How Do Antihistamine Medications Work – The Facts Behind This Powerful Allergy Treatment

Antihistamines have been used to help allergy sufferers for years. Most people don’t really understand Antihistamines or how they work. First it’s important to take a closer look at allergies and exactly what effect they have on the body.

Allergies are the result of your body having a bad reaction to an outside substance. These substances are typical allergens, such as pollen, dog or cat dander, dust, or a certain type of food. You’re body reacts by attacking them like they would any type of germ. This is done my releasing a substance called histamine. The byproduct of histamine is typical allergy symptoms like sneezing, watery eyes, rashes or hives.

Antihistamines work by fighting the histamine that’s produced by the body. In essence it protects the body from itself! More specifically it builds a protective wall around the cells of the effective area. Once the cells are protected, there’s nowhere for the histamine to take hold.

Like most medication, antihistamines historically has some negative side effects, the most notable being drowsiness. In the past many people would choose to deal with their allergy symptoms other then taking medication. What’s the point if you’re so tired you can’t complete your day to day tasks?

The good news is recently newer antihistamines have become available that fights histamine without causing drowsiness. Of these Claritin and Allegra are the 2 most popular. In the beginning they were only available by prescription, however that has recently changed. Now they’re both available over-the-counter. They have been a proven treatment for all types of allergies, with minimal side effects.

Antihistamines For Dogs – Selection is the Key

Antihistamines for dogs are sometimes an effective treatment for itchy skin caused by allergies and other conditions. Its use is usually part of a comprehensive approach to allergy control that may include other canine medications, the identification and avoidance of inhalant allergens, and other treatments.

Many family veterinarians and veterinary dermatologists now prescribe dog antihistamine only in conjunction with an omega fatty acid supplement, specifically with omega3 fatty acids.

While studies show that omega6 fatty acids are also important, they are found in sufficient amounts in daily diet. By adding omega3 fatty acids only, these two polyunsaturated fatty acids can be in a good working balance enabling them to be effective. Together, these fatty acids are known as “essential fatty acids,” or EFA’s.

Research clearly shows a marked improvement in antihistamine use success rates when used with omega3 fatty acids in an omega fatty acid supplement, such as 3V capsules. 3V Caps for dogs are actually fish oil capsules that include several vitamins (A, D and E) that support absorption of EFA’s into the body.

It is very convenient when a family vet can get a dog antihistamine to work. Antihistamines for dogs are inexpensive and they are a relatively safe medication. This is why it is often one of the first things a family vet will try.

Unfortunately, success rates using dog antihistamines alone are low, maybe 10 to 20%, but reinforced with essential fatty acids supplements success rates raise to 25 to 40%. Clearly, antihistamines drugs do not work for all dogs as well as they do in humans. But when the option is available, a good attempt should be made.

Obviously, dogs do respond differently to individual antihistamines drugs, so it may be necessary to try several different dog antihistamines before one is found that will be the most effective and with the least side effect (sleepiness).

Incidentally, note that some pharmacies are able to change the flavor or form of medications in order to make it more appealing to your pet, should administration be a problem.

How Antihistamines Work

For millions of us allergy sufferers, antihistamines ease the annoying discomfort accompanying allergic reactions. Being an allergy sufferer myself, through the decades I have taken both over-the-counter and prescription antihistamines, some of which have been discontinued. Allergic reaction symptoms include nasal congestion, sneezing, coughing, headache, and itching indicating sensitization to certain allergens such as pollen, mold, dust, or insect venom. Repeated exposure results in allergic reactions due to antigen-antibody interactions.

First, antigens come into contact with lung, gastrointestinal tract, and/or skin tissue, and enter into the bloodstream. Next, mast cells and white blood cells misidentify these as invaders and inappropriately respond by releasing histamines causing tissue injury. The severity of the allergic reaction is directly proportional to the amount of histamine released.

Histamines dilate small blood vessels and capillaries, but contract smooth muscles. Responses include decreased blood pressure, increased heart rate, difficulty breathing, constipation or diarrhea, heartburn and nausea, and proteins and fluids leaking from capillaries. Nasal mucous membrane capillaries leaking, result in nasal congestion. Skin capillaries leaking produce hives and swelling resulting in pain and itching.

Thankfully all antihistamines block most of histamines effects by competing at histamine receptor sites thereby preventing them from producing an effect on the tissues. Antihistamine drugs prevent, but can’t reverse, histamine responses. Some of the general uses of antihistamines include relief from nausea and vomiting, relief from motion sickness, and relief from coughs. Usually antihistamines are administered orally since they are well absorbed in the intestinal tract, or topically, although a few can be given intravenously. To maintain a therapeutic dose, these medicines are given two to four times per day because the liver rapidly metabolizes them.

First generation antihistamines, which can be used interchangeably, include chloropheniramine (Chlortrimeton®), diphenhydramine (Benadryl®), and promethazine (Phenergan®). Some of the side effects include nose and mouth dryness, and drowsiness. Some antihistamines are also used as local anesthetics because they depress sensor nerve activity. When taking these antihistamines, it is advisable to not drive or perform hazardous tasks, and not to use alcohol or other drugs.

Second generation antihistamines include cetirizine (Zyrtec®), and Loratidine (Claritin®), and third generation antihistamines include fexofenadine (Allegra®), claim to be more selective for histamine receptors and cause less drying or sedating. However, these are contraindicated in patients with hepatic dysfunction, and when taking certain antifungal, antibiotic, and serotonin release inhibitors due to unfortunate deaths. My personal experience with these antihistamines is I did not find the relief I needed.

Because of the sedative effect, antihistamines are used in sleep aids like Nytol®, or Tylenol PM®. Because of the drying effect, antihistamines are found in over

Claritin Antihistamine

Hay fever is one of the most common forms of allergies. It affects millions of people every summer. People who suffer from these seasonal allergies are generally allergic to pollen. Symptoms usually begin to appear in the early spring when the leaves start to appear on the trees and it can last through fall. Sometimes people will mistake the symptoms for the common cold, however cold symptoms usually last a week or 2, while allergy symptoms won’t go away.

There are many medications available to treat seasonal allergies. Of these many treatments, Claritin is the most popular. Since there is no cure for allergies, Claritin works by treating the symptoms. It’s an antihistamine which means blocks histamine. This may see obvious, but histamine is the chemical that causes nasal congestion, sneezing, runny nose and other allergy symptoms. Therefore by blocking histamine, you can control your allergies.

Side effects

Like any medicine Claritin has a few side effects that you should be aware of. People usually experience higher blood pressure, increased blood sugar levels and an elevated heart rate. These can be some of the most dangerous side effects, so if you experience any of them, make sure you consult your doctor as soon as possible.

The options are limitless

Most people take Claritin in pill form; however Claritin eye allergy relief drops are also available. These are epically helpful if your eye allergies are especially bad. While they only work on your eye allergy symptoms, the benefit of using eye drops is that they work right away. This is because it’s applied directly to the source of the affected area.


Remember, Claritin isn’t only for seasonal allergies. It’s an effective treatment for any type of airborne allergies. For example it can also be effective for people who are allergic to dog or cat dander.

If you’re a seasonal allergy sufferer, relief is available. Claritin is a safe antihistamine that has helped people who suffer from allergies find relief. It has been used by kids and adults alike.