Hey, Food and Drug Administration! We all know that drugs can cause side effects in some patients. Can we just move on?

No?

I was afraid of that.

The agency's latest victim: Merck's (NYSE:MRK) Januvia and Janumet, the latter of which combines Januvia with another diabetes drug, metformin. On Friday, the FDA said it had received 88 reports of pancreatitis in the nearly two and a third years after Januvia was approved. So that's 88 out of how many people taking the drug? And how many of them would have gotten pancreatitis anyway? Those are the $2.4 billion (annually) questions.

In controlled trials with more than 6,000 patients, Merck says it hasn't seen any meaningful increases in pancreatitis over placebo. Keep in mind that diabetics have an increased risk of getting pancreatitis, so a controlled experiment is definitely the way to go.

The same problem of reported cases of pancreatitis in people taking Amylin Pharmaceuticals (NASDAQ:AMLN) and Eli Lilly's (NYSE:LLY) Byetta sank sales of their drug. Byetta and Januvia work in different ways, but ultimately on the same pathway, so it's possible there's a connection. If that's the case, then we'll have to throw AstraZeneca (NYSE:AZN) and Bristol-Myers Squibb's (NYSE:BMY) new diabetes drug, Onglyza, into the mix, as it's in the same class as Januvia.

From a clinical perspective, the problem with all these early warnings from the FDA is that patients and doctors may become desensitized to them.

For the companies, that might not be such a bad thing. It's not hard to imagine that the Januvia warning could actually increase sales of Byetta, as doctors who have had good experiences with Januvia, without any cases of pancreatitis, might also discount the potential pancreatitis issues with Byetta.

That's one side effect of these warnings that Amylin and Eli Lilly wouldn't mind seeing.

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Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. The Fool has a disclosure policy.