Hives are also known as urticaria, and they cause raised white or yellow, itchy wheals surrounded by an area of red inflammation. It is an allergic reaction by the skin, causing the body to release histamine into the effected tissues. The size of the wheal itself varies, with the larger ones sometimes joining together in places to form an irregular rash. They usually cause severe irritation and usually appear on the limbs and trunk, but can appear anywhere. Acute urticaria develops rapidly and usually lasts for just as few hours - it is characterized by a feverish, faint feeling and occasionally nausea. Chronic urticaria can persist for a long period of time.

Common triggers include drugs such as aspirin and penicillin, food additives, food sensitivity such as milk eggs, shellfish and nuts, environmental factors such as exposure to cold, heat or sunlight, stress and anxiety, and bites and stings.

All fruits and vegetables contain some amount of vitamin C. Foods that tend to be the highest sources of vitamin C include green peppers, citrus fruits and juices, strawberries, tomatoes, broccoli, turnip greens and other leafy greens, sweet and white potatoes, cantaloupe and spinach. Vitamin C helps promote a healthy immune system and releases antihistamines. Green tea is also reported to have an antihistamine effect.

Vitamin B12 has been reported to reduce the severity of acute hives as well as to reduce the frequency and severity of outbreaks in chronic cases. Vitamin B12 is found in animal foods, fortified foods, and some fermented foods. Some sources of B12 are eggs, meat, poultry, fish, dairy products, and foods made from soy. Salmon and low-fat milk are particularly good sources. If you suffer from food allergies, it's important to keep a detailed food diary. Note what you ate when you have hives breakouts, as it may be just a simple matter of eliminating a food or several foods from your diet in order to avoid suffering from hives.