Can green tea cause diarrhea? 

In this article, we will answer the question “Can green tea cause diarrhea?”, and discuss the reasons explaining why green tea can cause diarrhea.

Can green tea cause diarrhea?

Yes, green tea can cause diarrhea if consumed in large amounts. Compounds present in green tea, including caffeine, flavonols, and strictinin, have been found to have laxative effects. 

Flavonols, caffeine and strictinin increase the gut movements or stimulate the relaxation of the colon, resulting in more trips to the bathroom. Especially pu´erh tea has healing effects against viral and microbial infections as well as the laxative effect on defecation (2,8).

Why can green tea cause diarrhea? 

Green tea has a laxative effect on the gastrointestinal system of the body because of the effect of the chemical compound strictinin and flavonols, which is present in the green tea (2,7).

Studies  demonstrated that strictinin possesses a laxative activity on rat defecation. According to our animal studies, the laxative activity of strictinin was presumably caused by accelerating small intestinal transit. Strictinin is a hydrolyzable tannin found in green tea leaves (2). 

Flavonoids are polyphenols, substances with strong antioxidant properties and biological effects, also known to increase gastric motility and possess a laxative effect. The most important flavonols in green tea are the catechins epicatechin, epicatechin-3-gallate, epigallocatechin and epigallocatechin-3-gallate (7).

In addition, the caffeine in green tea contains, which in the amount of ~3% enhances the autonomic activity of the vagus nerve, promotes gastrointestinal motility (8).

What are the gastrointestinal effects of green tea?

The flavonoids present in green tea have several effects on the gastrointestinal tract, including (8):

  • Protect the intestinal mucosa against damage caused by food toxins;
  • Regulate the activity of enzymes involved in the absorption of lipids and carbohydrates
  • Regulate the secretion of intestinal hormones
  • Modulate the immune system of the gastrointestinal system
  • Protect the colon from tumor formation
  • Modulate the composition of the bacterial flora

The compound strictinin, a tannin, has the following effects on the gastrointestinal tract (2):

  • Promotes gastric emptying and accelerates the small intestinal transit
  • Has inhibitory effects against bacteria, such as Propionibacterium acnes and Staphylococcus epidermidis
  • Has  antiviral, anti-allergic, and immunostimulatory effects

Caffeine, an alkaloid, has the effect of promoting motility by enhancing the autonomic activity of the vagus nerve (8).

Can you use green tea to treat constipation?

Yes, you can use green tea to treat constipation. A study showed that the water extracts of green tea promotes gastric motility and was successfully used to treat constipation of patients suffering from irritable bowel syndrome (8). 

However, drinking green tea in excess can lead to diarrhea, especially in the case of the  Pu’er tea, which is produced from young leaves of tea (2).

How much green tea can you drink per day?

The safe amount of green tea to be consumed in a day may vary depending on many factors, such as age, body weight, genetic characteristics and individual tolerance for caffeine and the properties of the tea itself. 

In order to have the beneficial effects of green tea, depending on the brand, two to three cups of green tea is recommended per day.

It is recommended to drink no more than 5 cups per day and a higher consumption may cause insomnia, restlessness and upset stomach, dehydration and other negative effects. However, it has been reported that Japanese women could drink over nine cups in a day (7).

What are the possible side-effects of drinking green tea to promote gastric motility? 

The side effects of drinking large quantities of green tea are associated with the negative effects of caffeine and catechins, when ingested in high amounts. In addition, green tea can cause gastrointestinal discomfort. The following side effects of green tea are explained below:


The caffeine content of green tea can trigger headaches in people suffering from migraines or frequent headaches (7).

Troubled sleep

The caffeine in green tea inhibits the production of melatonin, depriving the person of sleep. The symptoms are worse for caffeine-insensitive people. 

Caffeine is a stimulant which may cause insomnia; may worsen ulcer symptoms; increase heart rate and blood pressure – effect lessens with regular use; high doses of caffeine are toxic; chronic use leads to tolerance, psychological dependence, habit forming; abrupt cessation results in withdrawal symptoms (5).

