A pharmaceutical company is facing criticism for increasing the price of a lifesaving injection used to reverse a potentially deadly allergic reaction.

A two-pack of EpiPens used to cost about $100. But after a competitor took a similar product off the market, EpiPen maker Mylan Pharmaceuticals increased the price to around $600.

Doctors say that those who use EpiPens are starting to suffer from the cost increase. They say it is especially true among those with high deductibles or no health insurance.

"It's has been really quite shocking for patients," says New Jersey allergy specialist Dr. Donald Leibner. "I've actually have a lot of patients who have separated those two-packs and they give one to the school, one to the parents because they could only afford to buy one two-pack so that becomes potentially life-threatening."

Mylan blames the price increase on the changing insurance landscape. The company says in a statement, "the change to the industry is not an easy challenge to address, but we recognize the need and are committed to working with customers and payers to find solutions to meet the needs of the patients and families we serve."

Mylan says that the company offers a savings card and a coupon for the item.

The nonprofit group "Allergy and Asthma Network" is working to get the EpiPen placed on a preventative medicine list, so that health insurance companies will be forced to cover it.