Hives

Overview

Hives are more formally known as urticaria and cause red, patchy rashes on the surface of the skin. They form in a variety of patterns all over the body and can result from a food or medicine allergy. Hives that last less than six weeks are the result of an allergy while hives that result longer than six weeks are not.

In many occasions, chronic hives can occur even when there is no known cause. Angioedema is a related condition that occurs because of a fluid leakage in the blood vessels. Hives that last longer than a day tend to cause more serious complications. Hives can also develop as a result of exposure to poison oak and poison ivy.

Types

Hives are rashes that result from various types of reactions and allergies to food or medicines. Hives may be categories based on their symptoms, duration, and patterns.

• Acute urticaria: In some situations, an allergic reaction can produce hives immediately. These hives will last anywhere from hours to weeks. Most food allergies are categorized as acute urticaria. Many children and adults will experience these hives if they are allergic to peanuts, shellfish, or eggs.
• Chronic urticaria: These types of hives persist for longer than six weeks. Acute and chronic hives look almost identical, but chronic cases last much longer. With most people, chronic hives will clear in less than 20 years. It is sometimes impossible to identify what causes chronic urticaria.
• Drug-induced urticaria: These types of hives can cause heart failure. Certain drugs can cause these types of hives to develop.

Hives can occur as a reaction to heat, cold, water, scratches, sun, vibration, food, pressure, or certain chemicals. Some people may develop hives after exercising.

Symptoms

Hives are patchy rashes that are swollen and itchy. Although the patterns vary, most hives are welts with definable. Hives can change into different shapes, disappear, and reemerge on the skin over a period of days, hours, or minutes. When you touch the middle of a welt, it will turn white.

Causes/Risk Factors

In most situations, hives are the result of an allergic reaction to food or medicine. You may develop hives when you eat the foods that give you allergies, or you may develop hives when you are in close proximity of these foods. Certain medications cause hives. There is no identifiable cause for certain chronic hives.

Tests/Diagnosis

Most tests are visual. A doctor may conduct an allergy test to see what is causing you to develop an allergic reaction. Occasionally, the doctor will administer a blood test to confirm that a particular medicine or food caused the allergic reaction.

Treatment

In most situations, hives will disappear within a few hours or days. No treatment is necessary if the hives are not extensive. It is recommended that you avoid taking hot showers and that you avoid wearing clothes that will cause your skin to become further irritated.