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Signs of an Allergic Reaction

What are the signs of an allergic reaction or better put, what do we observe in a person who is having an allergic reaction?  Before discussing what the signs of an allergic reaction are, it may be helpful to understand what allergy is?  Allergy is a type of an immune response.  Your immune system is made up of many cells and proteins that circulate around our body to protect us from harmful substances like bacteria and viruses.  In addition, the immune system looks out for cells it does not recognize, like cancer cells and removes them.  The immune system is not perfect and that is why we get in infections, cancer and other diseases.  In the case of allergy, we not only react, but overreact to substances called allergens (a substance that triggers an allergic reaction) that would not normally be considered harmful like tree or grass pollen, animal dander, dust, medications or foods. 

It is not completely understood why certain people have reactions to allergens (pollen, animal dander, dust, medications and foods) and other do not, but most likely it is a combination of genetics, what we inherited from our mother and father, and our environment, what we come in contact with on a daily basis.  When the immune system overreacts (Allergy) to an allergen, it will respond in a way that makes you feel sick and how you feel are the signs of an allergic reaction. 

The signs of allergy can range from mild to severe and is dependent on how much allergen you come in contact with and how it enters the body.  The allergen can be inhaled, contact the skin, eaten or injected (medicine or insect stings).


In the case of inhaled allergens:

Sneeze, runny nose, stuffy nose, scratchy throat, drainage in the throat known as post nasal drip, itchy watery eyes, cough or wheeze, feeling tired or headaches.

A more intense reaction from inhaled allergens:

Swelling of the eyelids, redness around the eyes, mouth breathing and snoring due to severe nasal stuffiness, sore throat from post nasal drip, ear fullness or popping, chest tightness or shortness of breath and even itchy skin or rash.


In the case of contact to the skin:

Rashes such as hives (welts), eczema (itchy scaling rash), or swelling of lips, eyes, face, hands or feet.


In the case of eating a food or medicine, injection of a medicine or stinging insect:

All the signs of allergy noted above plus flushing or redness of the face, severe itching all over the body, nausea and vomiting, belly pain, diarrhea, difficulty breathing not only from asthma like symptoms (cough, chest tightness and wheeze) but from narrowing of the throat causing a choking feeling, low blood pressure causing dizziness and loss of consciousness and shock.  Anaphylaxis is the term used to describe the most severe form of an allergic reaction and includes many of these signs listed above.

If you experience a serious allergic reaction, seek medical care right away.


After the allergic reactions is over try to write down what you may have come in contact with, how long after the contact the reaction began and what treatment you received.  This information will help your physician determine what testing is needed to find out what you are allergic to.  Once the allergens are identified your physician can decide on a course of treatment that may include avoiding the allergen, taking medicine or actually receiving the allergen in the form of a shot or tablet (known as Immunotherapy) to teach your immune system to make a protective response versus the allergic response.  Allergy medications and Immunotherapy are not without risks so discuss the risk and benefits with your physician.

Finally, signs of an allergy can be caused by substances that are not allergens and the immune system is not involved.  In this case, the substance causing the reaction is an irritant.  For example tobacco smoke is not an allergen yet it causes many of the signs of allergy noted above including runny, stuffy nose, cough and eye tearing.  Allergy testing and Immunotherapy are not an option in this case but avoidance is.  It is important to distinguish between allergic and non-allergic reactions for the proper and effective treatment.