eli5 How does an antihistamine like Hydroxyzine lower anxiety?

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Hydroxyzine is approved to treat anxiety. What’s the mechanism that makes this work?

Can all first gen antihistamines do this?

In: Biology

3 Answers

Anonymous 0 Comments

Apparently (I say apparently as I just read up on it) Hydroxyzine has some antagonist affinity for serotonin, dopamine and adrenergic receptors. Meaning it can bind to these receptors and not allow their respective neurotransmitters to bind and perform their normal function.

Because these receptors are involved in anxiety response and other mood related functions, it can act as an anxiolytic. Though because its affinity (likeliness for binding to receptors) at these sites is quite weak, the effectiveness would in turn also be quite weak.

To my knowledge, first generation antihistamines don’t normally have such properties.

Anonymous 0 Comments

First generation antihistamines cross the blood-brain barrier very easily. We have histamine receptors in our brain, specifically in our hypothalamus. These histamine receptors in the hypothalamus have a major role in our sleep-wake cycle. When they’re inhibited, we feel drowsy.

Anti anxiety medication is mostly just about relaxing the body. If you’re having an anxiety/panic attack, anti anxiety medication calms down all that extra activity. I would imagine that all first generation antihistamines have a certain amount of anti anxiety benefit, but hydroxyzine is the most successful. The anti anxiety is just a byproduct of the drowsiness, but some medications do it better than others.

Anonymous 0 Comments

Man, this reminded me of the most unbearable rage-inducing itch I’ve ever had when I stopped taking hydroxyzine. It was so bad that I was literally starting to peel my own skin off from all the scratching! Couldn’t sleep, couldn’t work, couldn’t concentrate. The living was constant. I was starting to feel rage from it all, like I wanted to kill myself. Took me a bit to make the connection then read itching was one of the possible side effects!

Basically got back on it ASAP and weened myself off.

What s freaking nightmare!