Adenosine

• Adenocard

Green tea contains caffeine. The caffeine in green tea might block the effects of adenosine, which is often used by doctors to do a test called a cardiac stress test. Stop consuming green tea at least 24 hours before a cardiac stress test.

Antibiotics

• Doxycycline

• Ciprofloxacin

• Amoxicillin

• Azithromycin

• Norfloxacin

• Trimethoprim

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.

Birth control pills

Green tea contains caffeine. The body breaks down caffeine to get rid of it. Birth control pills can decrease how quickly the body breaks down caffeine. This might increase the risk for side effects from caffeine, such as jitteriness, headache, and fast heartbeat.

Bortezomib

• Velcade

Bortezomib is used in certain types of cancers. Green tea might interact with bortezomib and decrease its effects. If you take bortezomib, avoid taking green tea products.

Carbamazepine

Caffeine can decrease the effects of carbamazepine. Since green tea contains caffeine, taking green tea with carbamazepine might decrease the effects of carbamazepine.

Celiprolol

• Celicard

Green tea appears to decrease how much celiprolol is absorbed into the body. This might decrease the effects of celiprolol.

Cimetidine

• Tagamet

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

Clozapine

• Clozaril

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

Dipyridamole

• Persantine

Green tea contains caffeine. The caffeine in green tea might block the effects of dipyridamole. Dipyridamole is often used by doctors to do a test on the heart called a cardiac stress test. Stop drinking green tea at least 24 hours before a cardiac stress test.

Disulfiram

• Antabuse

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

Estrogens

• Oral contraceptive pill

• Estradiol

• Conjugated estrogens

• HRT combination products

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 and drinking green tea can increase the risk of caffeine side effects, including jitteriness, headache, fast heartbeat, and others.

Ethosuximide

• Zarontin

Ethosuximide is a drug used to treat seizures. Caffeine in green tea can decrease the effects of ethosuximide. Taking green tea with ethosuximide might decrease the effects of ethosuximide. This might increase the risk of seizures.

Felbamate

• Felbatol

Felbamate is a drug used to treat seizures. The caffeine in green tea might decrease the effects of felbamate and increase the risk of seizures in some people.

Fexofenadine

• Allegra

Green tea might decrease how much fexofenadine the body absorbs. Separate taking this medication from consuming green tea.

Flutamide

• Eulexin

The body breaks down flutamide to get rid of it. The caffeine in green tea might decrease how quickly the body gets rid of flutamide. This could increase the effects and side effects of flutamide.

Fluvoxamine

• Luvox

The body breaks down the caffeine in green tea to get rid of it. Fluvoxamine can decrease how quickly the body breaks down caffeine. Taking fluvoxamine along with green tea might increase the risk of caffeine side effects such as jitteriness, headache, fast heartbeat, and others.

Imatinib

• Gleevec

Imatinib is used to treat certain types of cancer. Green tea appears to reduce how much imatinib gets into the body. This might decrease the effects of imatinib.

Lisinopril

Green tea appears to decrease how much lisinopril is absorbed into the body. This might decrease the effects of lisinopril.

The caffeine in green tea can increase how quickly the body gets rid of lithium. If you take products that contain caffeine and you take lithium, don't stop taking caffeine all at once. Decrease the daily dose of caffeine slowly. Stopping caffeine too quickly can increase the side effects of lithium.

Medications for asthma

• Beta-adrenergic agonists

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.

Medications for depression

• MAOIs

Green tea contains caffeine. There is some concern that caffeine can interact with certain medications, called MAOIs. If caffeine is taken with these medications, it might increase the risk for serious side effects including fast heartbeat and very high blood pressure. Some common MAOIs include phenelzine, selegiline, and tranylcypromine.

Medications moved by pumps in cells

• Rosuvastatin

• Atorvastatin

• Simvastatin

• Methotrexate

• Fexofenadine

• Levothyroxine

Some medications are moved in and out of cells by pumps. Green tea might change how these pumps work and change how much medication stays in the body. In some cases, this might change the effects and side effects of a medication.

• Dabigatran

• Cyclosporine

• Fexofenadine

• Loperamide

• Some HIV antiretrovirals

Medications that can harm the liver

• Acetaminophen / Paracetamol

• Methotrexate

• Atorvastatin

• Simvastatin

• Isoniazid

Green tea extracts might harm the liver. Some medications can also harm the liver. Taking green tea extracts along with a medication that can harm the liver might increase the risk of liver damage.

