As scorching heatwaves ravage the United States, millions of Americans were recently instructed to do something really out of the ordinary by the National Weather Service: don’t consume coffee. This advice, impacting eleven states nationwide, is a drastic departure from public health advice issued during times of hazardous heat.
The eleven states under coffee restrictions
The National Weather Service has also issued extreme heat warnings and advisories in eleven states where coffee is not advisable to consume as it is extremely hot there. They include:
States with extreme heat warnings:
- California (up to 110°F in valleys)
- Nevada (Las Vegas area reaching 110-115°F)
- Arizona (lower Grand Canyon regions up to 115°F)
- Utah (about 110°F in Washington County and in Zion National Park)
- Oregon (up to 110°F in western Siskiyou County)
States with heat advisories:
- Washington
- Idaho
- Louisiana
- Mississippi
- Florida
- Georgia
Death Valley, often known to be one of the hottest spots on the planet, is predicted to set all-time highs of 120-125°F during heat waves.
The scientific reasoning behind nor drinking coffee
The biggest issue with drinking coffee during hot weather is caffeine’s diuretic effect. Caffeine is a weak diuretic and increases urine production from the kidneys. Increased loss of fluids becomes problematic during heat waves because the body has already lost so much water in the form of sweat.
Studies have shown that 300mg or greater amounts of caffeine (about 3 cups of coffee) can cause acute diuresis, particularly among non-caffeine habituates. For comparison, a normal 8-ounce serving of coffee provides 80-100mg of caffeine.
Dehydration risks during heat waves
In hot conditions, the human body loses 500ml to 10 liters of water in a day through sweat, depending on activity and environmental levels. When combined with caffeine’s diuretic effect, this can accelerate dehydration and heat disease risk.
Dr. Donald Grant, a clinical senior advisor at The Independent Pharmacy, explains: “The caffeine has a diuretic effect, increasing urination and stripping the body of necessary fluids. If they’re not then replaced with suitable rehydration, people can get ill or more susceptible to ending up with a heat-related illness.”
Heat-related health complications
The National Weather Service issued the warnings specifically because extreme heat is the number one annual weather-related cause of death among all weather hazards. Heat illness can quickly escalate from heat exhaustion to life-threatening heat stroke.
Symptoms of heat exhaustion include:
- Heavy perspiration
- Dizziness and headaches
- Nausea and vomiting
- Weak, fast pulse
- Cool, damp skin
Symptoms of heat stroke include:
- Body temperature over 104°F
- Confusion and change in mental state
- Hot, dry skin (no sweating)
- Strong, fast pulse
- Loss of consciousness
The role of vasoconstriction
Aside from dehydration issues, caffeine is also a vasoconstrictor or makes blood vessels constrict. In hot weather, the body depends on effective circulation of the blood to lose heat by way of the skin. Constricted blood flow may lower the body’s normal cooling mechanisms, increasing the risk of heat-related disease.
But registered dietitian Brigitte Zeitlin explains that for coffee to have a noticeable impact on blood vessels, it is up to three things: sensitivity to caffeine, amount consumed, and health history.
Specialist guidelines and alternatives
Health professionals advise dramatically increasing fluid consumption in heat stress situations. Dr. Grant suggests consuming 2.5-3 liters of fluid a day during heat waves. The CDC advises drinking 8 ounces of water every 15-20 minutes while working outdoors in the heat, or approximately 24-32 ounces per hour.
Hydrating coffee alternatives
- Plain water (the hydration gold standard)
- Electrolyte-containing sports drinks
- Coconut water (high in electrolytes and potassium naturally)
- Fruit-infused water
- Cold-brew herbal tea
- Buttermilk (electrolyte balance)
Dietary foods for hydration:
- Watermelon (more than 90% water)
- Cucumber
- Tomatoes
- Strawberries
- Bell peppers
- Celery
- Lettuce
For those who cannot forgo their daily coffee, experts suggest modifications rather than complete avoidance. Registered dietitian Natalie Newell recommends drinking 12-24 ounces of water for every 12 ounces of coffee consumed. Additionally, timing matters – consuming coffee during cooler parts of the day and pairing it with adequate water intake can help mitigate risks.
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