Antihistamines are medicines that block histamine receptors. Therefore, they prevent the histamine effects on our bodies. Histamine is a special chemical that is released from several of our cells, including our mast cells and basophils.
What are the First Generation Antihistamines?
Antihistamines have been on the market for nearly 50 years. Some first-generation antihistamines, such as Atarax (hydroxyzine), Benadryl (diphenhydramine), Silenor (doxepin) and Periactin (cyproheptadine) are still available for purchase. However, all of them cause some serious side effects that cannot be ignored. Because of the various side effects of first-generation antihistamines, second-generation antihistamines were introduced.
Which Antihistamines Sedate the Most?
First generation of antihistamines have a considerable amount of anticholinergic side effects. These side effects of first-generation antihistamines included sleepiness, urinary retention, dry mouth, and constipation. Because of these side effects, first-generation antihistamines are not recommended for a daily, routine use because of their sedative properties. Another intriguing fact about first-generation of antihistamines is that they greatly impair one's motor and mental functionality. That is why antihistamines of the first generation can impair one's ability to operate a vehicle or with heavy machinery. Moreover, a person from the United States that has taken a first-generation antihistamine and goes for a ride can be charged for driving under the influence if they cause a car accident.
What Other Side Effects are Caused by First Generation Antihistamines?
In addition to causing drowsiness and dry mouth, first generation antihistamines also increase a person's appetite and promote weight gain. Scientists claim that antihistamines promote weight gain because their chemical structure is similar to the chemical structure of several psychiatric drugs that were proven to cause weight gain.
Moreover, Periactin, an antihistamine of the first generation, has actually been given to cancer patients and children who were underweight. It was given to them because it promoted healthy appetite and weight gain.