What is Physical Urticaria?

Physical urticaria is a condition where exposure to a physical trigger causes hives. The term inducible urticaria also describes this type of hives. Examples of environmental triggers that cause hives include temperature changes, pressure, and water.^1-4

We do not know what causes people to have physical urticaria. Certain immune cells might be more sensitive to environmental conditions. This may cause these cells to release more histamine, leading to hives and other symptoms.^1-4

How many people have physical urticaria?

Physical hives are a type of chronic hive. This means that hives come and go for more than 6 weeks. Chronic hives affect about 1 percent of the population. About 20 to 30 percent of people with chronic hives have physical hives.¹

How is physical urticaria treated?

Treatment usually follows a stepwise approach. The first step is to avoid the physical triggers that cause hives. However, complete avoidance is not always possible.^2,3

Many types of physical hives can be treated with antihistamines. Doctors will start by giving you a non-drowsy antihistamine. If this does not control symptoms, they will increase your dose or suggest other drugs.^2,4

Some types of physical hives do not respond to antihistamines. In these cases, omalizumab (Xolair®) is usually the best option. However, the same therapy may not work for every person or all types of physical hives. This means treatment must be customized to each person, often by trial and error.^2,4

Types of physical urticaria

Different types of physical hives are defined by the environmental trigger. Many people with physical hives have a specific physical trigger as the only cause. Other people have a physical stimulus that worsens symptoms but is not the main cause. For others, multiple physical triggers cause hives.⁴

Cold urticaria

This type of physical hives is caused by skin contact with cold objects, liquids, and air. Hives usually develop within minutes of exposure.^5,6

Doctors diagnose cold hives using a cold stimulation test. They will apply a cold object to the skin and watch for a skin reaction. Treatment involves education about high-risk activities and avoiding cold triggers. It may also include antihistamines and other drugs.⁶

Dermographism

Dermographism is also called urticaria factitial or dermographic urticaria. This is the most common type of physical hives. It is often diagnosed while assessing other skin conditions, such as eczema.⁴

People with dermographism develop hives after stroking, scratching, or applying pressure. The hives usually appear within 6 to 7 minutes of the trigger and fade 15 to 30 minutes later. The hives are usually not itchy.⁷

Doctors diagnose dermographism by stroking the skin with a firm object. If the hives are not itchy, treatment involves avoiding triggers. Skin cream may be helpful if the skin appears dry. If hives are itchy, antihistamines are usually effective.⁴

Delayed-pressure urticaria

This type of hives happens several hours after applying pressure to an area of the skin. It is a delayed form of dermographism. Redness, swelling, burning, and pain are common symptoms.⁵

Some activities that often cause symptoms of delayed-pressure hives include:⁴

• Wearing tight clothing
• Sitting for a long time on a hard surface
• Extended periods of walking
• Carrying heavy bags of groceries
• Sleeping

Doctors diagnose delayed-pressure hives using your health history. In most cases, antihistamines alone cannot treat delayed-pressure hives. Doctors may combine them with other drugs, such as leukotriene modifiers and omalizumab.⁴

Cholinergic urticaria

This type of hives is caused by heating of the body, such as by exercise and strong emotions. This is different from other types of physical hives because the trigger is internal.⁸

Doctors use your healthy history and symptoms to diagnose cholinergic hives. They may also use challenge tests, such as a passive heat challenge or an exercise challenge.⁴

Exercise-induced anaphylaxis

In this type of hives, exercise is the only trigger. Typical symptoms include fatigue and hives that progress to wheezing and airway obstruction. Diagnosis is usually based on clinical history and sometimes an exercise challenge test.⁹

Local heat urticaria

This is a rare type of hives caused by direct skin contact with a warm object. Doctors diagnose it by applying a test tube of warm water on the arm for a few minutes.⁴

Aquagenic urticaria

This is a rare type of hives caused by direct skin contact with water. The water temperature does not matter, but the salt level sometimes affects symptoms. Doctors can diagnose aquagenic hives by watching for a reaction after applying body-temperature water on your body.⁴

Solar urticaria

This is a rare type of hives caused by direct exposure of uncovered skin to sunlight. Worse symptoms are linked to more intense sun exposure. Areas of skin that are more often exposed to sunlight are less sensitive.^4,5

Doctors use your health history to diagnose solar hives, sometimes along with phototesting. This procedure tests small areas of the skin with ultraviolet and visible light.^4,5

Vibratory urticaria

This is a rare type of hives caused by exposure of the skin to vibration. Common symptoms are itchiness, redness, and swelling. Some activities that trigger vibratory hives include:⁴

• Mowing the lawn
• Riding a motorcycle
• Horseback riding
• Mountain biking
• Working as a machinist or carpenter

Doctors can use your health history and a vibration challenge test to diagnose this type of hives.⁴