Can I Drink Green Tea That Has Been Left Out?

December 1, 2025 •

4 min read

According to food safety guidelines, brewed tea should not be left at room temperature for more than eight hours. This is because the lukewarm temperature creates an ideal environment for bacteria to grow, so drinking green tea that has been left out poses a health risk and will have degraded flavor and nutritional value.

Quick Summary

Brewed green tea left at room temperature for extended periods becomes a breeding ground for bacteria, risking foodborne illness. Over time, the tea loses flavor, aroma, and beneficial antioxidants. Proper refrigeration is essential for safe storage, typically for up to 48 hours, while any tea left out for more than eight hours should be discarded to avoid contamination. Flavor and safety are compromised with improper storage.

Key Points

Limited Lifespan: Brewed green tea should not be consumed if left at room temperature for more than 8 hours due to bacterial risks.
Bacterial Hazard: The warm, moist conditions of brewed tea left out create an ideal environment for harmful bacteria to thrive, potentially causing food poisoning.
Quality Degradation: Extended exposure to air diminishes green tea’s flavor, aroma, and antioxidant content, resulting in a dull, bitter taste.
Reheating Doesn't Help: Reheating old, brewed tea does not eliminate all bacterial risks and further degrades its quality and nutritional value.
Proper Storage is Key: For safe consumption beyond a few hours, brewed green tea must be stored in a sealed, airtight container in the refrigerator and discarded after 2 days.
Discard When in Doubt: If the tea appears cloudy, smells sour or musty, or tastes off, it should be thrown away immediately.

Risks of Drinking Brewed Green Tea Left Out

While you might be tempted to finish that cup of green tea from your desk the next morning, doing so can compromise both your health and the tea's quality. When brewed green tea is left at room temperature for an extended period, it enters what food safety experts call the 'temperature danger zone'. This warm, moist environment is a perfect breeding ground for various bacteria, including common foodborne pathogens.

Bacterial Growth

The primary risk of drinking green tea that has been left out is the potential for bacterial contamination. Even though green tea contains some natural antibacterial properties, it is not immune to contamination over time. Leaving the tea exposed allows microorganisms from the air and surrounding surfaces to enter and multiply to dangerous levels. Sweetened tea or tea with milk is even more susceptible to rapid bacterial growth due to the additional sugars. Drinking tea contaminated with harmful bacteria can lead to gastrointestinal issues, such as nausea, vomiting, and diarrhea.

Degradation of Flavor and Nutrients

Beyond the safety concerns, the quality of green tea degrades significantly when left out. Green tea's delicate flavor profile, rich aroma, and high antioxidant content are highly sensitive to environmental factors like heat, light, and oxygen.

Loss of Antioxidants: Green tea is celebrated for its antioxidant properties, particularly catechins like EGCG. Reheating or simply leaving the tea out causes these delicate compounds to break down, destroying their beneficial effects.
Increased Bitterness: Exposure to air for prolonged periods causes the polyphenols, such as tannins, to oxidize and release into the brew. This results in a bitter, astringent, and often unpleasant flavor.
Stale Aroma: The volatile compounds responsible for green tea's fresh, fragrant aroma dissipate over time. An old cup of tea may smell dull, musty, or just 'off'.

Risks Associated with Reheating

If your intention is to reheat the tea, be warned that this does not eliminate the risks. Reheating tea that has already been contaminated with bacteria may not kill all pathogens, especially those that form heat-resistant spores. Reheating also further accelerates the loss of flavor and nutrients. For the best and safest experience, it's always recommended to brew a fresh batch.

Guidelines for Safe Tea Consumption

Follow these best practices to ensure your brewed green tea is both delicious and safe to drink.

Time is Critical: A good rule of thumb is to consume brewed tea within 4–6 hours if left at room temperature. After 8 hours, the risk of bacterial growth increases significantly, and it should be discarded.
Refrigerate Immediately: If you wish to save leftover green tea, transfer it to a clean, airtight container and place it in the refrigerator as soon as it has cooled. Refrigerated, it will remain safe and palatable for 24–48 hours.
Watch for Spoilage Signs: Always inspect your tea before drinking. Signs of spoilage include a cloudy appearance, off-putting odors (musty or sour), or a bitter, flat taste.
Brewing Fresh is Best: For optimal flavor and nutritional benefits, it's always best to enjoy your green tea freshly brewed.

Comparison Table: Room Temperature vs. Refrigerated Green Tea


Feature	Brewed at Room Temperature	Brewed and Refrigerated
Shelf Life	Maximum of 4–8 hours	Up to 48 hours
Bacterial Growth	High risk after a few hours, especially with additives	Significantly slowed, but not eliminated
Flavor	Quickly becomes stale and bitter due to oxidation	Retains flavor and freshness for longer
Nutritional Value	Antioxidants degrade rapidly with heat and time	Preserves beneficial compounds at a slower rate
Safety	Not recommended for consumption after 8 hours	Safe to drink for 1–2 days, but inspect for spoilage

Conclusion: The Final Verdict

In summary, while drinking green tea that has been left out for a very short time may be harmless, it is never advisable to consume it after it has been sitting at room temperature for more than 8 hours. The risks of bacterial contamination, coupled with the inevitable degradation of flavor and nutrients, make it a poor and potentially unsafe choice. Always prioritize freshness by consuming your tea promptly or storing it properly in the refrigerator. For the best and most flavorful experience, and to reap all of green tea's health benefits, simply brew a fresh cup every time. When in doubt, throw it out—your digestive health will thank you.

For more detailed food safety guidelines, you can consult the Centers for Disease Control and Prevention (CDC).

Proper Storage Steps for Brewed Tea

Cool Down: Let freshly brewed tea cool to room temperature. Do not refrigerate hot tea as it can raise the temperature of other foods in the fridge.
Use an Airtight Container: Transfer the tea to a clean, airtight glass or ceramic container to prevent it from absorbing other food odors.
Refrigerate: Place the sealed container in the refrigerator and consume within 24-48 hours.
Label: Label the container with the date it was brewed to keep track of its freshness.

Frequently Asked Questions

Brewed green tea is best consumed within 4 to 6 hours when left at room temperature, though it is considered unsafe after 8 hours due to the risk of bacterial growth.

No, you should not drink green tea that was left out overnight. The prolonged period at room temperature, particularly in the temperature danger zone (41–135°F), provides a perfect environment for bacteria to multiply.

Drinking old green tea increases your risk of foodborne illness from bacteria like Salmonella and Bacillus cereus. You may experience symptoms like an upset stomach, nausea, or diarrhea.

No, reheating old green tea is not recommended. It will not necessarily kill all heat-resistant bacterial spores and further degrades the tea's flavor and beneficial antioxidant content.

You can tell by inspecting for signs of spoilage. These include a cloudy appearance, an unpleasant musty or sour smell, and a noticeably stale or bitter taste.

Cold-brewed tea is not immune to bacterial growth. While some methods can be safe if immediately refrigerated, any brewed tea, regardless of method, should not be left out at room temperature for extended periods.

The best way to store brewed green tea is in a clean, airtight container in the refrigerator. Consume it within 24–48 hours for optimal safety and flavor.

Dried green tea leaves or tea bags have a 'best by' date, after which the flavor and aroma will diminish, but they don't expire in the sense of becoming toxic unless exposed to moisture and contaminated with mold.