Hives (urticaria) is a type of rash or skin allergy that is ordinarily harmless. About 20% of us suffer from it during certain periods of our lives. It appears as red itchy patches on the skin if you have more serious stages when deeper skin layers are affected, face, hand or feet swelling can be observed. The rash consists of circular, raised welts on the skin that are usually itchy and occur in batches. Hives can vary in size, from as small as a few millimeters to as large as several centimeters in diameter. Hives also vary in the period they last. There can be acute and chronic hives. Acute hives last up to a month, the ones that are longer are considered to be chronic.
We know that hives are usually caused by an allergy. But non-allergic factors are also often. Hives can be caused by many different factors, including: medication, foods, and insect bites. With chronic urticaria, it is usually much more difficult to identify the offending allergen than it is with acute cases. Chronic hives can last 6 months or more. To make a diagnosis, a health care provider will see what the rash looks like, where it started, and ask about recent contacts. In about 80% of chronic cases of urticaria, the cause or offending allergen responsible for this condition is unknown.
Things That Cause Hives
Here we’ll have a deeper look at the factors that may trigger allergic reactions. These factors can be divided into two large groups: allergic causes and non-allergic causes.
Allergic causes include:
 o foods ( usually seafood, berries, nuts, eggs and chocolates)
o food additives (among them food preservatives and tartrazine)
o drugs (usually antibiotics, aspirin, medicines containing tartrazine, birth control pills, and medication for colds)
o contact with animals (dogs, cats) and plants
o insect bites
o worm infestation
o infections
o blood transfusions.
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