Dr Rob Hicks replies: Despite their name, cold sores are not just triggered by cold weather and cold winds, they are also triggered by the UV rays in bright sunlight. Other common triggers include stress, infections and over-tiredness, so avoid these as best you can.
You need plenty of immunity-boosting vitamin C, iron and zinc which you can get from the recommended five daily portions of fruit and vegetables or by taking a vitamin and mineral supplement. Don't smoke and keep the amount of alcohol you drink to within the recommended daily amounts (that's no more than three to four units a day). Take time out each day to relax and unwind and use a lip balm and skin moisturiser that contain a UV sun block everyday to protect your skin.
When a cold sore is on the way most people feel a tingle in the place where it's about to appear. This is the time to use a cream containing the drug aciclovir or tea tree oil or the herb Melissa.