Americans seeking a reprieve from blistering winter blues should stay alert as safety warnings grow amid a surge in murders in Mexico, an expert warns.

Former Drug Enforcement Administration (DEA) Special Agent Michael Brown, currently the global director of counter-narcotics technology at Rigaku Analytical Devices, told Fox News Digital that Americans must be on high alert when traveling to Mexico.

“If you leave the resort, you’re definitely at high risk, especially if you’re an American female,” he said. “You’re at risk of kidnapping or being sold into the sex trade. Anywhere in Mexico outside the resort is highly dangerous.”

Stephanie Snider, whose son, Jake, is Hull’s boyfriend, said in a series of Facebook posts that Hull and Pitze were slipped a drug while they were at the resort in Cancun.

“What started out as a fun vacation with friends for them ended up as our worst nightmare,” Snider wrote.

Tourists walk on a beach in Playa del Carmen, Mexico, on July 11, 2017. (Brett Gundlock/Bloomberg via Getty Images)

After leaving the pool, Jake explained that Pitze was taken back to their room in a wheelchair, while he carried Hull. Hull began throwing up and having what he thought was a seizure. 

“Zara started having what the resort doctor called a ‘seizure’ and said she needed to be taken to the hospital. Once she was there, the hospital demanded $10,000 just to look at her to help her and start treating her. The money was sent. By the next morning, we were told more money was needed to continue treatment,” Snider said.

Snider said Pitze did not end up in the hospital but struggled the following day after the incident.

“Neither of the girls have any memory of what happened after they took that last drink, which happened to have been a glass of WATER. We think it was whatever was put in that glass of water that did it. Both girls collapsed at the very SAME time. They both are battling feelings of not knowing what happened and ‘why them?’” Snider said. 

Nearly 27 hours later and after spending thousands of dollars, Hull’s family was able to negotiate with the U.S. Embassy and have her flown to Dallas to continue medical treatment. 

Fox News’ Peter Aitken and Bradford Betz contributed to this report.