Rick and Diana Neuenschwander of Symmes Township were having cocktails at a five-star all-inclusive resort in Mexico this month when they noticed something different about their final round of margaritas.

“It was just a little odd. They were different colors,” Rick said. “We ... just blacked out ... We just don't remember what happened.”

Rick said he believes the alcohol was tainted. And the couple isn’t alone.

Allegations of tainted or substandard alcohol that resulted in illness or blacking out have become serious enough that the State Department updated its Mexico page Wednesday, warning travelers to take extra caution when consuming alcohol. A 20-year-old Wisconsin woman also drowned in January at a five-star resort in Playa del Carmen, and her family told ABC News they suspect her drinks were somehow tainted.

The Neuenschwanders were at the Secrets Akumal Riviera Maya resort for a getaway over Independence Day. The resort is just south of Playa del Carmen where the Wisconsin woman drowned.

“We're standing in the pool, got our little floatie out, and we had some drinks. We were drinking some margaritas,” Rick said. “They were blowing bubbles in the pool. You got people dancing. It was Fourth of July in Mexico ... It was a lot of fun.”

Hours after having the "odd"-looking margaritas, Rick said he and Diana regained consciousness in their hotel room. He said they had no memory of what happened.

“We weren't drunk. We were out — completely different. If we stumbled, we have no idea that we stumbled. We don't know what happened,” Rick said, adding that he woke up with scratches on his face and that his wife had bruised shoulders. “My wife felt like she was maybe held down.”

Doctors and resort managers told them they’d simply had too much to drink and to enjoy the remainder of their time in Mexico, Rick said.

Resort General Manager Javier Estelrich said the Secrets Akumal Riviera Maya has a "strong track record for guest satisfaction" and the Neuenschwanders' conditions "had nothing to do with alcohol quality or staff service."

"There may be other factors to take into consideration," Estelrich said. "We can confirm that our staff took immediate and appropriate steps after being made aware that the couple was in need of assistance. This included escorting them safely to their room, getting them prompt medical attention by a licensed physician and ensuring their well-being.

"The health and safety of guests and staff at Secrets Akumal is always our top priority, and we strive to deliver exceptional vacation experiences. Our employees undergo mandatory training so they are equipped to recognize and respond effectively to health and safety concerns of our guests."

Estelrich also defended the resort's food and alcohol.

"We employ industry-leading operational policies and procedures to safeguard our food and beverage products from any tampering or contamination," he said. "In regards to alcohol, we only purchase and serve premium brand international and domestic top-shelf spirits from leading authorized suppliers to Mexico. This includes approved licensed and bonded vendors with whom we have long-term relationships and that meet the standards required by the designated regulatory authorities."

The Neuenschwanders' story sounds eerily similar to that of Corinne and Brian Kahny of Milan, Indiana. They honeymooned in 2015 at an all-inclusive resort in Negril, Jamaica, where they said they blacked out after three or four drinks at the pool.

"I believe it was one of the drinks," Corinne said. "We actually had them surprise us with (what it was), so me and my husband had the exact same drink. After that, I don't remember much."

Corinne said she and her husband came to in their room, hours later -- scared at what may have happened during the six blacked-out hours missing from their memories.

"We went down to the front desk. I was bawling my eyes out, and we told them that we think we've been drugged," Corinne said. "So they had this one security guy bring us back up to this room. He took a look at our room, (and) pretty much said that you were just drunk, passed out -- that we should get dressed and go to dinner."

Maureen Webster tracks similar stories on MexicoVacationAwareness.com, a website she started a decade ago when her son died after being pulled unconscious from a waist-deep resort pool.

The similar death of Abbey Conner at a Mexican resort in January now has her Wisconsin family shining a spotlight on tainted alcohol at these vacation spots.

According to a 2015 report from the Mexico Tax Administrative Service, 43 percent of all alcohol consumed in Mexico is produced illegally.

Over the past seven years, authorities from Mexico’s Federal Commission for Protection against Health Risk have seized 1.4 million gallons of bootleg liquor from hotels and bars they say could be infused with grain alcohol or methanol, both considered dangerous or even deadly.

“I think this is being swept under the rug,” Rick said, noting that he shared his resort experience with the U.S. consulate.

“She goes, ‘Well, have we had stories of tainted alcohol?’” And I said, ‘Well, I don't know that it was tainted. I feel like I was drugged. Now in hindsight and hearing some of the other stories, maybe it is tainted alcohol. I don't know,'” Rick said. “I think the government needs to look at this. I think they should look at a travel ban — a travel warning to Mexico whether it's drugs, whether they're calling it tainted alcohol. Whatever they want to call it ... something's going on in Mexico.”

Both Tri-State couples said it appeared their belongings had been rifled through, but they had secured their valuables in the room’s safe and found nothing missing.

The Neuenschwanders speculated they may have been targeted because they were not part of a large tourist group and they had just arrived the night before. They said perhaps a predator would think they hadn’t had time to secure their valuables since they would be so eager to get out and enjoy the resort on their first full day there. Concerned by the incident, they cut their trip short and changed their flights to return to Ohio the next day.

The Kahnys did not have a doctor check them or report the incident to police, and they remained on the resort for the rest of their trip without further incident.

"I just want people to be aware because if you go, you can't stop it unless you don't drink. Unless you check every single (alcoholic drink), which is impossible," Corinne said. "Because all day long they just bring you your drinks -- you don't see them make them."