Micrograph of urticaria. Dermal edema solid arrows in (A,B) and a sparse superficial predominantly perivascular and interstitial infiltrate of lymphocytes and eosinophils without signs of vasculitis (dashed arrow). Diagnosis is typically based on the appearance. The cause of chronic hives can rarely be determined. Patch testing may be useful to determine the<unk> . In some cases regular extensive<unk>  testing over a long period of time is requested in hopes of getting new insight. No evidence shows regular<unk>  testing results in identification of a problem or relief for people with chronic hives. Regular<unk>  testing for people with chronic hives is not recommended. Acute versus chronic * urticaria is defined as the presence of evanescent wheals which completely resolve within six weeks. Acute urticaria becomes evident a few minutes after the person has been exposed to an<unk> n. The outbreak may last several weeks, but usually the hives are gone in six weeks. Typically, the hives are a reaction to<unk> , but in about half the cases, the trigger is unknown. Common<unk> s may be the cause, as well as bee or wasp stings, or skin contact with certain fragrances. Acute viral infection is another common cause of acute urticaria (viral exanthem). Less common causes of hives include friction, pressure, temperature extremes, exercise, and sunlight. * urticaria (ordinary urticaria) is defined as the presence of evanescent wheals which persist for greater than six weeks. Some of the more severe chronic cases have lasted more than 20 years. A survey indicated chronic urticaria lasted a year or more in more than 50% of sufferers and 20 years or more in 20% of them. Acute and chronic hives are visually indistinguishable. Related conditions Angioedema Angioedema is similar to hives, but in angioedema, the swelling occurs in a lower layer of the dermis than in hives, as well as in the subcutis. This swelling can occur around the mouth, eyes, in the throat, in the abdomen, or in other locations. Hives and angioedema sometimes occur together in response to an<unk> n, and is a concern in severe cases, as angioedema of the throat can be fatal. Vibratory angioedema This very rare form of angioedema develops in response to contact with vibration. In vibratory angioedema, symptoms develop within two to five minutes after contact with a vibrating object and abate after about an hour. People with this disorder do not suffer from dermographism or pressure urticaria. Vibratory angioedema is diagnosed by holding a vibrating device such as a laboratory vortex machine against the forearm for four minutes. Speedy swelling of the whole forearm extending into the upper arm is also noted later. The principal treatment is avoidance of vibratory stimulants. Antihistamines have also been proven helpful.
symptom of Food allergy
symptom of Peanut allergy
symptom of Tularemia
symptom of Campylobacteriosis
symptom of Gastroenteritis
symptom of Gastritis
symptom of Laryngitis
symptom of Allergy