Chipotle Mexican Grill's stock price sank 2.7 percent Monday after "Supergirl" actor Jeremy Jordan said he had "almost died" from eating at one of the chain's restaurants.

Chipotle has been struggling for two years to move on from a string of high-profile foodborne illness outbreaks.

"I know I've advocated for them in the past, but they're terrible," Jordan said in the now-expired Instagram story, according to People magazine. "I, as you can see, am in the hospital and I have fluids in my arm because the food did not agree with me and I almost died."

"We were sorry to hear Jeremy was sick and were able to get in touch with him directly regarding where and when he ate," Chris Arnold, Chipotle's spokesman, told CNBC. "There have been no other reported claims of illness at the restaurant where he dined. We take all claims seriously, but we can't confirm any link to Chipotle given the details he shared with us."

It has been two years since a string of food safety incidents first battered sales and scared away diners. While the beleaguered burrito chain was able to return to profitability and its same-store sales have begun trending in a positive direction, its successes have been overshadowed by more recent incidents.

In July, reports surfaced that customers were sickened by norovirus at a location in Sterling, Virginia. Then, a few days later, a viral cellphone video was released that showed rodents falling from the ceiling at a restaurant near Dallas.

Both restaurants addressed these issues: The Virginia location shuttered briefly to sanitize, and the Texas restaurant sealed up the rodents' entry point.

Now, Chipotle's food safety policies are once again up for debate.

"If this is true then it is another potential PR disaster for Chipotle," Neil Saunders, managing director of GlobalData, told CNBC via email. "The chain has had a run of back luck with health scares and does not seem to be capable of getting back on an even keel. Each new issue reminds consumers of past problems and makes the prospect of a full recovery ever more distant."