I think what you're referring to is commonly called 'wax' and it's essentially just highly refined thc extracted from weed. Idk about it keeping you high for "days" but it's pretty potent.
As for being worse, well, marijuana isn't actually that bad for you. I mean, yeah inhaling the smoke from ANY burning plant isn't really good for your lungs, but there haven't been any documented ill effects on human health from smoking weed, especially not if it takes less smoking to get just as stoned.
Still, the standard inebriant warning applies: you shouldn't operate heavy machinery or try to cook anything too complicated when you consume any form of marijuana, but I don't think there will be any lasting effects on a person's overall health.