What are Hives?
Hives, also known as urticaria, is a kind of skin rash with red, raised bumps that appear in varying shapes and sizes. Hives usually cause itching, but may also burn or sting. They can appear on various parts of the body including the face, lips, tongue, throat, or even ears. They can last for several hours, or a day before fading. An estimated 20% of people will develop hives in their lifetime, but women are more likely to develop them than men. Hives also have the unique ability to change size rapidly and change locations on the body – they can appear and disappear from one area of the body to the next in a matter of hours.
Angioedema is similar to hives, but the swelling occurs beneath the skin instead of on the surface and characterised by deep swelling around the eyes and lips and sometimes of the genitals, hands, and feet. Angioedema generally lasts longer than hives, but the rarely lasts longer than 24 hours.
Causes of Hives
Although hives are common, their causes can be elusive. Most hives frequently occur following an infection or as a result of an allergic reaction to substances such as medication. Some hives can be a result of allergic reactions to insect bites or food. Allergic hives and angioedema form in response to histamine – blood plasma leaks out of small blood vessels causing the reddish appearance of hives. Hives can also form when there is direct physical stimulation of the skin by heat, cold and sunlight. Some patients are known to have hives due to extreme stress.
Types and Symptoms of Hives
Hives fall into two categories based on the amount of time they are present: acute urticaria which are ordinary hives that resolve after six to eight weeks and chronic urticaria that continues for after six to eight weeks. Here are some of the most common types of hives –
|Type of Hives||Symptom of Hives|
|Cholinergic Urticaria||A type of physical urticaria caused by sweating during physical activity or emotional stress. Hives produced are typically smaller and shorter-lasting.|
|Chronic Cold Urticaria||Caused by exposure of skin to extreme cold, damp and windy conditions. There’s a rapid onset of hives on face, neck or hands after the exposure to cold. This form of chronic urticaria can last up to five to six years and mostly affects young adults.|
|Dermatographic Urticaria||Appearance of weals or welts on the skin as a result of scratching or firm stroking of the skin. Skin becomes raised and inflamed when stroked, scratched and rubbed. The skin reaction usually becomes evident soon after the scratching, and disappears within 30 minutes. This is the most common form of chronic hives.|
|Food Allergy||The most common food allergies in adults causing hives are shellfish and nuts. For children, hives can be caused by allergies to eggs, shellfish, nuts, wheat and soy. Hives that appear are commonly found along arms, neck and face.|
|Medication Allergy||Drugs that have caused allergic reactions and the onset of hives include codeine, dextroamphetamine, aspirin, ibuprofen, penicillin, anticonvulsants, vaccines, and antidiabetic drugs. The hives caused usually appear as slightly reddish raised bumps on skin.|
|Solar Urticaria||Occurs on areas of skin exposed to sunlight and hives onset can be within minutes of exposure.|
|Water Urticaria||A rare form of urticaria that occurs upon contact with water. The appearance of hives can take place within 10 minutes from contact with water and can last for up to 2 hours.|
Treatments for Hives
The mainstay of treatment for hives is with oral antihistamines. Sometimes a combination of different antihistamines is used. Antihistamines are generally divided into sedating and non-sedating types.
You should continue to take the medications as prescribed by your doctor. For patients with chronic urticaria, we often require them to continue the medications for some time before stopping.
If there are known triggers, they should be avoided as much as possible. Certain medications, for example codeine-containing cough syrups, may exacerbate urticaria.
In very severe cases of urticaria, other medications are sometimes used – and these can include immunosuppressive therapy as well as a biologic therapy called omalizumab.