Why Do Allergies Cause Hives?

Do allergies cause hives?

The answer is an obvious Yes. Read on to get a comprehensive account about hives and why they could be the undesirable side effects of an allergy attack.

Allergies Cause HivesAccording to the Academy of Allergy, Asthma and Immunology, allergies rank sixth in the list of total spending on chronic ailments. It affects about 20% of school going children and can lead to chronic conditions like childhood asthma. Skin reactions like contact dermatitis, urticaria are a common manifestation in any type of allergies. However, pet dander allergy, insect sting allergy and food allergies are the most significant triggers.

The skin is the first line of defense and very vulnerable as far as allergic reactions are concerned. Hives are essentially skin rashes that are exhibited as pale, inflamed, itchy red patches of skin. They are also known as Nettle rash or Urticaria. Most of the times, they are caused by allergies. However, there are instances when they are caused by non allergic triggers. Hives could be acute or chronic. The acute attacks lasting less than 6 weeks are the ones caused by allergies. The chronic variety which could go on beyond 6 weeks is seldom caused by allergies. They are mostly caused by other auto immune triggers.

Certain other causes of hives could be heat, pressure, friction, exercise and sunlight. Acute urticaria could also be caused by viral infections and by emotional upheavals caused by stress. Other chronic bacterial infections and metabolic disorders like impairment of thyroid function are also responsible for such skin reactions.

Hives often present themselves as clusters of swollen and red itchy bumps with a pre defined red base and border. These are known as Wheals. Wheals could be several inches in diameter.

Why do allergies cause Hives?

Allergies are essentially an auto immune response of the body. In individuals with a hypersensitive immune system, the body reacts to the otherwise harmless proteins and irritants in food or the environment respectively. The immune system treats these triggers as threats and produces an army of antibodies to put up a fight. These antibodies are known as Immunoglobulin E antibodies or IgE antibodies. These antibodies react and bind with the proteins. They stimulate the mast cells in the skin, gut and pharynx. The mast cells respond by producing the chemical, histamine. Histamine causes the adverse physical reactions experienced by the body in allergies. Histamine dilates blood vessels and causes inflammation. The walls of the blood vessels become more permeable and causes fluid leakage from the superficial blood vessels subcutaneously located underneath the skin. Histamine also irritates nerve endings and causes such reactions.

Symptoms of Hives

  • The symptoms appear immediately after coming in contact with the stimulant or within 72 hours.
  • Emergence of swollen skin lesions or welts. It usually affects the neck, throat, arms and legs. They are more common in females.
  • Intense itching along with burning and stinging sensation is common.
  • They have a tendency to disappear from one site and reappear in another and change their shape and size.
  • A related condition with hives is angioedema. This basically refers to a condition in which the different body parts get inflamed due to leakage from blood vessels deeper down. The face, mouth and lips get swollen.
  • In rare cases, hives along with angioedema, especially when triggered by an allergic reaction to insect venom or drugs can cause an emergency medical condition, namely, anaphylaxis. It is a condition which is characterized by a drop in blood pressure, breathlessness, wheezing, confusion and loss of consciousness.

Allergy Testing

  • It is important to see an allergist and get an allergy test done. Skin testing like that of the patch test, skin prick test and blood tests can be useful in detecting the allergen causing the reactions.
  • In case of food allergies, elimination diet, oral food challenges are administered to zero in on the proteins causing it.


Whatever may

cause hives

it is very important to treat them, as they can be a painful nuisance. Hives caused by allergies generally disappear soon after the trigger is removed and hardly last for more than 24 hours. Some of the ways hives can be treated are as follows:

  • Elimination of the allergen is the first step.
  • Antihistamines are the best medications known to counteract the excess histamine in the body. Benadryl, Claritin, Allegra are some of the over the counter antihistamines available.
  • Corticosteroids are required as part of a more aggressive form of treatment. However, they cannot be used for longer durations.
  • Atopical ointments can also help but are not suitable for prolonged use.
  • In case of an accompanying anaphylactic shock, a self administered dose of epinephrine needs to be administered.

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