Medications that slow blood clotting

• Heparin

• Rivaroxaban

• Apixaban

• Dabigatran

• Clopidogrel

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

Nicotine

Stimulant drugs such as nicotine speed up the nervous system. 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.

Nintedanib

• Ofev

Green tea might decrease how much nintedanib is in the body. It's not clear if this is a real concern.

Pentobarbital

• Nembutal

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

Phenobarbital

• Luminal

Phenobarbital is a drug used to treat seizures. The caffeine in green tea might decrease the effects of phenobarbital and increase the risk of seizures in some people.

Phenylpropanolamine

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 and blood pressure and cause nervousness.

Phenytoin

Phenytoin is a drug used to treat seizures. The caffeine in green tea can decrease the effects of phenytoin. Taking green tea with phenytoin might decrease the effects of phenytoin and increase the risk of seizures in some people.

Pioglitazone

• Actos

Green tea contains caffeine. Caffeine might increase the amount of pioglitazone that the body absorbs. Taking green tea might increase the effects and adverse effects of pioglitazone.

Riluzole

• Rilutek

Drinking green tea can decrease how quickly the body breaks down riluzole and increase the effects and side effects of riluzole.

Rosuvastatin

Taking green tea extract might change the amount of rosuvastatin in the blood. This might change the effects and side effects of rosuvastatin.

Stimulant drugs

Stimulants, such as amphetamines and cocaine, speed up the nervous system. By speeding up the nervous system, stimulant medications can increase blood pressure and speed up the heartbeat. Green tea contains caffeine. Caffeine can 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.

Theophylline

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.

The caffeine in green tea might decrease the effects of valproate.

Verapamil

• Calan, others

Verapamil can decrease how quickly the body gets rid of caffeine. Drinking green tea and taking verapamil can increase the risk of caffeine side effects including jitteriness, headache, and an increased heartbeat.

• Jantoven

• Used for: blood thinning, clot prevention

Green tea contains vitamin K. Vitamin K can reduce the effect of warfarin. But the amount of vitamin K in green tea is very small. So green tea is unlikely to interact with warfarin when used in moderation. Large amounts of green tea, such as 8 cups or more each day, should be avoided.

Diuretics

• Diuretic drugs

Green tea contains caffeine. Caffeine, especially in large amounts, can reduce potassium levels in the body. "Diuretics" can also decrease potassium in the body. Taking large amounts of caffeine along with "Diuretics" might decrease potassium in the body too much.

Aluminum

Aluminum is found in most antacids. Vitamin C can increase how much aluminum the body absorbs. However, it is not clear if this interaction is a big concern. Take vitamin C two hours before or four hours after antacids.

Vitamin C might decrease how quickly the body gets rid of estrogens. Taking vitamin C along with estrogens might increase the effects and side effects of estrogens.

Fluphenazine

• Prolixin

Large amounts of vitamin C might decrease how much fluphenazine is in the body. Taking vitamin C along with fluphenazine might decrease the effectiveness of fluphenazine.

Indinavir

• Crixivan

Taking large amounts of vitamin C along with indinavir might decrease how much indinavir stays in the body. It's not clear if this interaction is a big concern.

Levothyroxine

• Synthroid, others

Taking vitamin C along with levothyroxine might increase how much levothyroxine the body absorbs. This can increase the amount of levothyroxine in the body and increase its effects and side effects.

Medications for cancer

• Cyclophosphamide

• Chlorambucil

• Melphalan

• Busulfan

• Temozolomide

Vitamin C is an antioxidant. There is some concern that antioxidants might decrease the effects of some medications used for cancer. If you are taking medications for cancer, check with your healthcare provider before taking vitamin C.

• Doxorubicin

• Bleomycin

• Daunorubicin

• Mitomycin

• Epirubicin

Vitamin C is an antioxidant. There is some concern that antioxidants might decrease the effects of medications used for cancer. If you are taking medications for cancer, check with your healthcare provider before taking vitamin C.

Niacin

Taking niacin with vitamin C and other antioxidants can decrease the effects of niacin on good cholesterol levels. It is unknown if vitamin C alone decreases the effects of niacin on good cholesterol levels.

Warfarin is used to slow blood clotting. Large amounts of vitamin C might decrease the effects of warfarin. Decreasing the effects of warfarin might increase the risk of clotting. Be sure to have your blood checked regularly. The dose of your warfarin might need to be changed.

