Hives: Types and Causes

hives

Hives also known as Nettle rash and Urticaria, are red, swollen wheals on the skin that itch, burn or sting. It appears in varying sizes from size of a coin to size of a plate, appears suddenly and lasts from an hour to 24 hours. They show blanching that is when the red wheal is pressed in it’s centre it turns white.

What causes hives?

Hives occur as a result of an allergic reaction to substances present in the environment such as:-

  1. Food:- like peanuts, or shrimp.

  2. Medications

  3. Hay

  4. Pollen

  5. Temperature changes:- like exposure to extreme hot or extreme cold temperatures.

  6. Insects:- like bed bugs, mites, and beetles.

  7. Parasites:- giardia and pinworm are known to cause hives.

  8. Infection:- like in hepatitis and HIV.

  9. latex

What is the pathophysiology of hives?

Hives or urticaria are caused by an allergic reaction in the skin which is inflammatory in nature. There is release of histamine,prostaglandin D2,leucotrieneC4,bradykinin and other proinflammatory substances from the mast cells cause extravasation of fluid into the dermis layer of the skin that causes redness accompanied with swelling and itching(sometimes burning).

How long does it last?

Acute urticaria lasts from one hour to 24 hours sometimes to 6 weeks.

Chronic urticaria lasts more than 6 weeks.

What are the signs and symptoms of hives or urticaria?

The signs and symptoms of hives are as follows:-

  1. Sudden flaring up of skin for no reason.

  2. The wheals on skin are mostly red in color but in some cases they are also skin toned with clear edges.

  3. There is itching, burning and stinging in the wheals.

  4. They may be the size of a coin to the size of a plate, shape changes from time to time.

  5. They can disappear from one part and reappear on the other.

  6. When a red wheal is pressed in the centre it turns white this is known as “blanching”.

What are the various types of hives?

There are mostly 3 types of hives or urticaria seen:-

  • Acute urticaria:- lasts from 24 hours to 6 months disappear and reappear in between.

  • Chronic urticaria:- lasts more than 6 months can be distressing as it interferes with the sleep and causes itching, disappear and reappear with time.

  • Angioedema:- also known as giant hives is swelling in the deeper layers of the skin. Appears on the face on the lips and eyes, hands, feet and genital area. Swelling of the tongue or throat can be life threatening as it causes a blockage in breathing. In extreme cases of angioedema where immediate medical help is needed there is hoarseness of voice, difficulty in breathing, stomach cramps, and swelling of eyelids.

Management

Before seeking medical help some things can be done at home too such as:-

  1. Avoid foods that cause allergic reactions.

  2. Wear loose fitted cotton clothes.

  3. Take frequent baths to reduce the itching and swelling.

  4. Avoid sun exposure.

  5. Use aloe vera or calamine to reduce the itching on the skin.

  6. Don’t use harsh soaps on the skin.

  7. Use cold compress as exposure to heat mostly worsens the case.

 

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