The Possible Interactions of Green Tea and Some Medications

Photo source: Flickr.

It is known the health benefits of green tea around the world. Otherwise, this beverage can interact with some following medications. If you are treating with any of them, you should not to take any of the green tea products, including tea or any extracts, without talking to your doctor.

Do not take this combination

Amphetamine, Cocaine and Ephedrine interactions with green tea can have serious problems including increased heart rate, high blood pressure, and other side effects.

Use in Moderation

Adenosine (Adenocard)

This medication is given in the hospital for irregular heart rhythm or as test on the heart, called cardiac stress test. The green tea can reduce the actions of it. Stop using green tea or other caffeine contained products at least 24 hours before having a cardiac stress test.

Beta-lactam antibiotics

The green tea can make the bacteria less resistant to treatment and decrease the effect of beta-lactam antibiotics.

Benzodiazepines

Caffeine may reduce the sedative effects of benzodiazepines treatments, using to treat anxiety, such as diazepam (Valium) and lorazepan (Ativan).

Beta-blockers, Propranolol, and Metoprolol

Caffeine may increase blood pressure in people taking propranolol (Inderal), and metoprolol (Toprol XL, Lopressor), using to treat high blood pressure and heart disease.

Blood Thinning Medications (Anticoagulant/Antiplatelet drugs)

The green tea contains vitamin K that can make these treatments ineffective. They both prevent blood from clotting and, using together, may increase risk of bleeding. These treatments include:

aspirin
clopidogrel (Plavix)
diclofenac (Voltaren, Cataflam, others)
ibuprofen (Advil, Motrin, others)
naproxen (Anaprox, Naprosyn, others)
dalteparin (Fragmin)
enoxaparin (Lovenox)
heparin
warfarin (Coumadin)
and others

Birth control pills (Contraceptive drugs)

The oral contraceptives can extend the time caffeine stays in the body. That may increase stimulating process and cause headache, jitteriness, fast heartbeat and other side effects.

Cimetidine (Tagamet)

Taking cimetidine treatment with green tea may increase the caffeine side effects, such as headache, fast heartbur, jitteriness, ant others.

Chemotherapy

The laboratory tests have shown that the chemotherapy medications, specifically doxorubicin and tamoxifen, combined with green tea may increase the effect of these medications. On the other hand, the same results have not been found on people. However, some reports have shown that the green and black tea extracts affect a gene in prostate cancer cells and may make them less sensitive to chemotherapy drugs. For that reason, it is needed to talk to doctor before drinking tea while undergoing chemotherapy.

Clozapine (Clozaril)

The effects of this medication may be reduced if you took it within 40 minutes after drinking green tea.

Dipyridamole (Persantine)

This medication is often used by doctors to do a test on the heart, called a cardiac stress test. Consuming the caffeine contained products might block the affects of it. Stop using caffeine contained products at least 24 hours before a cardiac stress test.

Disulfiram (Antabuse)

Taking the caffeine green tea with disulfiram may increase the side effects such as jitteriness, hyperactivity, irritability, and others.

Estrogens

Drinking green tea and taking estrogen pills may cause headache, fast heartburn, jitteriness, and other side effects. If you are taking these pills, limit your caffeine dose.

Ephedrine

This tea may be reason for agitation, tremors, insomnia, and weight loss while taken with ephedrine.

Hepatotoxic drugs (medications that can harm liver)

The green tea extract can harm liver. Taking it with medications that may also harm liver can increase the risk of liver damage. Do not mix the green tea and hepatotoxic drugs. These medications 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.

Lithium

Green tea may reduce blood levels of lithium, using to treat bipolar disorder. This tea may make lithium less effective. If you use caffeine products and start to take lithium, stop taking caffeine products slowly. Stopping to quickly may has the side effects of lithium.

Monoamine oxidase inhibitors (MAOIs)

These drugs are using to treat depression and include isocarboxazid (Marplan), moclobemide (Manerix), phenelzine (Nardil), tranylcypromine (Parnate), and others. When taken together with these medications, the green tea can cause too much stimulating of the body and a severe increase in blood pressure, called ‘hypertensive crisis’.

Riluzole (Rilutek)

Drinking green tea might decrease the effect of riluzole and increase the side effects.

Phenylpropanolamine

This medication is used in many over-the-counter and prescription cold and cough drugs and weight loss products. The combination of caffeine and these medications may cause mania and severe increase in blood pressure. However, after FDA had urged all manufacturers of this drug to remove this medication from the market, most drugs are reformulated without it. So read the labels.

Pentobarbital (Nembutal)

The stimulant effects of the caffeine may block the sleep-producing effects of this medication.

Stimulating drugs (Nicotine)

These drugs speed up the nervous system, same the caffeine in green tea does. The interaction of these both may cause serious problems, such as increased heart rate and high blood pressure. Avoid having the stimulant drugs and caffeine products together.

Quinolone antibiotics

The green tea may increase effectiveness in these medications and also increase side effects, including jitteriness, headache, increased heart rate, and others, while using these medications, including:

Ciprofloxacin (Cipro)
Enoxacin (Penetrex)
Grepafloxacin (Raxar)
Norfloxacin (Chibroxin, Noroxin)
Sparfloxacin (Zagam)
Trovafloxacin (Trovan)

Other medications

Green tea, especially caffeinated, may interact with many medications, including:

Acetaminophen (Tylenol)
Carbamazepine (Tegretol)
Dipyridamole (Persatine)
Estrogen
Fluvoxamine (Luvox)
Methotrexate
Mexiletine (Mexitil)
Phenobarbital
Theophylline
Verapamil (Bosoptin, Calan, Covera- HS, Verelan, Verelan PM)

The minor interaction can be using green tea with:

Alcohol
Fluconazole (diflucan)
Medications for diabetes
Mexiletine (Mexitil)
Terbinafine (Lamisil)

If you take any medications while drinking or taking green tea products, check if they don’t interact between each other or talk to your health care provider.

Source: The University of Maryland Medical Center and WebMD