Allergy is defined as an abnormal reaction of the immune system to substances that are usually harmless to most people, and the allergens are called allergens. For chemicals to defend it, the most important of which is histamine, resulting in various and different symptoms in several areas of the body such as eyes, nose,throat, lungs, skin, gut, and symptoms between the simple annoying, severe and life-threatening.

Causes of allergies

The main cause of allergies is still uncertain, but it is clear that there is a relationship between allergies and genetics, as some types of allergies can sometimes be inherited through genes from parents to children, and genetic factors play a role in transmitting general susceptibility to allergies in individuals, but without specifying the type of allergy. The following is a statement of the most important types of allergens:
  Animals: such as dust mites, cockroaches, plus pet dander.  
  Medications: The most prominent examples are penicillin and sulfa drugs.                            Food: such as wheat, nuts, milk, eggs,and shellfish.                                                       
  Insect bites: the most important of these insects are bees, wasps, mosquitoes.                    Mold: Mold spores scattered in the air can cause allergies.                                                       Plants: Plant pollen, and the glues produced by some plants cause sensitivity in some individuals, and in fact pollen comes out of trees and herbs, while the glues are produced by ivy and poison oak.                                                                                                                  Other allergens: nickel metal and latex, from which some types of gloves are made.

Types of allergies

There are a wide range of examples of allergic reactions affecting the human body, the most important of which are:

Respiratory allergies

It includes several allergic problems, including:

Allergic : rhinitis is the most common type of respiratory allergy, and this allergy is clearly manifested at the end of adolescence or early twenties mostly, and in fact the symptoms of this type of allergy appear in the form of sneezing, congestion, and inflammation in Nasal passages, in addition to the eye sometimes affected, the patient feels the desire to scratch and shed tears, and it should be noted that there are two types of nasal allergies, namely seasonal allergies that manifest symptoms in a certain season of the year, and the constant allergy that the patient continues to suffer from throughout the year.

 Asthma: This type of allergy is an inflammation and narrowing of the airways, resulting in coughing, difficulty breathing,chest tightness, and a whistling sound from the chest during breathing, and some factors can stimulate the appearance of these symptoms, such as some respiratory diseases, exposure to cold and dry weather, irritants and allergens.

Skin allergies

 It includes several allergic problems, including:

Contact : dermatitis contact directly with allergens such as acids and bases found in detergents, toxic plants, some metals used in jewelry making, some topical medicines, rubber, perfumes, clothing Made of wool sometimes leads to an allergic reaction to the skin, resulting in inflammation of the skin ranging from redness to ulceration of the skin, this type of allergic reaction is characterized by the appearance of an itchy rash, and it should be noted that this type of allergic reaction is more common in adults.
 Eczema: Or atopic dermatitis, one of the most common types of skin infections, appears in the form of an itchy rash, accompanied by a severe dryness of the skin, and in fact the rash can be severe in nature, where swollen and red spots appear, with the possibility of leaching substances, while the chronic rash appears in the form of a thick skin with a dark color.

Food allergies

Any type of food can cause allergic reactions, but proteins found in cow's milk, egg whites, peanuts, wheat andsoy are the most common food allergies, while allergies to fruits, transistor, preservatives, and artificial colors are less common. In fact, allergic reaction often takes 5-30 minutes to eat, but it can sometimes be delayed, making it somewhat difficult to identify the main cause of allergies, and it should be noted that one in 25 children is confirmed to be food allergy to a food.

Pharmacological allergies

Here are the most important medications that may trigger an allergic reaction in the body after use:

- Some types of antibiotics, and the most common lybinic antibiotics cause allergic reactions.
- Aspirin and some other pain killers.
Muscle relaxants and medications used in local and complete anesthesia. 
- Dyes used for X-ray imaging ..

Other types

 Some of these are:

Arthrosis: Allergic conjunctivitis causes inflammation of the conjunctivitis as a result of exposure to some of the allergens found in hair washing and cosmetic preparations, smoke, and pool chlorine, and the conjunctivitis is known to be the part of the eye responsible for maintaining the moisture of the eyelid ball and eyelid.

Insect bite sensitivity: Exposure to bites of certain insects can lead to bloating and inflammation in the bite place, with the possibility of a rapid and severe reaction throughout the body known as anaphylactic reaction, namely the appearance of rashes, swollen airways, difficulty breathing and swallowing, increased pulse speed, and low blood pressure.

 Allergy Diagnosis

The doctor needs to diagnose the allergy to perform a physical examination of the patient, ask about the symptoms suffered, and find out what kind of new type of food has been recently taken, in addition to any substance that has touched or dealt with it recently, and may request some blood tests, in addition to a skin test to ascertain the nature of the substance causing the patient's allergies, It should be noted that the person who performs the skin test is the doctor who specializes in the diagnosis and treatment of allergies, this is done by placing a point of pure liquid form of the substance suspected of allergic reactions, then scratching the skin using a special tool, or by injecting a small amount of this substance into the skin, and after waiting approximately 15 minutes, the area is examined to notice any change, and in fact the result of the examination is a positive tumor in the case of redness. The place of examination, therefore the patient is allergic to this type of substance.

Allergy Treatment

Several drug groups are available for allergy treatment, in more than one pharmaceutical form, including cereals, syrups, sprays, drops, creams and injections, and the following is a statement of the most important of these groups:

Antihistamines: Antihistamines help oral antihistamines reduce runny nose, rashes, bloating, and reduce eye itching and tear, and it should be noted that some of these medications may cause drowsiness, including nasal sprays that help reduce sneezing, itching and runny nose, and sinus congestion. Eye drops containing antihistamines reduce redness, itching and bloating in the eyes.

Decongestants: Decongestants ensure quick and temporary treatment for nasal and sinuscongestion, available in the form of pills, syrups, drops and nasal sprays.

Corticosteroids: These drugs reduce allergic infections, and this group is available in the form of pills, syrups, inhalers, nasal sprays, eye drops and topical creams, In fact, corticosteroid-containing inhalers are usually used as a daily treatment for asthma patients, while oral forms are used to treat severe cases of allergic reactions because of their side effects.

Mast cell stabilizers: these drugs prevent the release of chemicals responsible for allergic reactions, and it should be noted that this group needs several days to begin to give the desired results. Leukotriene inhibitors help these oral drugs relieve respiratory allergy symptoms by inhibiting the action of the chemical Leukotriene inhibitors.

 Immunotherapy: This type of therapies are aimed at gradually training the immune system not to activate the response system when exposed to certain allergens, especially those that are difficult to avoid, such as plant pollen, dust mites, and mold, by gradually exposing the body to these substances, on precise dates, and in fact given in the form of a series of injections or pills under the tongue.

Epinephrine injections: Epinephrine shots are used in emergency cases to treat serious allergic shocks, and in fact individuals are advised to carry a self-injection device for epinephrine if there is severe food allergy or insect bites.