Iron deficiency

The tannins in green tea inhibit the absorption of iron from the gut. This is particularly dangerous for anemic people. To solve this problem, add lemon to your tea or drink at least 1 hour after or before a meal. Tannin can contribute to iron deficiency, impaired iron metabolism and macrocytic anemia in infants (5).


Due to excessive green tea intake, the tannins can cause nausea, constipation, and vomiting. Limit its use to 1-2 cups per day. Loss of appetite, abdominal bloating/pain, dyspepsia, flatulence and diarrhea are other side effects reported that are caused by the use of green tea (7).

Liver disease

When consumed in excessive amounts, the caffeine in green tea can damage the liver. Very rare reports of liver damage from concentrated green tea extracts (rather than tea infusions or beverages) suggest take with food and discontinue use if symptoms of liver disorder develop (abdominal pain, dark urine, jaundice) (5).

A risk for pregnant women

Drinking green tea in excessive amounts can lead to miscarriage and birth defects in newborns while compromising the health of the mother. It should be consumed in moderate amounts due to the presence of tannins, caffeine, and tea catechin. Caffeine crosses placenta and is associated with spontaneous abortion at doses over 100 mg/day (5).

Other side-effects

The caffeine in green tea can cause anxiety and affects blood sugar levels. Therefore, people with anxiety and diabetes should limit their use of green tea. Green tea may cause an increase in blood pressure when taken with propranolol/metoprolol. Green tea can also lead to skin conditions like eczema and hives to allergic people.

Drinking tea and coffee is related to higher incidences of acid reflux disease, while the tea, due to its antioxidant effect, can be used as a therapy for healing ulcers or other gastrointestinal disorders (3). As a precaution, never drink green tea on an empty stomach and limit its consumption to only one cup per day.

Drinking tea is basically safe and does not have many contraindications. It is important to use it wisely while pregnant or for the elderly.  Adverse effects related to green tea consumption are mostly related to gastrointestinal disturbance, such as primary nausea, abdominal pain or discomfort, diarrhea, dyspepsia/indigestion and/or elevated liver enzymes (4).

Other FAQs about Tea which you may be interested in.

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What are the benefits of drinking green tea?

Epigallocatechin gallate (EGCG), l-theanine, potassium, iron, calcium, and caffeine are some of the bioactive compounds of green tea. Green tea provides 29 mg of caffeine per cup of brewed beverage.

Helpful for weight loss

The caffeine and catechins present in Green tea boost metabolism and promote the oxidation of fat cells, hence, aiding in weight loss.

Promotes mental alertness

The caffeine present in green tea, at the rate of 2-4%, helps in mental alertness. It does so by stimulating the heart, muscles, and brain to release neurotransmitters. It also promotes urine production. It also helps to prevent Alzheimer’s and Parkinson’s’ (6).

Protects against heart diseases and cancer

Green tea contains some flavonoids namely; epigallocatechin gallate, or EGCG, that have excellent antioxidant properties. These antioxidants fight free radicals and protect the body against heart diseases. It also lowers the LDL and improves the blood flow in vessels to prevent the risk of heart diseases.

The polyphenols present in green tea have anti-inflammatory properties and could reduce the risk of various side effects caused by chemo- and radiotherapy (4). 


In this article, we answered the question “Can green tea cause diarrhea?”, and discuss the reasons explaining why green tea can cause diarrhea.


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  2. Hsieh, Sheng-Kuo, et al. Antibacterial and laxative activities of strictinin isolated from Pu’er tea (Camellia sinensis). j food drug anal, 2016, 24, 722-729.  
  3. Truong, Van-Long, and Woo-Sik Jeong. Antioxidant and anti-inflammatory roles of tea polyphenols in inflammatory bowel diseases. Food Sci Human Wellness, 2022, 11, 502-511.
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