Green Tea

Are there any interactions with medications?

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Amphetamines
Interaction Rating: Major Do not take this combination.

Stimulant drugs such as amphetamines speed up the nervous system. By speeding up the nervous system, stimulant medications can make you feel jittery and increase your heart rate. The caffeine in green tea might also speed up the nervous system. Taking green tea along with stimulant drugs might cause serious problems including increased heart rate and high blood pressure. Avoid taking stimulant drugs along with caffeine.

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Cocaine
Interaction Rating: Major Do not take this combination.

Stimulant drugs such as cocaine speed up the nervous system. By speeding up the nervous system, stimulant medications can make you feel jittery and increase your heart rate. The caffeine in green tea might also speed up the nervous system. Taking green tea along with stimulant drugs might cause serious problems including increased heart rate and high blood pressure. Avoid taking stimulant drugs along with caffeine.

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Ephedrine
Interaction Rating: Major Do not take this combination.

Stimulant drugs speed up the nervous system. Caffeine (contained in green tea) and ephedrine are both stimulant drugs. Taking green tea along with ephedrine might cause too much stimulation and sometimes serious side effects and heart problems. Do not take caffeine-containing products and ephedrine at the same time.

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Adenosine (Adenocard)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Green tea contains caffeine. The caffeine in green tea might block the effects of adenosine (Adenocard). Adenosine (Adenocard) is often used by doctors to do a test on the heart, called a cardiac stress test. Stop consuming green tea or other caffeine-containing products at least 24 hours before a cardiac stress test.

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Antibiotics (Quinolone antibiotics)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

The body breaks down caffeine to get rid of it. Some antibiotics might decrease how quickly the body breaks down caffeine. Taking these antibiotics along with green tea can increase the risk of side effects including jitteriness, headache, increased heart rate, and other side effects.

Some antibiotics that decrease how quickly the body breaks down caffeine include ciprofloxacin (Cipro), enoxacin (Penetrex), norfloxacin (Chibroxin, Noroxin), sparfloxacin (Zagam), trovafloxacin (Trovan), and grepafloxacin (Raxar).

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Birth control pills (Contraceptive drugs)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

The body breaks down the caffeine in green tea to get rid of it. Birth control pills can decrease how quickly the body breaks down caffeine. Taking green tea along with birth control pills can cause jitteriness, headache, fast heartbeat, and other side effects.

Some birth control pills include ethinyl estradiol and levonorgestrel (Triphasil), ethinyl estradiol and norethindrone (Ortho-Novum 1/35, Ortho-Novum 7/7/7), and others.

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Bortezomib (Velcade)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Bortezomib (Velcade) is used in certain types of cancers. Green tea might interact with bortezomib (Velcade) and decrease its effectiveness for treating certain types of cancer. If you take bortezomib (Velcade) avoid taking green tea products.

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Cimetidine (Tagamet)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Green tea contains caffeine. The body breaks down caffeine to get rid of it. Cimetidine (Tagamet) can decrease how quickly your body breaks down caffeine. Taking cimetidine (Tagamet) along with green tea might increase the chance of caffeine side effects including jitteriness, headache, fast heartbeat, and others.

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Clozapine (Clozaril)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

The body breaks down clozapine (Clozaril) to get rid of it. The caffeine in green tea seems to decrease how quickly the body breaks down clozapine (Clozaril). Taking green tea along with clozapine (Clozaril) can increase the effects and side effects of clozapine (Clozaril).

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Dipyridamole (Persantine)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Green tea contains caffeine. The caffeine in green tea might block the affects of dipyridamole (Persantine). Dipyridamole (Persantine) is often used by doctors to do a test on the heart called a cardiac stress test. Stop drinking green tea or other caffeine-containing products at least 24 hours before a cardiac stress test.

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Disulfiram (Antabuse)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

The body breaks down caffeine to get rid of it. Disulfiram (Antabuse) can decrease how quickly the body gets rid of caffeine. Taking green tea (which contains caffeine) along with disulfiram (Antabuse) might increase the effects and side effects of caffeine, including jitteriness, hyperactivity, irritability, and others.

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Estrogens
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

The body breaks down the caffeine in green tea to get rid of it. Estrogens can decrease how quickly the body breaks down caffeine. Taking estrogen pills and drinking green tea can cause jitteriness, headache, fast heartbeat, and other side effects. If you take estrogen pills, limit your caffeine intake.

