Cold sores or fever blisters are common skin conditions wherein people develop small, liquid-filled blisters on and around their lips or other areas. These blisters are caused by herpes simplex virus type 1 (HSV-1) or herpes simplex virus type 2 (HSV-2). Usually, cold sores are contagious and can be controlled through treatment. However, certain foods can worsen symptoms in individuals. Here are some foods that are best avoided while managing cold sores. Peanuts Nuts are among the biggest triggers of cold sores as they contain a large amount of arginine. This chemical causes flare-ups and worsens cold sores in people with the condition. Among nuts, peanuts and hazelnuts contain the largest reserves of this chemical, and, therefore, they must not be eaten when dealing with cold sores. Additionally, peanut butter must be avoided entirely for two to three weeks, the normal lasting period for cold sores. Oranges Citrus fruits are another big no-no when it comes to foods to eat when one is coping with cold sores. Oranges and grapefruits are known for their citrus-filled refreshing flavor; therefore, one must avoid them at all costs. Such fruits contain an acidic element that will cause pain and a burning sensation when they get into contact with a cold sore blister.