By: Deborah Palmer

We are doing a series on “What’s in your medicine cabinet?”.  This week is all about allergy medications (antihistamines).

So before we can explain what an “anti”-histamine does we should explain the role of histamine.  Histamine is a substance that our body releases as part of its immune response with the goal of removing invaders. This is normally a good thing until your body starts sees seemingly harmless substances like pollen or peanuts as alien invaders, If you have allergies your body starts sends excessive histamine to the rescue when you really don’t need saving.

This excessive release of histamine leads to inflammation and typical allergy symptoms including watery eyes, nasal congestion and runny nose, sneezing, swelling, hives, itching.  The most worrisome is when histamine causes a severe, potentially deadly, reaction called anaphylaxis, in this case you develop swelling of the airway making it hard to breathing and inflammation of the blood vessels making them leaky causing a huge drop in blood pressure making it difficult to get blood your your vital organs.

So antihistamines do the opposite, they counteract histamine by competing for the sites where histamine wants to bind, if histamine cannot bind then the body cannot see the histamine, so your body doesn’t overreact and you decrease the allergy symptoms listed above.

Antihistamines are divided into two categories:

#1 First-generation Antihistamines

These include diphenhydramine (Benadryl), Chlorphenamine (Chlor-Trimeton), Promethazine. This generation of antihistamines are known for causing sedation as is crosses the blood-brain barrier.

#2 Second-generation antihistamines

These include Loratadine (Claritin), Desloratidine (Clarinex), Levocetirizine (Xyzal), Certirizine (Zyrtec) and Fexofenadine (Allegra).  The second-generation antihistamines are less sedating than the first-generation agents as they don’t cross the blood-brain barrier. These are preferred over the first-generation antihistamines because they have similar efficacy with less side effects.

What about Benadryl cream you ask?

Not a fan, if you’re looking for a topical agent to help bring down skin swelling, itch and pain (maybe help your poison ivy, check out our last blog post) topical steroids would be my first go to to calm the inflammatory skin reactions.  Topical Benadryl (though not sedating like the oral version) have been know to cause side effects such as sun sensitivity, rashes, hives

There are other allergy tips, tricks and treatments for specific allergy symptoms give Freedom Doctors a call and we can help come up with a plan for you.   If you develop any airways symptoms (itchy/swollen tongue, throat swelling, wheeze, shortness of breath) you may need a medication called epinephrine (aka epipen), so do not delay you need urgent evaluation ideally in an Emergency Room setting.

Other topics you’re interested in hearing about send us an email. Contact Us.