It looks like MannKind Corporation might have a shiny new superstar on its hands. The drug company’s new darling, inhalable diabetes drug Afrezza, certainly looks like a blockbuster waiting to happen.

It’s got it all, a novel new delivery system (“Look Ma, no needles!”), 25 million potential customers in the United States alone, and—best of all—a brand spanking new “APPROVED”stamp courtesy of the folks over at the Food and Drug Administration.

You might even say Afrezzas future’s so bright MannKind has got to wear shades.

But even as investors don party hats, and MannKind breaks out the bubbly, there’s a dark side to Afrezza. An ugly monster lurks in the shadows, and no one wants to talk about it.

The potential side effects from taking Afrezza are so serious that it’s earned itself a black box warning from the FDA.

It’s just too bad that black boxes don’t amount to a hill of beans these days.

Shocked? Don’t be. There was a time when a black box on your label—the most serious warning the FDA can give—was like the kiss-of-death for a new drug. But lucky for MannKind (and unlucky for us) their effectiveness has faded away like a photo left out in the sun too long.

These days most docs pay little attention to them. Some just ignore them altogether. Top-selling diabetes drug, metformin (Glucophage), carried a black box warning for years. It never hurt sales.

Blockbusters Warfarin, Abilify, Cipro and even over-the-counter Tylenol are all currently sporting their own ineffective black boxes. And really it’s no wonder. Despite the name, a black box warning amounts to nothing more than an easily-overlooked thin black line drawn around some words on the label.

 Afrezza may be bad news for your lungs

Afrezza’s black box has to do with the drug’s link to potential breathing problems. The FDA…you know the keystone cops who just gave Afrezza their blessing…has admitted that the drug’s tied to a decline in lung function.

In fact, Afrezza is linked with potential bronchial spasms similar to those seen with asthma! In some patients the coughing became so bad they stopped treatment. And the drugs prescribing information warns if you have asthma, COPD, are a smoker, or have recently quit smoking, Afrezza’s definitely NOT for you.

And then there are the questions about just how well the drug actually works.

In a head-to-head test with injected insulin Novolog, Afrezza didn’t lower blood sugar as well. It also did worse at achieving less than 7 percent or 6.5 percent A1c (an important measure of how well you’re managing your diabetes), and the mean fasting blood glucose level decrease was higher in Afrezza takers.

But there’s something worse lurking in those shadows…much, MUCH worse. To understand what that is we have to take a look at the history of inhalable diabetes drugs.

In 2006 Pfizer, another member of the Big Pharma posse, got approval for their own inhaled insulin drug. But Pfizer ended up pulling the product off the market because sales were so poor. (And drug giants Eli Lilly and Novo NorDisk dropped their development of inhaled insulin as well.)

But wait, what gives? An inhalable diabetes drug seems like a sure winner, right?

Inhaled insulins could come with a cancer risk

Well it probably would be if the drug’s potential side effects weren’t worse than the disease it’s being prescribed to treat. It turns out inhaling insulin directly into your lungs may not be such a hot idea after all. You see, insulin is a growth factor which is why Pfizer’s drug was associated with a higher risk of lung cancer.

Now it doesn’t take a genius to figure out that any other inhaled insulin could come with the same concern.

Heck, even the numbskulls at the FDA managed to figure that one out. They essentially admitted as much, when they suggested (yup, just a friendly “suggestion”since this is only lung cancer were talking about here) two post-market studies to evaluate Afrezza’s lung cancer risk.

You know what another name for post-market studies is? Human experimentation, because, let’s face it, that’s exactly what they are. Post-market studies turn US into human guinea pigs, and the cost could be your life.

I don’t have a crystal ball, so I can’t say for sure what Afrezza’s future holds. Whether or not it’s a blockbuster success for MannKind, and whether or not more serious risks will be revealed in the future, only time will tell.

But what I can say for sure is that the novelty of a new drug is never worth submitting to being a lab rat. And if your doctor tries to strong-arm you into becoming the next Afrezza guinea pig it’s time to find yourself a new doc, no matter how loudly the old one squeals.