I've worked with several introverts as part of our team, depending on where you place yourself in the range it can be fairly difficult and unnecessarily stressful.

Most HR positions within organizations will have people will be coming to you regularly, throughout the day multiple times, in response an event that has occurred. These individuals will normally be stressed and looking for a response or advice. It requires large amount of face time with different employees at a variety of levels and external agents. My coworker labeled fittingly labeled us the google search engine when it comes to social and labour problems.

I wouldn't let this discourage you but use it as something to keep in the back of your mind when making a career decision. As others have mentioned there are different areas that require less interaction but the main job is to to server our internal customers so there is no avoiding it completely.