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Green tea

Generic Name: green tea (GREEN TEE)
Brand Name:

Medically reviewed on August 3, 2017

What is green tea?

Green tea is a product made from the Camellia sinesis plant and it is also known as Camellia theifera, Constituant Polyphénolique de Thé Vert, CPTV, EGCG, Epigallo Catechin Gallate, Extrait de Camellia Sinensis, Extrait de Thé Vert, Extrait de Thea Sinensis, Green Sencha, Green Tea Extract, Green Tea Polyphenolic Fraction, GTP, GTPF, Japanese Tea, Kunecatechins, Poly E, Polyphenon E, PTV, Té Verde, Tea, Tea Extract, Tea Green, Thé de Camillia, Thé Japonais, Thé Vert, Thé Vert Sensha, Thea bohea, Thea sinensis, Thea viridis, Yame Green Tea, Yame Tea, and other names.

Green tea has been used in alternative medicine as a likely effective aid in treating genital warts, high cholesterol, and maintaining mental alertness.

Green tea has been used in alternative medicine as a possibly effective aid in treating clogged arteries, endometrial and ovarian cancer, low blood pressure, osteoporosis, changes in cervical cells due to human papiloma virus (HPV), white patches in the gums and the prevention of Parkinson's disease.

Other uses not proven with research have included various cancers (bladder, esophagus, pancreas, breast, colon, stomach, leukemia, mouth, prostate, lung); acne, heart disease, diabetes, infertility, high blood presure, obesity, respiratory infections, improvement of athletic perfomrance, wrinkles and others.

It is not certain whether green tea is effective in treating any medical condition. Medicinal use of this product has not been approved by the FDA. Green tea should not be used in place of medication prescribed for you by your doctor.

Green tea is often sold as an herbal supplement. There are no regulated manufacturing standards in place for many herbal compounds and some marketed supplements have been found to be contaminated with toxic metals or other drugs. Herbal/health supplements should be purchased from a reliable source to minimize the risk of contamination.

Green tea may also be used for purposes not listed in this product guide.

Important Information

Follow all directions on the product label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

Before taking this medicine

Before using green tea, talk to your healthcare provider. You may not be able to use green tea if you have certain medical conditions.

Ask a doctor, pharmacist, or other healthcare provider if it is safe for you to use this product if you have:

Green tea is considered possibly safe to use during pregnancy in moderate amounts (2 cups/day).

Caffeine in green tea passes into breast milk and can affect a nursing baby. Do not drink excessive green tea if you are breast-feeding a baby.

Green tea is possibly safe in children in low amounts (caffeine levels found in foods).

How should I take green tea?

When considering the use of herbal supplements, seek the advice of your doctor. You may also consider consulting a practitioner who is trained in the use of herbal/health supplements.

If you choose to use green tea, use it as directed on the package or as directed by your doctor, pharmacist, or other healthcare provider. Do not use more of this product than is recommended on the label.

Do not use different formulations of green tea (such as tablets, extracts, and others) at the same time, unless specifically directed to do so by a health care professional. Using different formulations together increases the risk of an overdose.

Call your doctor if the condition you are treating with green tea does not improve, or if it gets worse while using this product.

If you need a cardiac stress test you should stop taking green tea at least 24 hours before your test.

Store at room temperature away from moisture and heat.

What happens if I miss a dose?

Skip the missed dose if it is almost time for your next scheduled dose. Do not use extra green tea to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. Drinking green tea in very high amounts can cause headache, nervousness, sleep problems, vomit, diarrhea, irregular heartbeats, dizziness, and convulsions and can be dangerous and even fatal.

What should I avoid while taking green tea?

Follow your healthcare provider's instructions about any restrictions on food, beverages, or activity.

Avoid using green tea together with other herbal/health supplements that can also affect blood-clotting. This includes angelica (dong quai), capsicum, clove, danshen, garlic, ginger, ginkgo, horse chestnut, panax ginseng, poplar, red clover, saw palmetto, turmeric, and willow.

Drinking alcohol with this product can cause side effects including jitteriness, headache and fast heartbeat.

Avoid using stimulant drugs such as cocaine or amphetamines when using this product.

Green tea side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Although not all side effects are known, green tea is thought to be likely safe for most people when taken in moderate amounts by mouth or used on the skin.

Stop using green tea and call your healthcare provider at once if you have:

  • an unusual bleeding or any bleeding that will not stop.

Common side effects may include:

Green tea has been reported to cause liver problems in rare cases.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect green tea?

Other drugs may interact with green tea, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.

Do not take green tea without medical advice if you are using any of the following medications:

This list is not complete. Other drugs may interact with green tea, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this product guide.

Further information

  • Consult with a licensed healthcare professional before using any herbal/health supplement. Whether you are treated by a medical doctor or a practitioner trained in the use of natural medicines/supplements, make sure all your healthcare providers know about all of your medical conditions and treatments.

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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