Not exactly a perfectly harmless drug. It’s has strong anticholinergic side effects, especially in children and the elderly. You don’t want to gulp this stuff and drive, you may fall asleep behind the wheel. An older person may not be able to pee for a week and have instant Parkinson’s disease symptoms. There are much better antihistamines available. Read the warning label, they’re are much safer H1 blockers like Zyrtec. It’s far from a benign drug, especially in children where it can easily be lethal.
And yet in one of the most well-respected children's hospitals in the country, they routinely gave it to my 6 month old child to help him sleep.
It may be that Zyrtec or claratin will not be work the same as they are different generations of antihistamines.
For instance Claratin can be used for bone pain during treatment for leukemia/blood cancer treatments . When cells are rapidly multiplying, it causes bone pain due to the inflammation from histamines being produced. Only Claratin works tho. Not diphenhydramine etc.