What They Are:
Antihistamines are a type of medicine used to treat nasal allergies and sometimes other types of allergies. Though they are not the only nasal allergies treatment choice, they are the most widely used one.How They Work:
The primary action of an antihistamine medicine, as the name suggests, is to block the action of a substance called histamine. Histamine occurs naturally in your body and is one of the main components involved in the immune response. It causes inflammation in the nasal passages and the airways and can lead to both nasal allergies symptoms, as well as asthma symptoms.An antihistamine medication keeps histamine from attaching to your cells and irritating them. And that prevents the immune response and inflammation.
The Effects:
The result of the histamine blocking is that you are less likely to have inflamed nasal passages. That means a lessening of such common nasal allergy symptoms as sneezing, runny nose, and itchy eyes or skin. Antihistamines can be used both for prevention and treatment of symptoms that have already begun.Examples:
Antihistamines can be grouped into 2 different categories:First generation antihistamines. These were the original allergy treatment. They are higly effective at relieving runny nose, sneezing, and other symptoms. Unfortunately, they have a significant side effect – they cause drowsiness. This sedating effect can carry over into the following day, even when just used at bedtime. Examples include:
- Chlortrimeton (chlorpheniramine)
- Benadryl (diphenhydramine)
- Dimetapp (brompheniramine)
Second generation antihistamines. The newer type of antihistamine is now the treatment of choice for most people who have nasal allergies. They are much less likely to have side effects of sedation and dry mouth and are just as effective. Most come in long-acting forms that need only be taken daily as well. Examples include:
Other Important Facts:
If you have nasal allergies along with allergic asthma, it's important that you keep them under control. When allergies are not under control, asthma control tends to slip as well. There are 2 methods for keeping both allergies and asthma under control – by avoiding the things that trigger your symptoms and by taking medication regularly. So, antihistamines are an important tool for both allergy and asthma control.In the past, first generation antihistamines were popular because they tended to be cheaper and more easily available since they are sold over the counter, without a doctor's prescription.
Unfortunately, as mentioned above, they also can have bothersome side effects. In addition, the older medicines can interact negatively with a number of other medicines, including sleeping pills, muscle relaxants and blood pressure medications. So, even though you can take them without a doctor's OK, you probably shouldn't, especially if you also have asthma.
It's a much better idea to have both your allergy and asthma care coordinated by either your family doctor or – even better – a doctor who specializes in this type of care, such as an allergist or pulmonologist. If you're not under a doctor's care, though, and you still want to access the safer and effective second-generation antihistamines, the good news is both Claritin and Zyrtec are now available over the counter too.
Antihistamines may be combined with decongestants at times, since the antihistamine alone is not that effective at controlling nasal stuffiness, or congestion. This may be the right choice for some people, though decongestants can have troublesome side effects of their own.Warnings:
Antihistamines are sometimes found in other types of combination medicines, such as pain relievers. If you are taking an antihistamine, be sure to read over the counter drug labels carefully, to make sure you are not "doubling up" on antihistamines. Alcohol should also not be mixed with this type of medicine, as it can increase the degree of drowsiness.In addition, if you have any of the following conditions, be sure to talk with your doctor before taking an antihistamine:
- Glaucoma
- Enlarged prostate
- Breathing problems of any kind, including asthma
- Heart problems and /or high blood pressure
- Thyroid disease
Sources:
American Academy of Allergy Asthma & Immunology. "Allergic Rhinitis." AAAAI. 13 Apr 2008.
American Academy of Allergy Asthma & ImmunologyAAAAI. "Tips to Remember: Rhinitis." 2007. AAAAI. 13 Apr 2008.
American Academy of Allergy Asthma & ImmunologyAAAAI. "Tips to Remember: Asthma and allergy medications." 2007. AAAAI. 13 Apr 2008.
Antihistamines: Understanding Your OTC Options." 10/06. Family Doctor.org. 13 Apr 2008.