Some estrogen pills include conjugated equine estrogens (Premarin), ethinyl estradiol, estradiol, and others.

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Fluvoxamine (Luvox)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

The body breaks down the caffeine in green tea to get rid of it. Fluvoxamine (Luvox) can decrease how quickly the body breaks down caffeine. Taking green tea along with fluvoxamine (Luvox) might cause too much caffeine in the body, and increase the effects and side effects of caffeine.

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Lithium
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Your body naturally gets rid of lithium. The caffeine in green tea can increase how quickly your body gets rid of lithium. If you take products that contain caffeine and you take lithium, stop taking caffeine products slowly. Stopping caffeine too quickly can increase the side effects of lithium.

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Medications for asthma (Beta-adrenergic agonists)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Green tea contains caffeine. Caffeine can stimulate the heart. Some medications for asthma can also stimulate the heart. Taking caffeine with some medications for asthma might cause too much stimulation and cause heart problems.

Some medications for asthma include albuterol (Proventil, Ventolin, Volmax), metaproterenol (Alupent), terbutaline (Bricanyl, Brethine), and isoproterenol (Isuprel).

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Medications that can harm the liver (Hepatotoxic drugs)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Green tea extracts might harm the liver. Taking green tea extracts along with medication that might also harm the liver can increase the risk of liver damage. Do not take green tea extracts if you are taking a medication that can harm the liver.

Some medications that can harm the liver include acetaminophen (Tylenol and others), amiodarone (Cordarone), carbamazepine (Tegretol), isoniazid (INH), methotrexate (Rheumatrex), methyldopa (Aldomet), fluconazole (Diflucan), itraconazole (Sporanox), erythromycin (Erythrocin, Ilosone, others), phenytoin (Dilantin) , lovastatin (Mevacor), pravastatin (Pravachol), simvastatin (Zocor), and many others.

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Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Green tea might slow blood clotting. Taking green tea along with medications that also slow clotting might increase the chances of bruising and bleeding.

Some medications that slow blood clotting include ardeparin (Normiflo), aspirin, clopidogrel (Plavix), diclofenac (Voltaren, Cataflam, others), dipyridamole (Persantine), ibuprofen (Advil, Motrin, others), naproxen (Anaprox, Naprosyn, others), dalteparin (Fragmin), enoxaparin (Lovenox), heparin, ticlopidine (Ticlid), warfarin (Coumadin), and others.

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Medications used to treat cancer (Boronic acid-based proteasome inhibitors)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Green tea might interact with some medications used to treat cancer (boronic acid-based proteasome inhibitors). This might decrease its effectiveness of these medications for treating certain types of cancer. If you take one of these medications for cancer, avoid taking green tea products. Some of these drugs include bortezomib (Velcade).

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Nicotine
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Stimulant drugs such as nicotine speed up the nervous system. By speeding up the nervous system, stimulant medications can make you feel jittery and increase your heart rate. The caffeine in green tea might also speed up the nervous system. Taking green tea along with stimulant drugs might cause serious problems, including increased heart rate and high blood pressure. Avoid taking stimulant drugs along with caffeine.

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Pentobarbital (Nembutal)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

The stimulant effects of the caffeine in green tea can block the sleep-producing effects of pentobarbital (Nembutal).

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Phenylpropanolamine
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Green tea contains caffeine. Caffeine can stimulate the body. Phenylpropanolamine can also stimulate the body. Taking green tea and phenylpropanolamine together might cause too much stimulation and increase heartbeat, increase blood pressure, and cause nervousness.

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Riluzole (Rilutek)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

The body breaks down riluzole (Rilutek) to get rid of it. Drinking green tea can decrease how quickly the body breaks down riluzole (Rilutek) and increase the effects and side effects of riluzole.

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Theophylline
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Green tea contains caffeine. Caffeine works similarly to theophylline. Caffeine can also decrease how quickly the body gets rid of theophylline. Taking green tea along with theophylline might increase the effects and side effects of theophylline.

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Verapamil (Calan, Covera, Isoptin, Verelan)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

The body breaks down the caffeine in green tea to get rid of it. Verapamil (Calan, Covera, Isoptin, Verelan) can decrease how quickly the body gets rid of caffeine. Drinking green tea and taking verapamil (Calan, Covera, Isoptin, Verelan) can increase the risk of side effects for caffeine including jitteriness, headache, and an increased heartbeat.

