Foods do not cause fever blisters; fever blisters are caused by the herpes simplex virus. However, acidic or spicy foods can exacerbate fever blister discomfort and should be avoided during a breakout in order to minimize symptoms, according to WebMD.
Cold sores have many triggers, but food is not one of them, notes Abreva, a leading manufacturer of a top cold sore remedy. To reduce outbreaks, Abreva suggests avoiding triggers, including fatigue, since it can cause the immune system to break down and make it easier for cold sores to break out. Staying calm and handling stress can also help, as stress is a trigger for cold sores. Staying warm and avoiding exposure to cold temperatures and winter winds can also be beneficial, since dry air can dry out the lips and make them more prone to cold sore outbreaks.
When out in the sun, protecting the skin with sunscreen and a wide-brimmed hat can help to limit damage to the skin that can bring on a cold sore. Avoiding the flu or colds can also be helpful, so getting rest and drinking fluids when a cold seems imminent can help to stave off the development of both illness and cold sores.