23/08/2026
Heat injures the lining of your esophagus the same way it injures the lining of your mouth. The difference is what your nervous system tells you about it. The mouth has dense thermal pain receptors. The esophagus has visceral nerve endings that are tuned more to stretch than to temperature. You can swallow tea at temperatures that would burn your tongue without feeling pain. The damage is real but the warning signal isn't.
In 2016, the International Agency for Research on Cancer reviewed the evidence on hot beverages and esophageal cancer. They classified drinking beverages above 65°C as a Group 2A carcinogen, meaning a probable cause of cancer in humans. The mechanism is straightforward. Repeated thermal injury to the esophageal lining triggers chronic inflammation. Inflammation drives cell turnover. Faster cell turnover increases the rate at which mutations accumulate. Over years and decades, this combination raises the risk of esophageal squamous cell carcinoma.
The strongest data comes from the Golestan Cohort Study (Islami et al., 2019, International Journal of Cancer). Researchers prospectively followed 50,045 adults in northeastern Iran for a median of 10 years and recorded 317 new cases of esophageal squamous cell carcinoma. They measured tea drinking temperature objectively at baseline, not just by self-report.
The findings:
People who drank tea at 60°C or higher (objectively measured) had a 41% higher risk of esophageal squamous cell carcinoma than those who drank below 60°C. People who self-reported a preference for "very hot" tea (vs cold or lukewarm) had 141% higher risk. People who drank tea within 2 minutes of pouring had 51% higher risk than those who waited 6 minutes or more. People who drank 700 mL or more per day at 60°C or higher had about 90% higher risk than people who drank less at lower temperatures.
These findings are consistent across populations. Middleton and colleagues (2019, International Journal of Cancer) ran a separate case-control study in western Kenya, where esophageal squamous cell carcinoma incidence is also high. Drinkers of "very hot" beverages had 3.7 times the risk of warm-temperature drinkers. The association held after adjustment for alcohol and to***co use.
Two honest caveats. First, the IARC Group 2A classification means probable carcinogen, not confirmed carcinogen. Group 2A requires limited evidence in humans, sufficient evidence in animals, and a plausible mechanism. The temperature link is not as definitively established as Group 1 carcinogens like to***co. Second, the absolute risk for any one individual remains low. Esophageal squamous cell carcinoma is uncommon in most Western populations. The relative risk increases reported here are real but they apply to a baseline that's already small.
Practically: tea brewed at typical temperatures (85 to 95°C) cools below 65°C in roughly 4 to 5 minutes in a standard mug at room temperature. The exact time varies with cup material, volume, and ambient temperature. Letting tea cool for 4 to 6 minutes between pouring and drinking removes the temperature mechanism entirely. Coffee, hot chocolate, and any other hot beverage follow the same physics. The threshold is the temperature, not the drink.
The temperature is the variable. The drink isn't.
Islami et al., International Journal of Cancer, 2019 Middleton et al., International Journal of Cancer, 2019 IARC Monograph Volume 116, 2018
