinalis extract inhibits attachment of herpes simplex virus in vitro

17. As Source 2

18. As Source 2

Related Topics

Cold SoreConditions