It's safer then, say, tylenol, as far as that you can't OD on it...but the long-term effects of smoking anything can (though won't for all people) have a negative impact on your lungs (bronchitis, shortness of breath, increased risk of lung cancer)...you can eliminate that health risk though by eating it. Unless you've got a history of schizophrenia, I'm unaware of any other long-term health risks that have been verified by controlled medical studies.

There was a study that showed up recently though that it can increase the frequency of hallucinations in people with scizophrenia though.