If you’ve never heard of Adam Feuerstein, then you must not be in healthcare. For the un-initiated, Feuerstein is a columnist at The Street and writes about healthcare and biotech stocks. A decade or two ago, before the rise of social media, he wouldn’t have been that significant a player. Yet today he’s one of the most powerful voices in the industry.

I’ve seen company shares move simply by him tweeting a question about clinical trial data. He pretty much brought down the embargo policy at a major medical meeting a few years ago. Once, when I retweeted one of his posts about some bad news a company had, I got a call from the company’s CEO within the hour to make sure I understood their side of events.

He is also someone you don’t want to cross. Check out his twitter feed – it’s full of profanity and tear downs of drugs, companies, executives, business decisions and random people he happens to overhear talking at the hotel gym or at Starbucks. His feed can also be hilarious, and he says stuff lots of journalists think but would never write down anywhere traceable. You can easily freak out a biotech’s communications team by asking them, “hey, did you see what Adam tweeted about you guys?”

So what makes him so compelling and powerful? Well, like it or not, he speaks his mind. And he’s a self-professed skeptic, so a lot of what he says isn’t fluffy featurey bits but glass-half empty views. He’s also not afraid to antagonize investors who are particularly excited, sometimes unrealistically, about new drugs.

As a journalist at a top news company I got giddy whenever he mentioned me on twitter, even when he was trashing me. It meant that someone was paying attention, and frankly, I also hoped it would raise my social media profile.

What Feuerstein succeeds in is having a strong opinion (as a columnist, that’s his job) and broadcasts it freely on social media, no matter who he offends. This is something journalists can’t really do and exposes a weakness that the media face in an online world – a struggle to be relevant.

When it comes to social media, journalists are in a crux. Some actively seek to build their online reputations, others only linger long enough to post their own stories and still others choose to ignore it completely as a waste of time. The problem is, in order to get attention, you need to be interesting, which usually entails saying provocative things. But journalists also don’t want to expose any personal feelings on controversial topics, lest they be accused of having a “bias.” So they’re stuck tweeting their stories and talking about things not directly related to their beat.

Into that void stepped Feuerstein, and he has dominated it since.

While Feuerstein rules the healthcare social media world, he’s certainly not alone in wielding influence. The journalists that I greatly respected and paid attention to were bloggers and trade pub writers who are as prolific as they are smart. People like Luke Timmerman at Xconomy, Ron Leuty at the San Francisco Business Journal and Matt Herper at Forbes. They’re not as outspoken as Feuerstein, yet they also seem less constrained to speak their minds online than I at least felt as a journalist. And they often drive online conversations on industry topics, which can affect stock prices, investor perceptions, patients and other journalists.

This new dynamic is something everyone in the industry needs to understand.