Common allergies are known discomfort or reaction that manifest when the immune system comes in contact with a harmless substance, also known as allergen. Normally a person who is not allergic to a substance will not feel any reaction.

However the opposite happens if the person is allergic to a substance. That's because the immune system is triggered thereby mistakenly believing that this substance is harmful to your body. To protect the body, the immune system produces antibodies that cause certain cells release chemicals into the bloodstream. The chemical acts on the eyes, nose, throat, lungs, skin, or gastrointestinal tract and causes reactions; sneezing, runny nose, nasal congestion, itching, rash, nausea, vomiting, stomach aches, diarrhea and many others.

How common allergies develop in a person is still unknown. Some allergies are hereditary, family member can all have the same allergy for a certain type of food.

Common allergies are often caused by a direct intake with food substance. Any food form is a potential allergen to sensitive individuals. The most common are allergy towards cow's milk, eggs, chicken, shellfish and the like.

Another source of common allergies are airborne substances like pollens, dust, smoke, perfumes, and other chemicals. These substances may affect the respiratory tract, bringing on sneezing, coughing, and breathing impairment.

A person may also develop an allergic reaction towards inhaled spores or fungus particles. Mold spores trigger a reaction in the cell tissues that line the nasal passage. Because the substance is very small it can easily reach the lungs and bring about buildup of mucus, wheezing, and difficulty in breathing associated with asthma. Dust and animal hair (from cats and dogs) can also cause common allergies which lead to asthma attacks.

There are also man-made allergens that brings about all sorts of reactions. “Meat wrappers' asthma,” is a common form of allergy which results from inhaled poly-vinyl chloride fumes. This substance is found in packages used to wrap processed foods, When inhaled this can result in burning eyes, sore throat, wheezing and shortness of breath, upset stomach, and other complaints.

Another common allergy is a reaction from smog produced by motor vehicles. The smog is composed of hydrocarbons, oxides of nitrogen, and other chemicals activated by the energy from the sunlight. The smog can impair the normal function of the lungs, bringing about respiratory discomfort.

Medicines and drugs, like penicillin, or serums used in inoculations, can also cause allergic reactions. According to medical scientists chemicals in certain drugs combine with protein molecules in the patient's body can form an allergen, which can trigger a reaction from the body's immune system.

Another source of common allergies are insect stings by bees, fire ants, yellow jackets, wasps, or hornets, This can all cause serious allergic reactions. A single sting to a sensitive person may lead to a serious drop in blood pressure, shock and possibly death.

Antihistamine is the best cure for common allergies, an effective antihistamine is the best cure. This neutralizes the allergen, and provides relief from most symptoms.