Hives (urticaria) are sudden breakouts of intense red often blotchy skin swelling. They can occur almost anywhere on the skin surface (including scalp) but occur most commonly on limbs and trunk.
They vary in size from mico dots to large discoid shape. The hive surface may be hot and itch intensely, and in some cases may burn and sting. Scratching may worsen the itch. The reactions last for a few minutes to a few weeks. Rarely, they last more than 6 weeks (chronic hives). It's said that acute urticaria affects 20% of the world population at least once in their lifetime.
Patients suffering from hives suffer through the day and night, losing sleep and are often frustrated and even depressed.
What Causes Hives?
The swellings in an acute episode usually come on within a few minutes and last for a few hours, only to completely resolve (disappear) within hours. So what happens during an episode? Disregarding the trigger(s), there are a series of events that occur within our immune system. The primary event is the release of an inflammatory (swelling) chemical called Histamine by our immune system. When an allergen (Eg dust mite protein) comes into contact with the immune system, it triggers a chain reaction within the immune cells (namely the mast cells), which results in the release of Histamine (Simplified explanation).
Histamine, in turn, causes the tiny blood vessels (capillaries) just under the skin to dilate that causes local skin cells to retain fluid (swelling/heat). Histamine also stimulates the skin nerve endings that cause intense itchiness. Scratching causes more tissue swelling and thus more itchiness.
Possible causes of hives:
- Foods Milk, Egg, Nuts, Seafood, Fruits, Spices
- Drugs Antibiotics, NSAID(painkillers), ACE inhibitors
- Viral Infections
- Insect Stings
- Allergens House Dust Mites, Cat/Dog/Rabbit Furs,
- Others Stress, Temperature change, Autoimmunune disease
- Idiopathic Unknown cause
What is Angioedema?
Angioedema is swelling of deeper tissues of skin - namely the subcutaneous and mucose membranes. It's easily seen where there is thick layers of subcutaneous tissue such as around eye socket (orbit) and lips. When an allergic reaction is severe it may involve the tongue and throat which may lead to breathing difficulty.
What test can I do?
First of all, seek out a doctor who treats allergic disease. Diagnosing urticaria involves a detailed medical history taking, blood tests of the immune system and the allergy tests where appropriate.
The doctor may ask the patient to keep a medical log on timing of urticaria in relation to food, allergy exposure and frequency of episodes.
In some cases, the allergy doctor may conduct a skin prick or a patch test of different allergens to determine sensitivity.
Is there treatment available?
Urticaria may spontaneously remit after a couple of weeks in some cases. Here, the doctor's main aim is to control symptoms such as itch and redness. He may recommend antihistamines and corticosteroids to keep histamine action to a minimum. In persistent urticaria, the doctor may run deeper blood analysis on the immune system to determine if the urticaria is part of a bigger autoimmune disease.
The use of biologic agents such as xolair (omalizumab) is gaining popularity in steroid-resistant urticaria. However, high drug cost remains a challenge for mainstream usage.
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