Normally, when our body is exposed to an allergen to which it is sensitive, such as: pollen, animal dander or dust, among others, our immune system misinterprets that substance as a threat and triggers a response to fight it. This happens when proteins from an allergen bind to immunoglobulin E (IgE) antibodies on the surface of mast cells, causing the cell to release histamine. A substance that binds to histamine receptors, triggering reactions like a runny nose, watery eyes, and other classic allergy symptoms.
For their part, antihistamine medications, which are responsible for relieving allergy symptoms, bind to histamine receptors on cells throughout the body, preventing them from triggering immune system responses. That way, they can help control allergy symptoms. But, what side effects can they produce?
In this sense, both first and second generation antihistamines perform this function by specifically blocking the histamine H1 receptor since, although there are other types of histamine receptors, H1 is the most important for allergic reactions. However, you have to know how to differentiate one from the other, since the side effects they produce can be different.
First generation antihistamines
These were some of the first antihistamines to be developed. They work on the part of the brain that controls nausea and vomiting, which means they can also prevent motion sickness. The most common side effect of first-generation antihistamines is feeling sleepy.. For this reason, they are sometimes used to help people who have problems with insomnia.
Brompheniramine
Dimenhydrinate.
Diphenhydramine.
Doxylamine.
Second generation antihistamines
These medicines are more current than the previous ones and many treat allergy symptoms without causing drowsiness.
Loratadine.
Cetirizine.
Fexofenadina.
Side effects of antihistamines
Drowsiness.
Dizziness.
Dry mouth, nose or throat.
Increased appetite and weight.
Stomachache.
Thickening of the mucus.
Changes in vision.
Feeling nervous, excited or irritable.
Precautions to take when taking antihistamines
Before taking an antihistamine, it is best to inform our doctor about all the medical conditions that we have, especially if we suffer from:
Also, as an added precaution, doctors recommend not driving or engaging in activities that require alertness until we know how the antihistamine we are taking affects us.
Lastly, we may need to avoid intake of grapefruit while we take antihistamines, since it has been shown that it can interact with up to 85 different medications and, in some cases, generate serious adverse effects.