You don't have to inhale to ingest nicotine. It gets absorbed into the blood stream via the membranes of your mouth. One of the reasons why powdered snuff and chewing tobacco can be harder to kick than smokes.
Nicotine constricts blood vessels and raises BP.
Cigar smoke also contains carbon monoxide, and some other nasties like ammonia.
That being said, there's not really much risk from puffing on one occasionally. But many studies show that even one cigar a day can increase one's changes for mouth and throat cancers.