Are loratadine ones normally non drowsy?
Second-generation antihistamines (acrivastine, cetirizine, desloratadine, fexofenadine, levocetirizine, loratadine) don't cross the blood-brain barrier to the same extent as first-generation ones (chlorphenamine, cyclizine, promethazine, etc.), so they are much less likely to cause drowsiness.
Antihistamines cause drowsiness by blocking histamine receptors in a set of brain centres that form the ascending reticular activating system (ARAS), which is involved in maintaining wakefulness. In the brain, histamine is a neurotransmitter released from nerves arising from a centre in the hypothalamus (the brain region where all of the coordination of body functions goes on). When these receptors are blocked, the activity of nerves promoting wakefulness is reduced, so we become drowsy.* Consequently, antihistamines that reach the brain in appreciable quantities cause drowsiness, while those that can't get into the brain don't.
*Interesting fact (if you're interested in this kind of thing)... The ARAS receives stimulatory signals via activation of histamine receptors and inhibitory signals via activation of gamma-aminobutyric acid (GABA) receptors: the balance between histamine & GABA levels determines whether we are alert or sleepy. One of the actions of alcohol is to increase the activation of GABA receptors, so if you mix sedating antihistamines and alcohol you become very disoriented and sleepy and are likely to have accidents.