Well, constant exposure desensitizes you to a degree, I've smoked pipes since the early '70's but have always done so in moderation. After several days of daily smoking, there is a bit of smoke inhaled naturally whether you want to or not, and the celia in the lung want to expel that and so you cough. Constant smoking and inhaling coat the lung until that mechanism breaks down. I keep my lungs clean so once I start to get a little cough, I stop for a few days. I avoid the more heavily nicotine types like Kentucky, but unfortunately, some of the best flavored plants are higher in nicotine, so if you want the flavor, you will get some nicotine buzz which raises the BP and constricts the arteries.
Constant pipe smoking is hard on the lips, tongue and mouth until you get used to it. A doctor friend told me though that in his experience, any problems developed like a lesion, etc., are caught during dental exams long before they get serious and can be addressed. Then there are genetics: George Burns smoked cigars heavily until into the '90's and died of old age.
And of course, the biggest side effects are the friends you make, or lose as a result of your smoking, being looked at as if you are some freak when in public, and of course the damage to the pocket book, as once you find how enjoyable the pipe is and realize all the rest are rather inconsequential, you will undoubtedly buy lots of pipes and tobaccos anyway! After all, something is going to kill you eventually, so you might as well enjoy yourself! Chances are very good that a doctor, lawyer, automobile, processed food, taxation or regulations will kill you long before the pipe does.
