but, they both have been linked to heart problems and tachardia...

Maybe because they were orignially cogeners made from an insecticide used to kill helminths - a parasite of cattle.

People shouldn't supress histamines, because histamines have some sort of action to protect against cancer, hence people who have problems with high histamine levels in the blood, are much less likely to cause cancer...

The other alternative to anti histamines is to get essential fatty acids, from evening primrose oil, flax seed etc, or grass fed beef...