When you're on vacation, the last thing you expect to happen is to wake up in a foreign hospital, unsure of how you got there. This has unfortunately been the case more than once at resorts in Mexico lately, where visitors claim their drinks have been made with "tainted" or "substandard" alcohol.After a series of frightening and sometimes deadly incidents at resorts in Mexico, the U.S. State Department issued a warning last Wednesday that "consumption of tainted or substandard alcohol has resulted in illness or blacking out." The incidents have occurred to both teenagers and adults near Cancun and Playa del Carmen. One Wisconsin family lost their daughter, 20-year-old Abbey Connor, in January, USA Today reported. Just hours after arriving on vacation, Abbey and her brother Austin were found face-down in the pool. Their son had a concussion but thankfully survived.The family still doesn't have a clear picture of what happened that day, but believes the kids were drugged. Similar incidents have occurred at other resorts within the Iberostar group, though thankfully no other deaths have been reported. In another instance, a woman from Iowa staying at the Iberostar Cancun with her husband and two kids had one shot and half a mixed drink before blacking out and winding up in a hospital. Her husband says before they got her there, she was unable to get out of the pool and started seizing, something that had never happened to her before. She too believes her drink was drugged.The problem may well lie in the alcohol itself, though. A 2015 report from the Tax Administration Service in Mexico said that 43% of all the alcohol consumed in the country is illegal, produced without regulations, USA Today reports. Government reports caution that this alcohol could be made with grain alcohol or dangerous concentrations of methanol.In a statement, Iberostar said the company adheres to strict regulatory standards and only purchases "sealed bottles (of alcohol) that satisfy all standards required by the designated regulatory authorities."After reporting on Connor's death, the Milwaukee Journal Sentinel heard from more than three dozen people claiming similar experiences after drinking small amounts of liquor at resorts in Mexico.In a statement to the Milwaukee Journal Sentinel, a representative from the U.S. State Department said this: "Following these reports and in consultation with our Posts in Mexico, we updated our Country Specific Information for Mexico to provide updated safety information regarding potentially tainted alcohol."The U.S. State Department urges those who wish to drink in Mexico to do so in moderation and to seek medical attention immediately if they start to feel sick.