Usually, substances such as pollen, animal dander, and dust are harmless. However, some of us have an immune system that believes these ordinary substances are a threat. In response, the body creates antibodies normally reserved for fighting true dangers, such as bacteria and viruses. Since the immune system incorrectly believes the allergen to be threat, it begins to create an immune response as if it were fighting off an illness. The immune system's response is what causes nearly all allergy symptoms.

There are a wide range of symptoms associated with allergies, and none of them are very pleasant. Allergy symptoms can range from very mild to life-threatening. If you suffer from allergies, you are not alone. Allergies, and other hypersensitivity reactions, currently affect approximately 30% of the population. The following is a list of some common allergy symptoms:

Nasal Symptoms are a common allergic reaction to a variety of allergens. Sometimes called Allergic rhinitis, or "hayfever", these symptoms afflict 20% of the US population and are often a result of airborne pollens, dander, dust or other allergens. Some common nasal allergy symptoms include:

Nasal Congestion (Stuffiness)
Sneezing
Runny nose
Itchy nose
Impaired Sense of Smell
Swollen Nasal Membrain
Sinus Headaches
Sore Throat (caused by nasal drip)

Skin Symptoms like hives, contact dermatitis, and exema (charachterized by inflamed, itchy or dry skin) are all relatively common forms of allergic reactions. Usually these types of skin symptoms occur when the skin comes into direct contact with an allergen, or it can be an immune response to eating food that you're allergic too. Some of these conditions can cause small, reddish bumps. They are caused by an inflammatory reaction, causing leakage from the capillaries of your skin.

Eye Symptoms, or Allergic conjunctivitis, is a common allergic reaction to many different types of allergens and can be caused by an allergen physically getting in the eyes, such as dust, or as a side-effect of a food allergy. It is caused when the conjunctiva (the membrane covering the white part of the eye) enflames due to allergy. One of the most common causes is hay fever. Symptoms consist of redness (mainly due to the swelling of small blood vessels), itching and increased tear production.

Ear pain, especially in children, is often a result of fluid building up pressure behind the eardrum. The middle ear is connected to the nasal passages by a short narrow tube, known as the Eustachian tube. The Eustachian tube drains fluids out of the middle ear, and helps keep the pressure of the ear equalized. Allergies can cause inflammation of the Eustachian tube, and cause secretions to build up, preventing the normal flow of fluid. This happens more often with children, because their Eustachian tube is shorter. These accumulating fluids can cause stuffiness, pain, hearing loss, and ear infections.

Headaches are not as common as other allergy symptoms, but some individuals will experience headaches, whether alone or in conjunction with other symptoms like nasal congestion.

Fatigue (tired feeling) can be caused by the immune response that you body is creating. Just like when you're sick, it takes a lot of energy for you body to get better. Even though you are not technically sick, your body thinks you are. That's what makes you feel so tired. In addition, some allergy medications can cause additional drowsiness.

Food Allergy Reactions happen when your body mistakes certain foods as harmful, and the reaction can become more severe every time the food allergen is encountered, but sometimes children can outgrow mild food allergies. Allergic reactions to food usually happen within a few minutes of eating the offending food, but it can sometimes take several hours to develop, which can make it hard to know which food is causing the allergy. It is very important to have it diagnosed if you suspect that you may have a food allergy, so that you can know for certain which foods to avoid. The first symptom of an allergic reaction to food is often itching and swelling in the mouth, tongue and throat. Some other common food allergy symptoms are:

skin reactions- hives, swelling, itching, eczema and redness
vomiting
diarrhea
coughing, wheezing or a runny nose
swelling of the lips
sore, red and itchy eyes

Severe Symptoms, known as Anaphylaxis, can be life-threatening. It consists of a series of reactions in which the entire body's response to the allergen comes on suddenly. It can begins with sudden itching of the eyes or face and within minutes can progress to more serious symptoms, including:

Swelling of the esophagus which can make breathing and swallowing difficult
Abdominal pain and cramping
Vomiting
Diarrhea or bowel irritation
Mental confusion and/or dizziness

How Can You Know if Your Symptoms are Allergies or a Cold?

Allergies, colds and flus all share many of the same symptoms like congestion (stuffy nose), runny nose, and sneezing. One way to tell is that colds do not usually last longer than 10 days. If your symptoms carry on longer than then, then you may be experiencing allergy symptoms. Another clue can be "itchiness". Allergies often cause an itchy sensation in either your eyes or nose. Your allergy doctor can help determine the cause of your symptoms and how to treat them. Here are some simple guidelines.

It's probably an allergy if:

You have no fever.
Mucus secretions are clear and runny.
Sneezes occur in a rapid, multiple sequence.
Your nose, ears, and throat feel itchy (especially the palate or roof of your mouth).
Symptoms last longer than the typical duration of a cold (which is usually 7 to 10 days).
Your symptoms get worse when you are in one environment, and get better when you are not in that environment.
Your nose, ears, and throat are not as itchy after you take an antihistamine.
You feel stuffy and congested. Take the Congestion Test to see if you need treatment.

It may be a cold or the flu if:

You have a fever.
Your symptoms occur all together - normal allergy symptoms tend to appear more gradually.
You have a sore throat.
Your symptoms last only 7 to 10 days.