I've never used it but the reasoning behind it on top of its sedating effect is probably to reduce the stress of a foreign feeling from hives or any other of the things an antihistamine is used for.
It would really depend what is your trigger, such as difficulty breathing. Also if you are using opiate pain killers.
If it was prescribed for you it is probably for good reason but not necessarily directly related to anxiety or panic. It could be just to reduce physical stress.
Unfortunately, moderators are unable to give medical advice. I will let the members share their experiences with you,and as always, consult your doctor and pharmacist before making any changes or mixing medications.
