Urticaria is considered as one of the primary skin allergies. It is a condition that is characterized by the development of various types of extremely itchy and swollen pink or red bumps or patches on the skin. These patches may appear suddenly as a result of the body’s adverse reaction to certain allergens. They occur on the skin on any part of the body including the face, lips, tongue, throat or ears.  This type of rashes is also known as hives or welts.

The hives that appear on the skin vary in size and may appear and fade off in few minutes or can last for several days or for more than six weeks.

There are several different types of urticaria. Although the different types are all related, they do produce varying symptoms. Sometimes an individual may have more than one type of hives. There are four main types of urticaria (hives):

1. Acute urticaria
2. Chronic urticaria
3. Drug induced urticaria
4. Physical urticaria

1. Acute urticaria

Acute urticaria usually becomes evident a few minutes after contact with the allergen. Its onset is sudden and last only for few days. The reaction may last from a few minutes to several weeks, but usually less than six weeks.

This type of urticaria can occur with anaphylaxis reaction – a severe allergic response leading to difficulty in breathing and possible death.

Acute hives are usually caused by eating some foods that are allergic and in some cases the cause is usually not found. Common foods that cause rashes are shell-fish, milk, nuts, eggs, fish, soy, acid derivatives, and certain food dyes.

Other allergens antibiotics, bee or wasp stings or skin contact with certain fragrances also cause hives.

2. Chronic Urticaria

Chronic urticaria is characterized by hives that appear daily and usually last longer than six weeks. Visually, both acute and chronic forms of the disease are the same but the chronic form can persist for a long time. More severe cases can last up to 20 or more years.

It is difficult to find the cause of chronic hives. They can be caused by health problems like lupus or thyroid disease. They can also be caused by a bacteria or virus. Sometimes it can be an autoimmune disorder.

An identifiable cause for the problem is rarely found hence it is difficult to cure this hives. Their recurrence is also frequent.

3. Drug Induced Urticaria

This type of urticaria is caused by drugs which is a  very serious condition. It sometimes leads to hypotension and breathing problems . It  occurs within 24 hours after intake of the drug.

The symptoms include transient wheals with pale center and red borders. They show migratory pattern, changing in shape and location over several hours.

 Angioedema and serum sickness may occur associated with drug induced urticaria. Anaphylaxis reaction may occur with subsequent administration of the drug.

Drugs that may cause allergic reactions manifesting as urticaria include NSAIDS like Aspirin, Antibiotics like Penicillin, Sulfonamides, Anti-convulsants like Carbamazepine, Phenobarbital and Anti-diabetic drugs such as Suphonylurea.

4. Physical Urticaria

Physical urticaria does not occur spontaneously like other types of hives but it is rather induced by a physical stimulus. Stress, heat, cold, water, pressure and many other stimuli may cause physical urticaria.