Chronic hives

Chronic hives may be spontaneous or inducible (physical). You can have both types at the same time. 

Spontaneous chronic urticaria is the diagnosis when the trigger for hives is not known.

Inducible or physical chronic urticaria is a reaction to a known external factor. This includes hives caused by the following:

• stroking your skin (dermographism) – this is the most common type of inducible/physical urticaria
• exposure to cold, cold water and cold objects (cold urticaria)
• sweating (cholinergic urticaria)
• direct contact with a substance such as stinging nettles, foods, preservatives, fragrances, plant and animal products, metals and rubber latex (contact urticaria) – this is different to dermatitis, which develops hours or days later
• pressure to your skin – this can be an immediate or delayed reaction (pressure/delayed pressure urticaria)
• exposure to sunlight or to artificial ultraviolet (UV) light (solar urticaria)
• direct contact of warmth to your skin (heat urticaria)
• exposing your skin to vibration, repetitive stretching or rubbing (vibratory urticaria)
• contact with water (aquagenic urticaria).

Some of these types are quite rare.

While external factors can be identified as triggers for inducible/physical hives, the cause of chronic spontaneous hives is often unknown, but it is likely to be an autoimmune reaction (where your immune system mistakenly attacks your own cells as if they were cells from a germ). 

Chronic spontaneous hives have also been associated with: 

• chronic underlying infection, such as Helicobacter pylori, bowel parasites
• chronic autoimmune diseases, such as systemic lupus erythematosus, thyroid disease, coeliac disease or vitiligo. 

Chronic hives are diagnosed if you have a long history (more than 6 weeks) of daily or regular hives. Your doctor will take a family history and do a physical examination. 

Inducible hives are often confirmed by inducing the reaction, such as scratching your skin in dermographism or applying an ice cube in suspected cold urticaria. 

Your doctor may ask for blood tests to rule out underlying conditions. 

Most people with chronic hives manage with appropriate doses of non-drowsy antihistamines such as cetirizine and loratadine. The doses for chronic hives are usually higher than the usually recommended doses. Although referred to as 'non-sedating', these medicines may still cause drowsiness especially at higher doses, so take care when driving or operating machinery.

If the cause is a specific food, food additive, shellfish, cosmetic or something else, avoiding those foods or substances will reduce the risk of hives coming back again. Also avoid anything that can make hives worse such as excessive heat, spicy foods or alcohol.

Steroid or antihistamine creams are not helpful and may cause skin changes or skin irritation.

People with severe symptoms interfering with quality of life may be referred to a clinical immunology/allergy specialist or dermatologist for assessment and consideration of additional medications.

Although chronic hives clear up in most cases, 15% of people continue to have symptoms at least twice weekly after 2 years.