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What are Allergies?

Allergies are medically termed as hypersensitivity and increased reaction to the foreign substances. The substances that provoke allergies are known as allergens, which can come in contact through airways, skin, or eyes and be swallowed, inhaled, or injected. Allergies are very common in the general.
Most common allergens include; dust mites from house, mould, grass, tree pollens, pets hair from dogs and cats, fungal spores from damp areas etc.
Most common food allergens include; nuts and fruits, cow's milk, hens eggs, sea-foods, soya products, gluten etc.
Most common skin allergens include; rubber, latex, nickel, hair dyes, Wasp and bee stings, antibiotics such as penicillin, aspirin, and antihistamine meds etc.

What happens when a person gets allergy?

When exposed to allergens, the body fights with protein by forming antibodies known as immune response. When an individual comes in contact with allergens again the body’s immune response produces the same antibodies in huge amounts, which makes the release of chemicals such as histamines in the body and results in a complete allergic reaction.

Histamines are released from the mast cells present in nose, lungs, skin, or intestines, which may further lead to swelling and inflammation. Allergic reactions range from hay fever, asthma, and eczema. The severity of symptoms depends on the allergens that the person is exposed to.

When an allergic reaction becomes life threatening, it is termed anaphylaxis, which involves the entire body such as swelling of the mouth and throat, blockage of airways leading to difficulty in breathing, swallowing, and speaking, rashes and itching. This condition usually requires an emergency treatment.

Symptoms of allergies

  1. Runny nose and eyes.
  2. Wheezing, sneezing, and coughing.
  3. Itching of the eyes, ears, throat, lips, and roof of the mouth.
  4. Shortness of breath
  5. Skin rashes
  6. Lips and face swelling.
  7. Nausea and vomiting
  8. Abdominal cramps
  9. Diarrhea.
Diagnosis and treatment of allergies:

The diagnosis is usually made through a skin prick test by using multiple allergens to look for the exact cause of allergy. Allergies are best treated through prevention. The patients are advised to avoid the foods and activities that are prone to allergy detected by the tests. There are several drugs to cure the allergy symptoms but these drugs do not cure the tendency towards allergies.

Types of allergies:

Type I hypersensitivity: This is also known as immediate reaction, caused due to pollen, foods. Insect bites, and several drugs. Most of the allergies are of this type characterized by runny nose, runny eyes, and sneezing. Allergenic asthma is also of a type 1 allergy, occurs when the allergen is inhaled.
Type II hypersensitivity:  This type of allergic reaction is mostly seen after organ transplantation, which the body refuses to accept it as its own organ.
Type III hypersensitivity: This is also known as an Immune complex mediated reaction. This immune complex is the united form of an antigen and an antibody.
Type IV hypersensitivity: This is also known as Delayed reactions that are mediated by special immune cells called T-cell lymphocytes. These T cells take few hours to a few days to rise an allergic reaction such as contact dermatitis and poison ivy rashes.

Diagnosis of Allergy

The diagnosis is primarily based on the history and lab tests. The patient will be enquired about his family history of allergies. The first level relatives like parents and siblings suffering from certain allergies can be a significant finding. This is termed as atopy that often runs in the family. This is determined both by the genes and environment.

Skin Prick Test: This test is done to check for a potential allergens leading to allergic reaction. In this test, skin is pricked with a little amount of the suspected allergen and each of these sites is then marked with codes. If a person is allergic to certain allergens, the skin around the injected area becomes red, swollen, and itchy. This test can be done in all age groups including infants. This test cannot be performed in patients using anti-histamines and patients suffering from eczema.

Blood Test: Blood tests like RAST (Radio-Allergo Sorbent Tests) are performed to evaluate the amount of antibodies such as Immunoglobulin E and IgE. These are the antibodies produced in response to suspected allergens.

Patch Test: This test is used to find the allergen causing skin allergies, eczema, and contact dermatitis. In this test, a tiny amount of the suspected allergen is kept on metal disc. This disc is taped to the skin and left on for 48 hours. Upon removal, the skin reaction is noted. This test is usually performed by a dermatologist.

Mast Cell Tryptase Level Assessment: In this test, the serum level of β-tryptase is used to diagnose anaphylaxis and mast cell activity. Tryptase levels are peak at 45 to 60 minutes and may remain raised up to 24 hours.

CAST testing (cellular antigen stimulation test): This test is performed to check allergies to certain food additives and colors.