Can someone explain the 'opiate itch' to me? Is it related to circulation?

[Engage]

Am I damaging myself (my cardiovascular) by taking pain killers for my back?
I am itching up something awful. Can't sleep and take a generic antihistamine to stop the itching.

Is this healthy?

But mainly, what is the biological cause of the 'opiate itch'?
Thanks.

 

[Toz]

Histamine release I believe.

 

[Engage]

Ah, thanks.

Reading here that:

High doses of morphine produced peripheral vasodilation and frequently significant hypotension.
These effects are thought to be due, in part, to the release of histamine.

Confusing.


I guess the next question is...does taking an anti-histamine dampen the painkilling ability of these drugs?

 

[alovesupreme]

no, in fact, it can actually potentiate the effects of same. doctors will often prescribe a first-generation antihistamine like hydroxyzine with a opioid painkiller because of the "dose sparing" effect.