An investigation by the Milwaukee Journal Sentinel is raising questions about drinking at all-inclusive resorts in Mexico. According to the report, people at certain resorts are blacking out and becoming ill after consuming allegedly tainted alcohol.

Last year, a Wisconsin woman died after being served drinks, and the Journal Sentinel found numerous other cases of suspicious blackouts at Iberostar Mexico all-inclusive resorts.

The U.S. State Department acknowledged the incidents on its Mexico travel information page under the “Safety and Security” section. The department states: “There have been allegations that consumption of tainted or substandard alcohol has resulted in illness or blacking out. If you choose to drink alcohol, it is important to do so in moderation and to stop and seek medical attention if you begin to feel ill.”

However, some of the people the Journal Sentinel spoke with lost consciousness after only a drink or two.

If you’re traveling to Mexico, here are a few suggestions to make sure you stay safe.

Moderate consumption: Drinking in moderation is always important, especially in places or countries you’re unfamiliar with.

Purchase recognized brands: Rather than drinking bottomless drinks or specials, buy sealed bottles from brands that you know and trust from reputable retail stores. The Journal Sentinel found that people reported illnesses after drinking various types of alcohol from tequila to rum to beer.

Know what’s in your drink: If you’re at a bar, order drinks using specific brand names and watch how much alcohol is poured in when the drinks are made. A sealed beer is the safest option.