I took 30 mg of loratidine by accident, do i need to go to the hospital?

Don't worry, No.: loratidine thankfully has a nice safety range. If you take too much, the worst that could happen is that you might feel sleepy. This is assuming it's plan Loratidine, not Loratidine D. (with pseudoephidrine, a decongestant)

WhatKindOf"Accident": Antihistamines are pretty benign unless you take s--tload of them. I expect you'll feel drowsy so if you need to stay awake,a stiff cup of coffee might help.If you are feeling dizzy or sick to your stomach, again you'll probably get through it OK,but if you are really worried then see a doctor, Just don't drive. All-in-all there will be no long-term effects except maybe a day or two of dry mouth.