When you feel that itch coming on, your nose starts running, or you start sneezing, it may be the result of histamine. Histamine is one of the chemicals released when your body's immune system fights off the allergens it perceives as invaders' to your body. The histamine bonds to receptor cells in your nose and throat. Once the bond happens, your nose and throat will swell and the mucus will run, your sinus and nasal tissues will become inflamed, your nasal passages congested your nose runny, your eyes or skin itchy and more.

The problem is not that the allergens come into your body, that's normal. The problem is that some (many) people's bodies react to the protein in allergens as if they were a germ or a virus attacking the body. When the body perceives a threat, it releases chemicals to fight it off. This is a good thing when a virus or bacteria are in your body. It feels similar, but is an undeserved reaction when the body attacks "safe" substances.

Thus the purpose of antihistamines is to block the histamine bonds from forming. They do this by putting a layer over the cells so the histamine cannot join to it. In essence, they bond to the cells themselves preventing the other cells from bonding. If the antihistamine can prevent the bond, it can prevent symptoms. The newer antihistamines have much fewer side effects than older ones which caused sleepiness which made them dangerous for people who needed to pay attention. The newer ones cause little to no problem with this. They are much safer medications than those that used to make us sleepy all the time, making us choose between sleepiness without symptoms or symptoms without sleepiness.

If you know you will be exposed to allergens, taking an antihistamine about an hour or two before hand can prevent any symptoms because the receptor cells will not recognize the allergens, and they will not be able to make the bond that causes the symptoms. If you wait to take your antihistamine until after you have symptoms, your allergy symptoms will already be full-blown. Once the body's immune cells release histamine, it goes to work quickly and effectively. This is why, if you have allergies all the time, you should take your antihistamine on a consistent basis. Most prescription anti-histamines are given in pill form in a daily dose.

If you have chronic allergies, another medical problem, rashes or your allergy symptoms are new, you should see your doctor before taking anything. S/he can review your history and your symptoms and decide what would be the best course of medications for you. Asthma attacks and anaphylactic shock can be deadly, and your doctor can show you what to do to prevent problems or treat them. Don't forget that other symptoms, such as rashes or hives can also be a symptom of allergies

Learn more about this author, Angela S. Young.
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