After 80% of cold sore sufferers admitted they've cancelled dates due to outbreaks, experts explain why the nasty mouth sores occur - and how to deal with them so you're ready to pucker up on Valentine's Day.

By Lisa Salmon.

If there's one thing that will stop you puckering up on Valentine's Day, it's a nasty cold sore on your lip.

They may be small - and often barely noticeable to others - but to the sufferer they can seem huge, and very obvious.

Indeed, a survey by skincare company Skin Shop found that cold sores had ruined at least one Valentine's Day for 30% of respondents, while 80% had cancelled dates due to outbreaks, and 40% said they'd rather risk getting dumped than go out with such an affliction.

The reality is, however, that if sufferers were brave enough to go on their dates, their partners would probably sympathise, as the Herpes Viruses Association (HVA) estimate that by the age of 25, 60% of people will have become infected with the herpes simplex (HSV) type 1 virus that most commonly causes cold sores.

How do you catch them?

The virus is very much a kissing disease, passed on by mouth-to-mouth from someone who has a cold sore on their face.

"It's skin contact with friction, so you're more likely to catch a cold sore off somebody if it's a long kiss, rather than just a peck on the lips," says Nigel Scott of the HVA.

However, as the virus is fragile and dies very quickly when it's off the skin, it's only caught by direct skin contact. So there's no need to worry about sharing cups or towels with sufferers. It can also be killed by water, or getting too hot or cold.

Not all people infected with HSV will develop cold sores as a result, say experts. In fact, only around a quarter of carriers will ever experience symptoms.

"You can catch it and never get symptoms," says Scott. "Or there could be a trigger at any stage of your life and you get a cold sore."

What are the triggers?

Once you've caught HSV, it hides in nerve sheaths and can be reactivated by various situations, including tiredness, illness, stress, being run-down, menstruation, too much alcohol or the ultraviolet rays from sunbeds or sunlight.

Some people can have recurrent outbreaks as often as once a month.

Scott says: "If your mouth and lips get very sore if you do something like eat a very scratchy French loaf, if you get very run-down, or something upsets your immune system - any of these things can act as triggers.

"The immune system would normally keep this virus suppressed, but if it's really stretched with something else, sometimes it doesn't quite manage."

How does it feel?

There will be an itchy, tingly feeling on or near the lip when a cold sore is developing, and perhaps a feeling of pressure.

This is the time to treat the area, as at this stage it's possible to stop the cold sore developing, says Scott.

If left untreated, the itchy feeling develops into a small red patch, then a blister, which bursts and heals into the classic cold sore scab, normally lasting around a week.

Sores tend to appear where you've been kissed, although they can occasionally recur anywhere on the face. In general, the virus prefers the moist skin that lines the lips, mouth and nose.

Treatment The HVA says the best way to avoid cold sores is to look after yourself, and those who are prone to them should steer clear of any potential triggers.

GP Dr Phil Hammond, a patron of the HVA, warns that exposure to bright sunlight, which can trigger a cold sore outbreak, is a particular risk for skiers at this time of year, and advises them to use a good sun block.

"A few unlucky people seem to get frequent repeat outbreaks - sometimes triggered by stress, poor diet, lack of sleep or exposure to bright sunlight," he says. "A long-term course of antiviral tablets can deal with this."

Aciclovir, a medication used to treat a variety of viral infections including cold sores, shingles and chickenpox, is commonly prescribed to sufferers, and some aciclovir creams can be bought over the counter at pharmacies.

Other cold sore treatments include using a herbal cream made with lemon balm, or a liquorice balm, which can help reduce the severity and duration of outbreaks.

Medical nutritionist and former GP Dr Sarah Brewer says liquorice extracts stimulate immunity by increasing production of the antiviral substance 'interferon'.

"When applied to the lips, it suppresses the production of viral proteins needed to keep the herpes virus in its latent state, so they're less likely to cause an eruption," she says.

"When applied to a sore, it promotes more rapid destruction of infected cells."

Fight those cold sores The Herpes Viruses Association has these suggestions for sufferers...

:: Start treatment as soon the characteristic tingling starts.

:: Apply well-wrapped ice for 90 minutes to cool the area.

:: Use over-the-counter creams.

:: Apply cold, used teabags to the sore every hour.

:: Use tea tree oil or geranium oil to help speed healing.

:: Keep the sore moist so it doesn't crack with a dab of Vaseline.

:: See your doctor for antiviral tablets if you have recurrent outbreaks.