Even Martin Shkreli, the disgraced former chief executive of Turing Pharmaceuticals, has weighed in.
"These guys are really vultures. What drives this company's moral compass?" he told NBC News in a phone interview.
In 2015, Shkreli famously jacked up the price of Turing's malaria and HIV medicine Darapim overnight, from $13.50 to $750, a move that earned him a grilling by the House Committee on Oversight and Government Reform in February — and the nickname "Pharma Bro" for his seemingly carefree attitude toward affordable medication.
But Shkreli told NBC News he had originally considered gradually raising the price of Darapim, as Mylan did with the EpiPen. Ultimately, "the math, we felt, was a little silly; so we decided to come out and say 'This is our desired price.'"
The committee doesn't currently have an open investigation into the price of EpiPens, MJ Henshaw, a spokesperson for the committee chair Representative Jason Chaffetz, said in an email.
In response to NBC's story earlier this week, Senator Bernie Sanders sent out a tweet questioning the price increase.
Now there's a lawsuit in the works. Ari Kresch, CEO of 1-800-LAW-FIRM, said his firm was finalizing a filing against Mylan in the next couple of weeks.
"I've been looking at EpiPen for years," said Kresch. "It's a very cheap drug but I haven't been successful in getting any experts to tell me why the price has gone up as much as it has."
Mylan did not respond to phone or email messages seeking comment on the backlash.
In an earlier emailed statement, Mylan said its prices have "changed over time to better reflect important product features and the value the product provides," and that "we've made a significant investment to support the device over the past years."
The statement noted that commercially insured patients have successfully used its $100 coupon program, with nearly 80 percent of the My EpiPen Savings Card™ getting their auto-injectors for $0.
However, those without better insurance plans, or the uninsured, aren't able to take advantage of the program.
Dr. John Vann, a pediatrician in Omaha, Nebraska recalled the mother of a 14-year-old girl with walnut allergies crying in his office two weeks ago. She was on an HSA with a high deductible, and an EpiPen dual pack would have cost over $600. She didn't know how she would pay for it.
"You essentially have to have epinephrine around because if you have a reaction you need it," said Vann. "They hardly ever get used and it's a good thing — but if you don't have it, you're in trouble."
After doing some quick internet research, Vann was able to find "Adrenaclick," substitutable as a generic for EpiPen in 21 states, for just $200. The pharmacy was able to order it and have it available the next day.
Not all providers will cover it, though. He tried to do the same for another patient and the drugstore said that patient's insurance only pays for EpiPens.
"They did a pretty good job marketing themselves where it's just like Kleenex," said Vann. "People don't say 'epinephrine auto injector,' they say 'EpiPen.'"
Patients also expressed outrage in tweets and Facebook posts, and emails to NBC News.
Donna, an archaeology educator in Birmingham, Alabama who asked only her first name to be used, told how she felt her mouth, tongue, and eyes swelling shut after she was stung 26 times by yellow jackets on caving expedition a few years ago. That's when she learned for the first time that she was allergic. She hiked back several miles to her truck and sought treatment at the nearest hospital, two hours away.
"I barely survived and now have to carry two EpiPens at all times, even to the mailbox," she wrote in an email. "For Mylan to be the sole producer of this product and hold my life, and the millions of children and adult lives hostage for profit, is extortion and an outrage."