Doctors warn World Cup fans that alcohol raises heat illness risks

As millions of fans prepare to watch World Cup matches across the United States, Mexico and Canada this summer, health experts are warning that one common part of sports culture — drinking alcohol — can become more dangerous in extreme heat.

The concern comes as forecasters and public health officials continue to track hotter summers linked to climate change, with several host cities expected to face high temperatures and heavy humidity during June and July. Researchers say alcohol can worsen dehydration, raise heat stress and make it harder for people to recognize when their bodies are in trouble.

That risk is drawing attention not only inside stadiums but also at fan festivals, bars and outdoor viewing areas, where long hours in the sun, dense crowds and repeated drinking over several days can increase the strain on the body.

At a recent early morning soccer gathering at The Greyhound Bar & Grill in Los Angeles, fans packed the room for the Champions League final between Paris Saint-Germain and Arsenal. Less than 30 minutes into the match, patrons had already bought $1,300 worth of alcohol, according to the bar. For many supporters, drinking is part of the event.

But physicians and heat researchers say that habit can carry added risks in summer conditions. Alcohol affects the central nervous system and can cause dizziness, headaches, vomiting and loss of coordination. It also increases urination. When that is combined with sweating on a hot day, the result can be faster dehydration and a greater chance of heat-related illness.

Heat exhaustion happens when the body loses too much water and salt through sweating. Heat stroke, the more severe condition, occurs when the body can no longer cool itself. It can lead to confusion, loss of consciousness and death. Humidity makes matters worse because it reduces the body’s ability to cool through evaporation of sweat.

Experts say this combination may be especially relevant in host cities such as Miami, Houston and Monterrey, where heat and humidity can remain high for long stretches of the day.

Nathan Morris, an assistant professor who studies thermoregulation at the University of Colorado Colorado Springs, said alcohol can dull the normal impulse to cool down. People may stay outside longer, drink less water or delay moving into air conditioning because they feel relaxed or distracted rather than overheated.

Researchers have also found broader links between warm weather and alcohol-related harm. Studies from several countries show that alcohol consumption tends to rise in summer. A study from Mexico found that people living in hotter climates were more likely to binge drink. In New York state, a 2023 study found that higher temperatures were associated with more alcohol-related hospital visits.

Dr. Lorenzo Leggio, a physician-scientist at the National Institutes of Health, said heat and alcohol can have what he described as a synergistic effect. Sweating causes fluid loss, while alcohol leads to more urination. Together they can produce thirst, dizziness, headaches and confusion more quickly than either factor alone.

Fabiano Amorim, an associate professor at the University of New Mexico who has studied alcohol exposure in hot environments among construction workers, said his research found that drinking the night before could leave workers with elevated blood pressure, higher core and skin temperatures and increased heart rate the next day. Their urine and sweat production were also lower while working in heat.

Although soccer spectators are not doing heavy labor, Amorim said some of the same concerns apply because fans may spend hours outdoors in direct sun or crowded spaces with poor airflow. He also warned about cumulative effects during tournaments that stretch over days or weeks, especially for travelers moving from one match or viewing party to another.

Older adults, people with alcohol use disorders, those with heart disease and people with other chronic medical conditions are considered among the most vulnerable groups.

Public health specialists say the safest option in extreme heat is not to drink alcohol at all. For those who do choose to drink, they recommend eating beforehand, alternating alcoholic drinks with water, choosing beverages with lower alcohol content and avoiding excessive intake.

They also advise basic heat precautions before drinking begins: wear sunscreen and a hat, seek shade whenever possible and keep cold nonalcoholic drinks nearby. Shade can reduce heat stress on the body by 25% to 35% during the day and may be 20 degrees to 45 degrees Fahrenheit cooler than nearby unshaded surfaces, according to Amorim.

Experts also recommend using a buddy system so someone can respond if a person becomes disoriented or ill. Warning signs include dizziness, blurred vision, confusion and trouble seeing clearly. Medical staff are expected to be stationed throughout stadiums and fan festival sites during the tournament.

The warning reflects a broader challenge for organizers of major sporting events as hotter weather becomes more common. Soccer’s expanded World Cup schedule will bring 104 matches across North America this summer, increasing both attendance and exposure time for fans gathering outdoors during some of the hottest weeks of the year.

For bars, restaurants and beverage sellers near venues, that means strong business tied to game-day drinking. For health officials, it means pushing a message that celebration in extreme heat requires more caution than many fans may realize.