Ever experience "invisible cotton" on your nose, or that annoying tick in your throat that you can feel working its way into a crescendo just as the sales clerk ask if you want to donate to a worthy cause? To understand how Antihistamines work, you must also understand why they work and what is going on inside your body.
Histamine is the chemical responsible for many of the allergic symptoms you experience like red itchy eyes, sneezing, and runny nose. It is an important part of the body's defense mechanism. When released in response to foreign organisms present in the nose like pollen, the histamine receptors are over stimulated which irritates the nose and eyes causing sneezing and itchy runny nose. Sometimes the body gets a little rambunctious and produces too much histamine which leads to an allergic reaction.

Antihistamines block the effects of histamine by "coating" receptors which prevents binding. This stops annoying symptoms like nasal congestion and itching. Antihistamine blocks the action of histamine at special sites (receptors) in the airways, nose, blood vessels and skin.
Antihistamines are used to relieve allergy symptoms like hay fever and hay-fever like symptoms all year round, certain allergic rashes such as nettle rash, itchy skin, insect bites and stings.
If you know you are prone to allergic reactions brought on by outside stimuli, it is important to take an Antihistamine prior to exposure. By the time your symptoms appear, the histamine has already began its attack on the cell receptors and your allergic reaction is in full bloom. So it is important to take an Antihistamine 2 to 5 hours prior to exposure to allergens. Or consider taking them on a regular basis.
As with any medication, there are side effects to be considered sleepiness is one. There are two types of antihistamines, those that are sedating, which list drowsiness as one of their main side effects, and the newer non-sedating ones, which rarely cause drowsiness.
Other less common side effects, include headache, difficulty in passing urine, dry mouth, blurred vision, and digestive tract problems such as feeling or being sick, constipation or diarrhea. Rarely, some antihistamines can also cause palpitations and abnormal heart rhythms, high blood pressure, allergic reactions (such as swelling, rash, and breathing difficulties), dizziness, confusion, depression, disturbed sleep, tremor, convulsions, blood and liver disorders, and over-excitement in children.

Learn more about this author, Valencia Whitlow.
Click here to send author comments or questions.

---

Add your voice

Know something about How antihistamines work?
We want to hear your view. Write now!