Cyclosporine

• Restasis

• Used for: organ transplant, autoimmune conditions

Taking large amounts of vitamin E along with cyclosporine might increase how much cyclosporine the body absorbs. This might increase the effects and side effects of cyclosporine.

Medications changed by the liver

• Atorvastatin

• Simvastatin

• Amlodipine

• Diltiazem

• Cyclosporine

• Tacrolimus

• Midazolam

• Alprazolam

• Rivaroxaban

• Some HIV antiretrovirals

Some medications are changed and broken down by the liver. Vitamin E might change how quickly the liver breaks down these medications. If you are taking medications metabolised by the liver, monitor for any changes in how your medication affects you.

Vitamin E is an antioxidant. There is some concern that antioxidants might decrease the effects of some medications used for cancer. If you are taking medications for cancer, check with your healthcare provider before taking vitamin E.

Vitamin E might slow blood clotting. Taking vitamin E along with medications that also slow blood clotting might increase the risk of bruising and bleeding.

Taking niacin along with the drug simvastatin can increase good cholesterol levels. Taking niacin plus simvastatin along with vitamin E and other antioxidants can decrease the effects of niacin and simvastatin on good cholesterol levels. It is unknown if vitamin E alone decreases the effects of niacin plus simvastatin on good cholesterol levels.

Selumetinib

• Koselugo

Selumetinib, a drug used for cancer, contains vitamin E. Taking selumetinib with vitamin E-containing supplements can result in an unsafe dose of vitamin E. This could increase the risk of bleeding.

Warfarin is used to slow blood clotting. Vitamin E can also slow blood clotting. Taking vitamin E along with warfarin can increase the chances of bruising and bleeding. Be sure to have your blood checked regularly. The dose of your warfarin might need to be changed.

Ledipasvir

Taking milk thistle might decrease how quickly the body breaks down ledipasvir. This might increase the effects and side effects of ledipasvir.

• Cytochrome P450 2B6 substrates

Some medications are changed and broken down by the liver. Milk thistle might change how quickly the liver breaks down these medications. If you are taking medications metabolised by the liver, monitor for any changes in how your medication affects you.

Medications changed by the liver

• Glucuronidated drugs

Medications for diabetes

• Glyburide

• Glipizide

• Insulin

• Sitagliptin

• Empagliflozin

• Semaglutide

• Dapagliflozin

Milk thistle might lower blood sugar levels. Taking milk thistle along with diabetes medications might cause blood sugar to drop too low. Monitor your blood sugar closely.

• P-glycoprotein substrates

Some medications are moved in and out of cells by pumps. Milk thistle might change how these pumps work and change how much medication stays in the body. In some cases, this might change the effects and side effects of a medication.

Milk thistle might affect levels of morphine in the blood. This might increase or decrease the effects and side effects of morphine.

Raloxifene

• Evista

Taking milk thistle might decrease how well the body breaks down raloxifene in the stomach. This might increase the effects and side effects of raloxifene.

Sirolimus

• Rapamune

Taking milk thistle might decrease how well the liver breaks down sirolimus. This might increase the effects and side effects of sirolimus.

Sofosbuvir

Taking milk thistle might increase how quickly the body breaks down sofosbuvir. This might decrease the effects of sofosbuvir.

Tamoxifen

• Soltamox

• Used for: breast cancer treatment and prevention

Milk thistle might increase how much tamoxifen is absorbed by the body. This might increase the effects and side effects of tamoxifen.

Warfarin is used to slow blood clotting. Taking milk thistle might increase the effects of warfarin, which could increase the risk of bleeding.

• Caffeine

• Clozapine

• Olanzapine

• Theophylline

• Tizanidine

• Duloxetine

• Ramelteon

Some medications are changed and broken down by the liver. Grape might change how quickly the liver breaks down these medications. If you are taking medications metabolised by the liver, monitor for any changes in how your medication affects you.

• Tramadol

• Metoprolol

• Fluoxetine

• Paroxetine

• Tamoxifen

• Amitriptyline

Medications changed by the liver

• Cytochrome P450 2E1 substrates

Grape extract might slow blood clotting. Taking grape extract along with medications that also slow blood clotting might increase the risk of bruising and bleeding.

Midazolam

• Versed

Taking grape seed extract for at least one week might increase how quickly the body gets rid of midazolam. This might decrease the effects of midazolam. But taking only a single dose of grape seed extract doesn't seem to have an effect on midazolam.

Phenacetin

Drinking grape juice might increase how quickly the body breaks down phenacetin. Taking phenacetin along with grape juice might decrease the effects of phenacetin.