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Warfarin (Coumadin)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Warfarin (Coumadin) is used to slow blood clotting. Large amounts of green tea have been reported to decrease the effectiveness of warfarin (Coumadin). Decreasing the effectiveness of warfarin (Coumadin) might increase the risk of clotting. It is unclear why this interaction might occur. Be sure to have your blood checked regularly. The dose of your warfarin (Coumadin) might need to be changed.

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Alcohol
Interaction Rating: Minor Be cautious with this combination.
Talk with your health provider.

The body breaks down the caffeine in green tea to get rid of it. Alcohol can decrease how quickly the body breaks down caffeine. Taking green tea along with alcohol might cause too much caffeine in the bloodstream and caffeine side effects including jitteriness, headache, and fast heartbeat.

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Fluconazole (Diflucan)
Interaction Rating: Minor Be cautious with this combination.
Talk with your health provider.

Green tea contains caffeine. The body breaks down caffeine to get rid of it. Fluconazole (Diflucan) might decrease how quickly the body gets rid of caffeine and cause caffeine to stay in the body too long. Taking fluconazole (Diflucan) along with green tea might increase the risk of side effects such as nervousness, anxiety, and insomnia.

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Medications for diabetes (Antidiabetes drugs)
Interaction Rating: Minor Be cautious with this combination.
Talk with your health provider.

Green tea contains caffeine. There is conflicting evidence that caffeine might either increase or decrease blood sugar. Diabetes medications are used to lower blood sugar. Taking some medications for diabetes along with caffeine might decrease the effectiveness of diabetes medications. Monitor your blood sugar closely. The dose of your diabetes medication might need to be changed.

Some medications used for diabetes include glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, Micronase), insulin, pioglitazone (Actos), rosiglitazone (Avandia), chlorpropamide (Diabinese), glipizide (Glucotrol), tolbutamide (Orinase), and others.

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Mexiletine (Mexitil)
Interaction Rating: Minor Be cautious with this combination.
Talk with your health provider.

Green tea contains caffeine. The body breaks down caffeine to get rid of it. Mexiletine (Mexitil) can decrease how quickly the body breaks down caffeine. Taking Mexiletine (Mexitil) along with green tea might increase the caffeine effects and side effects of green tea.

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Terbinafine (Lamisil)
Interaction Rating: Minor Be cautious with this combination.
Talk with your health provider.

The body breaks down the caffeine in green tea to get rid of it. Terbinafine (Lamisil) can decrease how fast the body gets rid of caffeine. Taking green tea along with terbinafine (Lamisil) can increase the risk of caffeine side effects including jitteriness, headache, increased heartbeat, and other effects.

Dosing considerations for Green Tea.

The following doses have been studied in scientific research:

AS A DRINK:
Doses of green tea vary significantly, but usually range between 1-10 cups daily. The commonly used dose of green tea is based on the amount typically consumed in Asian countries, which is about 3 cups per day, providing 240-320 mg of the active ingredients, polyphenols. To make tea, people typically use 1 teaspoon of tea leaves in 8 ounces boiling water.

• For headache or restoring mental alertness: tea providing is up to 250 mg of caffeine per day, or approximately 3 cups of tea per day.
• For improving thinking: tea providing 60 mg of caffeine, or approximately one cup.
• For reducing cholesterol: drinking 10 or more cups per day has been associated with decreased cholesterol levels. Theaflavin-enriched green tea extract, 375 mg daily for 12 weeks, has also been used for lowering cholesterol.
• For human papilloma virus (HPV) infections of the cervix: green tea extract, 200 mg daily alone or in combination with topical green tea ointment, for 8-12 weeks.
• For preventing Parkinson's disease:
• Men consuming 421-2716 mg total caffeine (approximately 5-33 cups of green tea) daily have the lowest risk of developing Parkinson's disease. However, a significantly lower risk is also associated with consumption of as little as 124-208 mg of caffeine (approximately 1-3 cups of green tea) daily.
• In women: more moderate caffeine consumption seems to be best, equivalent to approximately 1-4 cups of green tea per day.

APPLIED TO THE SKIN:

• For human papillomavirus (HPV) infections of the cervix: green tea ointment alone or in combination with oral green tea extract, twice weekly for 8-12 weeks.
• For genital warts: a specific green tea extract ointment (Veregen, Bradley Pharmaceuticals) providing 15% kunecatechins applied three times daily to external warts for up to 16 weeks has been used.