You’ve seen how aggressive your immune system acts towards pathogens, and without that aggressive stance we would die.

But sometimes the immune system can react to antigens which aren't dangerous.  

Allergies and Allergens

Allergic reactions are due to overreactions of the immune system. The immune system reacts to antigens which are not threatening, causing an allergic response.

Hay fever is an example of an allergic response.

Pollen particles enter the body, causing antibodies (Immunoglobulin IgE) to be produced by B cells.

These antibodies attach to mast cells and the pollen. Once attached they cause Mast cells to produce histamine and enzymes. Creating an allergic response.

Sore throat, puffy eyes, runny nose and breathing troubles are symptoms of hay fever.

Antihistamines are used to counter the effect of histamines, suppressing the symptoms. Cortisone actually suppresses the immune system, reducing the general response to pathogens.

Asthma is a respiratory allergy, but its not caused by histamines. In this way antihistamines wouldn’t be very effective against asthma.

Bronochodilating drugs that relax the muscles and open air ways are delivered through an inhaler, however they don’t affect the amount of mucus produced.

Watch the video to the right. You can clearly see the difference between the bronchioles of person suffering an asthma attack compared to a healthy individual.  

Anaphylactic shock is a life threatening over reaction of the immune system.

Circulating histamines and other chemicals cause bronchioles to constrict, blood vessels to dilate and loss of fluid to the tissues causing a decrease in blood pressure.

These reactions are caused by peanuts, stings and sea food.

People who suffer from allergic reactions will often carry their Epipens with them.

These Epipens contain Epinephrine (Adrenalin). This floods the system, causing blood vessels to constrict, increase blood pressure, relax smooth muscles, stimulate the heart and decrease swelling.