The VA had husband on an antihistamine for anxiety. Due to his normal reactions to benadryl, I'm betting the way it works is through mild sedation.
As far as I am concerned, it's a nice once-in-a-while thing, but shouldn't be constant. For example - once we took Jett off all the expensive Rx allergy/asthma medications, and give him benadryl as needed only, he has FAR less problems with his allergies.
So - the two Janet mentioned are a possibility. I'm going to research the second one, with the "melt" factor it could be a possibility for Onyxx...
