Green Tea Side Effects Warnings!
Advice To New Drinkers

Green tea side effects are easily preventable. Before you begin a tea diet, read this guide first to avoid nasty surprises.

When I first started this site, I decided to investigate side effects. I promise myself that I wouldn't make any recommendation without first understanding the risks.

I felt quite stupid at first. After all, even the United States FDA categories tea as "Generally Recognized as Safe". It is the second most consumed beverage after water. What can possibly go wrong?

Tea health benefits are like 1 million times more powerful than its side effects. Observed side effects are few and far between. Discovered health benefits? There are thousands of them.

But there are a few things to be aware of. Sometimes it is better to be safe than sorry.

I have to confess I am not in anyway medically qualified. I tried my best to inform. If you are in doubt, please speak to your medical adviser or post a question at the Tea Side Effects Forum below.

Green Tea Side Effects Alert #1:
When you have too much caffeine.

Tea contains about half the amount of caffeine found in coffee, so moderate consumption of green tea is unlikely to cause problems for the majority of people.

If you are sensitive to caffeine, here are the symptoms to watch out for:

  • restlessness

  • irritability

  • sleeping problems

  • tremor

  • heart palpitations

  • loss of appetite

  • upset stomach

  • nausea

  • frequent urination

  • skin rash

How to deal with tea caffeine? It is like an onion, surrounded by layers of myths. Are you ready to peel and see what is truly inside?

Tea Caffeine

Green Tea Side Effects Alert #2:
When you have a sensitive stomach.

This is very common. Stomach upset is the second most common complaint after caffeine.

A 1984 study concluded that "tea is a potent stimulant of gastric acid, and this can be reduced by adding milk and sugar."

Discover the 10 tips of enjoying a soothing cup of tea without experiencing stomach upset.

Tea and Stomach Gastric Irritation

Green Tea Side Effects Alert #3:
When you are pregnant or are breastfeeding.

green tea side effects

Green tea contains caffeine, catechins and tannic acids. All three substances have been linked to pregnancy risks.

In addition, drinking a large amount may cause neural tube birth defect in babies.

Moderate consumption should be okay. But one should consider avoiding it altogether during early pregnancy.

Green Tea When Pregnant

Green Tea Side Effects Alert #4:
When you suffer from, or is susceptible to, iron deficiency anaemia.

Tea is known as a "negative calories" beverage. Not only does it contain virtually no calories, it also block the absorption of certain nutrients.

One key concern is iron mal absorption. A 2001 study reports that green tea extract reduces the absorption of non-heme iron by 25%.

Amazingly, another 2005 study found that long-term drinkers develop protective mechanism by having heavier parotic glands. The protein rich saliva neutralises the harmful effect of tea tannin.

Tea, Iron Absorption and Anemia

Green Tea Side Effects Alert #5:
When you experience PMS.

This is a hard one to call. There is mixed evidence.

A 2005 study found that green tea reduces the level of estrogens in the body.

It is not clear if this aggravates hot flashes. If hot flashes is a concern to you, please exercise caution with any tea beverage.

However, a 2003 study suggests that green tea, when taken with other herbs, may alleviate post menopausal symptoms.

Tea and Hot Flashes

Green Tea Side Effects Alert #6:
When you have young children.

If you have young kids, it is advisable for them not to drink tea.

This is because tea contains caffeine that may over-stimulate. It also contains tannins that may block nutrients absorption such as protein and fats in children.

Can Children Drink Tea Safely?

For older children, it is advisable for them to avoid energy drinks such as Enviga.

According to my friend Dr. Shen, energy drinks contain chemicals such as phosphoric acid, Ace-k and potassium benzoate. They are especially bad for kids, and even adults.

Potential side effects include weak bones, bad teeth, cancers and allergies.

Green Tea Energy Drinks Dangers!

Green Tea Side Effects Alert #7:
When you suffer from or are susceptible to thiamine deficiency.

Okay, I am stretching it a bit here ...

Tea reduces the absorption of thiamine (Vitamin B).

Thiamine deficiency leads to a condition known as beriberi. Once common to sailors, beriberi is now relatively rare in the Western world except for in alcoholics.

green tea side effectsGreen Tea Side Effects Alert #8:
When you have too many green tea extract tablets.

This is a real risk.

Some people prefer consuming green tea tablets rather than brewing hot tea. That is fine. But it is dangerous to overdose.

How many tablets can you safely consume? There is no clear cut answer, but some guidelines do exist.

