1. Put a handful of tea leaves in a cup and drink it from morning till night.

You claim you don't have time to use proper tea tools, so you use one cup and one handful of tea leaves all day.

A cup with a large amount of tea results in high concentration. Tea leaves contain 2% to 5% caffeine. A strong cup of tea contains about 100 mg of caffeine. Excessive caffeine can overstimulate the nerves, causing insomnia; it can also accelerate heartbeat, increasing heart burden. The heightened excitability of the central nervous system can speed up stomach motility, increase gastric acid, and intensify irritation to the gastric mucosa, leading to stomach ulcers.

Strong tea also contains more tannic acid. Tannic acid can bind with proteins, vitamin B1, and iron ions in food, preventing these nutrients from being properly absorbed, which may lead to deficiencies and related symptoms like anemia and constipation.

Additionally, caffeine can be addictive, creating a vicious cycle. Don’t say weak tea is tasteless or that you’re used to it. For the sake of your health, quit this bad habit now.

2. Drink tea when hungry, and drink tea when full.

When hungry, the stomach is empty. Drinking tea on an empty stomach dilutes gastric acid and inhibits gastric juice secretion, hindering digestion. It may even cause symptoms like palpitations, headaches, stomach discomfort, dizziness, and irritability—known as "tea drunkenness"—and affect protein absorption, potentially causing gastritis.

It is also not advisable to drink tea within half an hour after meals because tea dilutes gastric juice, affecting food digestion. Moreover, tea contains oxalic acid, which reacts with iron and protein in food, reducing the body’s absorption of these nutrients.

3. A cup of tea first thing in the morning.

There’s a saying: "A cup of tea in the morning starves the pharmacist’s family." Drinking tea immediately after waking up, on an empty stomach, can cause various discomforts. Those with a cold constitution are especially prone to stimulation, leading to physical unease. Thus, having tea first thing in the morning is wrong; wait until after breakfast.

4. Can’t bear to throw away unfinished tea, so drink it the next day.

Tea should be consumed fresh. Leaving tea steeped for too long not only causes loss of vitamins and other nutrients but also allows proteins and sugars in the tea to become breeding grounds for bacteria and mold, leading to spoilage. If you can’t bear to waste it, use it for watering plants or cleaning furniture—it has many uses.

5. Replace water with tea.

Although tea is very effective at quenching thirst, it cannot replace water. You cannot assume that drinking tea daily eliminates the need for water. Moreover, daily tea consumption should not exceed 10 grams. Experts estimate that each gram of tea contains about 200 mg of tea polyphenols. Assuming you drink 6 grams of tea daily, after two infusions, the tea may contain 1200 mg of tea polyphenols. If the body’s absorption rate is 50%, you intake about 600 mg. Since just 300 mg of tea polyphenols daily is sufficient for health benefits, drinking 6 to 10 grams of tea per day is adequate.

6. Use tea to sober up or take medication.

Tea stimulates the central nervous system. Drinking strong tea after alcohol intoxication increases heart burden. Tea also accelerates diuresis, causing toxic aldehydes from alcohol to be excreted by the kidneys before being broken down, which can harm kidney health.

There are many types of drugs with different properties. Tannins and theophylline in tea can react chemically with certain medications, so tea should not be used to take drugs, as it may reduce efficacy. Some Chinese herbal medicines should also not be taken with tea. Generally, avoid drinking tea within two hours of taking medication.