Health Guide


What is it?

Tea is a drink used to prevent cancer and heart disease. It may also be used to treat type 2 diabetes, tooth cavities, and high cholesterol (ko-LES-ter-all). Tea will be called "medicine" in other parts of this leaflet.

Other names for tea include: Camellia sinensis, Chinese tea, Sencha, Unfermented tea, Oolong tea, or Green tea.

Ask your doctor, nurse, or pharmacist if you need more information about this medicine or if any information in this leaflet concerns you.

Before Using:

Tell your doctor if you

  • are taking medicine or are allergic to any medicine (prescription or over-the-counter (OTC) or dietary supplement)
  • are pregnant or plan to become pregnant while using this medicine
  • are breast feeding
  • have any other health problems, such as high blood pressure or heart or blood vessel disease


Talk with your caregiver about how much tea you should take. The amount depends on the strength of the medicine and the reason you are taking tea. If you are using this medicine without instructions from your caregiver, follow the directions on the medicine bottle. Do not take more tea or take it more often than what is written on the directions.

To store this medicine:

Keep all medicine locked up and away from children. Store medicine away from heat and direct light. Do not store your medicine in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down and not work the way it should work. Throw away medicine that is out of date or that you do not need. Never share your medicine with others.

Drug and Food Interactions:

Do not take tea without talking to your doctor first if you are taking:

  • Alendronate (Fosamax(R))
  • Blood thinning medicine (examples: warfarin (Coumadin(R)))
  • Cimetidine (Tagamet(R))
  • Clozapine (Clozaril(R))
  • Creatine
  • Dipyridamole (Persantine(R))
  • Disulfiram (Antabuse(R))
  • Fluvoxamine (Luvox(R))
  • Hormonal contraceptives (birth control)
  • Lithium (Eskalilth(R), Eskalith CR(R), Lithane(R), Lithoid(R))
  • Ma huang (Maxadrine(R) with ephedra; Ephedra 1000(R))
  • Medicines to help you sleep, relax, or for seizures (alprazolam (Xanax(R)), lorazepam (Ativan(R)), diazepam (Valium(R)))
  • Methoxsalen (8-MOP(R), Oxsoralen(R), Oxsoralen-Ultra(R), Uvadex(R))
  • Mexiletine (Mexitil(R))
  • Norfloxacin (Noroxin(R))
  • Ofloxacin (Floxin(R))
  • Pantoprazole (Pantoloc(R), Protonix(R))
  • Phenylpropanolamine
  • Riluzole (Rilutek(R))
  • St. John's Wort
  • Terbinafine (Lamisil(R))
  • Theophylline (Elixophyllin(R), Slo-Bid(R), Slo-phyllin(R), Theo-24 (R), Theo-dur(R), Theochron(R), Uniphyl(R))
  • Verapamil (Calan SR(R), Covera-HS(R), Isoptin(R), Verelan(R), Verelan PM(R))


  • Before taking tea, tell your doctor if you are pregnant or breast feeding.
  • The use of tea in infants and children should occur only under the advice of a care giver.
  • Mental health problems may occur or worsen if too much tea is used.
  • Caution should be used if tea is used by children with heart, liver, kidney, or seizure (convulsion) problems.

Side Effects:

Stop taking your medicine right away and talk to your doctor if you have any of the following side effects.

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing, or rash.

Other Side Effects:

You may have the following side effects, but this medicine may also cause other side effects. Tell your doctor if you have side effects that you think are caused by this medicine.

  • Increased bleeding.
  • Increased blood pressure.
  • Muscle spasms or twitches.
  • Palpitations (pall-pih-ta-shun). This is a pounding or racing feeling in your heart.
  • Rapid heart beat or an abnormal heart rhythm, which is called an arrhythmia (ah-RITH-me-ah).
  • Restlessness, irritability, nervousness, insomnia (sleeplessness), flushing, or headaches.
  • High or low blood sugar.
  • Stomach problems.
  • Drinking large amounts of caffeine-containing tea may cause a woman problems trying to get pregnant.
  • Drinking large amounts of caffeine-containing tea may cause a woman to have fibrocystic breast disease ("lumpy breasts").
  • Reports of anemia (low blood iron) in children drinking an average of 250 milliliters of green tea/day has been reported. Green tea may change the way iron is used in the body.
  • Bergamot oil, found in Earl Grey tea, may cause liver toxicity and skin problems. It may also cause the skin to be sensitive to the sun.


1 . Dombek C: The Lawrence Review of Natural Products. Wolters Kluwer Company, St. Louis, MO; 1993.

2. Finsterer J: Earl gray tea intoxication. Lancet 2002; 359:1484.

3. Gilman AG, Rall TW, Nies AS et al (eds): Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th ed. Pergamon Press, New York, NY; 1990.

4. Jee SH, He J, Whelton PK et al: The effect of chronic coffee drinking on blood pressure. a meta-analysis of controlled clinical trials. Hypertension 1999; 33:647-652.

5. Merhav H, Amitai Y, Palti H et al: Tea drinking and microcytic anemia in infants. Am J Clin Nutr 1985; 41(6): 1210-1213.

6. Product Information: Cafcit(R), caffeine citrate. Ben Venue Laboratories, Inc, Bedford, OH; 1999.

7. Sheetz DA: Caffeine and chronic back pain (letter). Arch Phys Med Rehabil 1997; 78:786.

8. Somani SM & Gupta P: Caffeine: a new look at an age-old drug. Int J Clin Pharmacol Ther Toxicol 1988; 26: 521-533.

9. Taylor JR & Wilt VM: Probable antagonism of Warfarin by green tea. Ann Pharmacother 1999; 33(4):426-428.

10. Yamamoto T, Juneja LR, Chu DC & Kim M: Chemistry and Applications of green tea. CRC Press, Boca Raton, FL; 1997.

Last Updated: 4/4/2014
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