Supplement Side Effects

Green Tea Side Effects Alert #9:
When you drink too much.

Drinking too much tea can be dangerous. Especially if the tea is low quality.

A 2005 study raised concerns about instant iced tea.

A middle aged woman was diagnosed with skeletal fluorosis for drinking up to 2 gallons of iced tea daily. Why? Because her green tea contained too much fluoride.

Fluoride in Green Tea - Danger in Lipton Instant Iced Tea!

Want to know which food and beverage may contain too much fluoride? The USDA database, which contains the fluoride content of more than 400 food and beverages, may be just what you need.

Tea and Fluoride - What Does USDA Say?

Green Tea Side Effects Alert #10:
When you have or are prone to forming kidney stones.

This is a hard one to call.

Kidney stones are mineral deposits made up of calcium, uric acid or the amino acid cysteine. At least 3 quarters of kidney stones are composed of calcium combined with phosphate or oxalic acid. Green tea is a concern because it is rich in oxalic acid.

However, contrary to expectations, recent studies suggest that green tea inhibits urinary stone formation and  prevents kidney stones...

Tea and Kidney Stones

Green Tea Side Effects Alert #11:
When you are sensitive to tea.

Green Tea Side Effects

This is another contradicting one ...

Drinking green tea may prevent allergy. But it also contains caffeine and tannin that may cause allergy.

Tea and Allergy

Green Tea Side Effects Alert #12:
Beware of slimming and weight loss teas.

There are many kinds of Chinese slimming and weight loss teas. While green tea is considered safe for long term consumption, slimming and weight loss teas that contain stimulant laxative herbs such as senna leaf and rhubarb root are especially dangerous when consumed in large quantity.

The FDA is on red alert. There have been 4 case reports of young women who died, of which herbal diet tea may be a contributing factor.

Herbal Laxative Tea - Diet Slimming and Constipation Relief?

For an in depth review of tea weight loss properties, visit Weight Loss Tea - How To Be A Successful Loser.

Green Tea Side Effects Alert #13:
When you don't brush your teeth effectively

Drinking tea or coffee stains or discolors the dental plaque, but not the teeth itself.

If the plaque is not completely brushed and flossed away within 24 hours, it begins to harden and becomes what is commonly known as tartar. This tartar is porous and further absorbs stains from other food products.

When a dentist clean your teeth, they remove the tartar and plaque. When the tartar and plaque go away, so do the teeth stains.

Want to find out what's the best ways to prevent teeth stains? Read Tea Staining and Teeth - 5 Whitening and Removal Tips.

Green Tea Side Effects Alert #14:
When you eat lots of tea leaves

The healthiest way to enjoy tea is to brew and drink the liquor. When you drink tea, you are protecting yourself from harmful insoluble solids that may be present in the leaves (such as synthetic pesticide DDT).

Matcha green tea sellers claim that when you consume tea powder, you are maximising its health benefits. This is garbage. Drinking green tea is the safest and most proven way of ingesting green tea antioxidants.

Green Tea Side Effects Alert #15:
When you are on medication or have a medical history.

This is perhaps the most important side effect of which to be aware.

Green tea, like any other tea beverages, can interfere and interact with certain medications. It is wise to avoid drinking any tea beverages 2 hours after taking medications.

Tea and Medical Interaction

Green tea contains caffeine. Caffeine can increase heart rate and blood pressure, although people who consume caffeine regularly don't seem to experience these effects in the long-term.

Caffeine can also increase blood sugar levels. Diabetes patients should drink it cautiously.

The same applies to those with psychological disorders, especially anxiety or panic disorders, and overactive thyroid or hyperthyroidism.

Take care if you have severe liver disease, as the level of caffeine in the blood may build up and last longer.

Finally, if you have any other health concerns, play it safe. Consult with your health adviser before drinking green tea.

New! Comments: Like This Story? Leave A Comment!


Medline Plus: Green Tea (Camellia sinensis).

Also In This Section...

Seven Habits To Minimise Side Effects

How to reap the maximum health benefits of your soothing cup of tea while minimizing its nasty surprises.

Drinking Too Much Tea

Take any healthy food excessively, it is likely to turn into a poison.

Potential Serious Side Effects

There are few case reports documenting serious side effects of tea. Here are worse case scenarios for the truly cautious.

Oolong Tea Side Effects

Like any other tea beverages. They key is to avoid the low quality teas.

7 Things To Avoid When Drinking Tea

What Chinese Medicine says about the art of tea drinking.

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