Hayfever!!!

It's still summer - or at least it was sunny when I wrote this.  Knowing the British weather it could be raining now.  However rain doesn't always stop the effects of hayfever.

Pollen

Allergic rhinitis is an allergic inflammation of the nasal airways. It occurs when an allergen, such as pollen, dust or animal dander (particles of shed skin and hair) is inhaled by an individual with a sensitized immune system. In such individuals, the allergen in affected individuals is mistakenly identified as a threat and triggers the production of the antibody immunoglobulin E (IgE), which binds to mast cells and basophils containing histamine. When caused by pollens of any plants, it is called pollinosis, and, if specifically caused by grass pollens, it is known as hay fever. While symptoms resembling a cold or flu can be produced by an allergic reaction to pollen from plants and grasses it does not cause a fever.

IgE bound to mast cells are stimulated by allergens, causing the release of inflammatory mediators such as histamine (and other chemicals). This usually causes sneezing, itchy and watery eyes, swelling and inflammation of the nasal passages, and an increase in mucus production.

To reduce the symptoms of hayfever science has developed a number of medications to alleviate or prevent the symptoms.  A fantastic website (Compound Interest) goes into this in much more detail including the amazing infographic below.

Click to enlarge

Antihistamine drugs include those such as cetirizine and loratadine. They work by binding to the H1 receptors that histamine usually binds to, preventing it from inducing an inflammatory response to the allergens.  As you can see from the infographic above some drugs must be taken before symptoms appear for them to be effective.  Click here for a full screen image.

For more information visit:-
http://www.compoundchem.com/2014/06/20/hayfever/
http://en.wikipedia.org/wiki/Hayfever