Do not drink overnight tea.
Overnight tea loses most of its vitamins over time. Proteins and sugars in the brew become nutrients for bacteria and mold growth, so it's generally considered undrinkable.
Tea generally remains in the body for about three hours, while strong tea lingers longer. This allows excessive accumulation of theine, potentially disrupting nervous system function. Stored tea not only loses nutrients like vitamins but also spoils easily. Moreover, the tannic acid in tea can oxidize into highly irritating compounds that harm the spleen and stomach. This is especially problematic in summer, when it may trigger gastrointestinal inflammation.
In the past, poorly sealed containers could allow poisonous insects to fall into or crawl through water, potentially rendering it highly toxic. Ji Xiaolan's Notes from the Reading Micro Studio records such an incident: During summer, a woman bathed her two children at night. Leftover tea from the day sat on a nearby table. Thirsty, the children drank it.Before long, the children vanished, and the bathwater turned murky and foul-smelling. Thus, since ancient times, overnight tea has been forbidden, as lizards mating near water at night could contaminate it with highly toxic semen. Overnight Tea Has Other Uses I. Beauty Tips 1. Promotes Eyelash Growth.Let leftover tea cool, then use a cotton swab to apply it to your eyelashes before bed or the next morning. This promotes lash growth—try it now! It's a highly effective and economical "lash growth serum."
2. Reduces dark circles. Apply used tea bags as warm compresses on your eyes to diminish dark circles!
3. Sun protection.If your skin gets sunburned, gently wipe it with a towel soaked in overnight tea. The flavonoids in tea have anti-radiation properties.
II. Health Benefits
Stop Bleeding: For conditions like stomatitis, tongue abscesses, eczema, or bleeding gums, rinse your mouth with overnight tea. It can also be used to bathe areas with sores, boils, or skin bleeding.
Clear Eyes: The polyphenols in overnight tea have antibacterial and anti-inflammatory effects. If your eyes have redness, rinse them several times daily with overnight tea.
Relieve Itching: Wash affected areas with warm overnight tea to soothe itching.

Eye Clarity: The tea polyphenols in overnight tea possess antibacterial and anti-inflammatory properties. For redness in the eyes, rinse several times daily with overnight tea.
Itch Relief: Washing hair or wiping the body with warm overnight tea can quickly alleviate itching due to its fluoride content, which also helps prevent and treat eczema.
Hair Growth: Washing hair with overnight tea promotes hair growth and eliminates dandruff.For sparse eyebrows, brush them daily with a brush dipped in overnight tea. Over time, eyebrows will naturally become thicker and shinier.
Strengthen and Clean Teeth: The fluoride in tea combines with tooth enamel to enhance resistance against acidic substances, reducing cavities.fluoride also eliminates plaque. For best results, rinse your mouth with tea water two to three minutes after meals.
Freshens breath: Tea contains aromatic essential oils. Swishing a few mouthfuls of overnight tea before or after brushing in the morning, or after meals, leaves breath fresh. Regular tea rinses eliminate bad breath.
Removing fishy odors and grease: Leftover tea possesses exceptional properties for eliminating fishy smells and greasy residue. Washing hands with it after eating shrimp or crab leaves hands feeling exceptionally clean and refreshed.
Antibacterial treatment for athlete's foot: Individuals suffering from athlete's foot should boil tea leaves into a concentrated solution each evening for foot soaks. Over time, symptoms will subside without further treatment. Green tea is most effective for this purpose.
Caution: When using overnight tea, ensure it hasn't gone bad. In summer's high temperatures, tea easily sours and spoils. If left for over 24 hours, it's best not to drink it, as it may cause diarrhea.
III. Mold and Dampness Removal
In southern China, the stifling humidity and prolonged rainy season from June to July often leave wooden furniture and clothing covered in mold spots. This is where leftover tea proves invaluable.
Save leftover tea from daily use, dry it thoroughly, then seal it in cloth or kraft paper bags. Before the rainy season arrives, place these bags in areas prone to mold growth—such as shoe cabinets, under beds, or other wooden furniture—as well as in closets storing clothes and books, bedroom corners, and pillow stuffing.
On rare sunny days during the rainy season, expose the tea bags to direct sunlight. Once the moisture-absorbed tea bags dry out, return them to their designated spots. Repeat this process a few times. With the protection of these tea bags throughout the rainy season, you'll surely avoid mold and dampness, comfortably weathering this challenging time.
IV. Home Care
Dust on painted doors, windows, furniture, or glass surfaces can be wiped clean with cold tea leaves for a particularly bright and white finish.
New wooden furniture often emits a pungent paint odor. Wiping it down several times with tea water will naturally dissipate the smell more effectively than cleaning agents.
After discarding the overnight tea water and allowing it to drain slightly, place a cloth over the radiator pipe and evenly spread the tea leaves on top. Soon, the tea's fragrance will gradually fill the room with the rising steam. It's both eco-friendly and economical—why not give it a try?
V. Laundry Tips
New clothes or fabrics often carry a pungent, unpleasant odor from dyes. Burn a handful of tea leaves and use the smoke to neutralize the smell.
When brightly colored clothes fade, rinsing them in tea liquor can restore their original vibrancy.

Rinsing woolen garments with tea water effectively removes dirt while preserving their color brightness.

For oil stains on dark clothing, rubbing with used tea leaves can eliminate grime.
Washing woolen garments with tea water effectively removes grime while preserving vibrant hues.
Rub oily stains on dark clothing with used tea leaves to lift the dirt.
Silk fabrics dread chemical cleaners, but tea water maintains their original luster and freshness. The same effect applies to nylon fiber garments.