Don't know anything about the med, but how bad is your blood pressure? There are non-medication ways to control blood pressure that can be tried if you prefer that approach assuming this isn't a life-threatening level, and doctors seldom are aware of these methods. I don't know your health history, so obviously this is something you have to work out knowing how serious the problem is, but again, through dietary changes, exercise, meditation, and some very effective herbs a non-life-threatening case can be successfully treated without medication. If it doesn't work for you the medication won't go anywhere, you can still try it out. My own view is, when you need medication you need it, but drugs are prescribed very often when there's no need, it's just the easiest thing for a doctor to do -- non-medication treatment is more complicated and time consuming. Again, I'm not suggesting anything specific, just suggesting an alternative avenue if you aren't in urgent need of medication and have concerns about it.
Since you will be starting a new medication I take it that your Dr will be keeping a close eye on you to see how things are going. All medications can have possible side effects, even aspirin. If you have high BP you need to give this med a try. If you have any unusual side effects give your Dr a call.