These side effects are known. www.drugs.com/sfx/loratadine-side-effects.html
Do you have any sensitivity to artificial flavors or sweeteners? There are some listed in the "professional" section under "inactive ingredients" of the drugs.com pages on this drug. I get heart reactions to these things.
This is normally a pretty good drug, but if you are sensitive to it you need to watch for this ingredient in other name brand antihistamines.