The generic EpiPen is already causing some insurance companies to drop the real one

The introduction of a generic version of the life-saving — and expensive — EpiPen was heralded as a long overdue fix. But the move is now causing some insurance companies to change how they approach coverage of the allergy tool.

The insurer Cigna on Thursday said the company would no longer cover the full-price EpiPen, which costs as much as $600. Those prices sparked outrage last summer when customers with high-deductible healthcare plans were caught off guard by the high prices for a once-reasonable healthcare need. The pharmaceutical company Mylan bought the rights to the EpiPen in 2007 and systematically raised the allergy tool's prices over the following nine years.

Mylan introduced its generic version of the EpiPen in December in response to public outcry. The generic costs half as much as the brand-name product.

"The generic version, available now in pharmacies, has the same drug formulation and device functionality as the branded medication, but at a substantial cost savings," Cigna spokeswoman Karen Eldred told CNN Money.

Before December, there hadn't been a generic version of the EpiPen. That was because the product's patented technology is the pen itself, rather than the active drug epinephrine. Even slight differences in how the pen works to inject epinephrine could be critical when a person is going through anaphylactic shock, so pharmaceutical companies were reluctant to introduce alternate versions.

Mylan told CNN Money that it anticipated its introduction of a generic version would change how insurers cover the EpiPen.

Meanwhile, CVS Pharmacy said on Thursday that it would sell a generic version of an EpiPen competitor for $109.99 — a price that comes close to what EpiPens cost when Mylan bought the rights in 2007, and is far less than Mylan's $300 generic.

That product is the generic version of the Adrenaclick, not Mylan's EpiPen.