Black Tea

18/Description

About

Black tea is a product made from the Camellia sinensis plant. The aged leaves and stems are used to make medicine. Green tea, which is made from fresh leaves of the same plant, has some different properties.

Black tea is used for improving mental alertness as well as learning, memory, and information processing skills. It is also used for treating headache; both low and high blood pressure; high cholesterol; preventing heart disease, including "hardening of the arteries" (atherosclerosis) and heart attack; preventing stroke; preventing Parkinson's disease; and reducing the risk of osteoporosis. Black tea is also taken by mouth to prevent cancer, including stomach and intestine cancer, colon and rectal cancer, lung cancer, ovarian cancer, bladder cancer, mouth cancer, pancreatic cancer, prostate cancer, breast cancer, cancer of the kidneys, cancer of the esophagus, and cancer of the lining of the uterus (endometrial cancer). It is also used for type 2 diabetes, stomach disorders, vomiting, diarrhea, and to increase urine flow. Some people use black tea for preventing tooth decay and kidney stones. Black tea is also used to decrease stress. In combination with various other products, black tea is used for weight loss.

In foods, black tea is consumed as a hot or cold beverage.

How it works

Black tea contains 2% to 4% caffeine, which affects thinking and alertness, increases urine output, and may reduce the symptoms of Parkinson's disease. It also contains antioxidants and other substances that might help protect the heart and blood vessels.

Effectiveness

Likely Effective
Mental alertness

Drinking black tea and other caffeinated beverages throughout the day helps to keep people alert and improve attention, even after extended periods without sleep. The effect appears to increase with increasing amount of caffeine in the caffeinated beverages.

Concerns

Likely safe

Drinking moderate amounts of black tea is LIKELY SAFE for most adults

Possibly unsafe

Drinking too much black tea, such as more than five cups per day, is POSSIBLY UNSAFE. High amounts of black tea can cause side effects due to the caffeine in black tea. These side effects can range from mild to serious and include headache, nervousness, sleep problems, vomiting, diarrhea, irritability, irregular heartbeat, tremor, heartburn, dizziness, ringing in the ears, convulsions, and confusion. Also, people who drink black tea or other caffeinated beverages all the time, especially in large amounts, can develop psychological dependence

Likely unsafe

Drinking very high amounts of black tea containing more than 10 grams of caffeine is LIKELY UNSAFE. Doses of black tea this high might cause death or other severe side effects.

18/Warnings

Warnings

Children: Black tea isPOSSIBLY SAFEwhen taken by mouth by children in amounts commonly found in foods.

Pregnancy and breast-feeding: If you are pregnant or breast-feeding, drinking black tea in small amounts is POSSIBLY SAFE. Do not drink more than 2 cups a day of black tea. This amount of tea provides about 200 mg of caffeine. Consuming more than this amount during pregnancy is POSSIBLY UNSAFE and has been linked to an increased risk of miscarriage, increased risk of sudden infant death syndrome (SIDS), and other negative effects, including symptoms of caffeine withdrawal in newborns and lower birth weight.

If you are breast-feeding, drinking more than 3 cups a day of black tea is POSSIBLY UNSAFE and might cause your baby to become more irritable and have more bowel movements.

Anemia: Drinking black tea may make anemia worse in people with iron deficiency.

Anxiety disorders: The caffeine in black tea might make these conditions worse.

Bleeding disorders: There is some reason to believe that the caffeine in black tea might slow blood clotting, though this hasn't been shown in people. Use caffeine cautiously if you have a bleeding disorder.

Heart problems: Caffeine in black tea can cause irregular heartbeat in certain people. If you have a heart condition, use caffeine with caution.

Diabetes: The caffeine in black tea might affect blood sugar. Use black tea with caution if you have diabetes.

Diarrhea: Black tea contains caffeine. The caffeine in black tea, especially when taken in large amounts, can worsen diarrhea.

Seizures: Black tea contains caffeine. There is a concern that high doses of caffeine might cause seizures or decrease the effects of drugs used to prevent seizures. If you have ever had a seizure, don't use high doses of caffeine or caffeine-containing supplements such as black tea.

Glaucoma: Drinking caffeinated black tea increases the pressure inside the eye. The increase occurs within 30 minutes and lasts for at least 90 minutes.

Hormone-sensitive condition such as breast cancer, uterine cancer, ovarian cancer, endometriosis, or uterine fibroids: Black tea might act like estrogen. If you have any condition that might be made worse by exposure to estrogen, don't use black tea.

High blood pressure: The caffeine in black tea might increase blood pressure in people with high blood pressure. However, this doesn't seem to occur in people who regularly drink black tea or other caffeinated products.

Irritable bowel syndrome (IBS): Black tea contains caffeine. The caffeine in black tea, especially when taken in large amounts, can worsen diarrhea and might worsen symptoms of IBS.

Brittle bones (osteoporosis): Drinking caffeinated black tea can increase the amount of calcium that is flushed out in the urine. This might weaken bones. Don't drink more than 300 mg of caffeine per day (approximately 2-3 cups of black tea). Taking extra calcium may help to make up for calcium losses. Older women who have a genetic condition that affects the way they use vitamin D, should use caffeine with caution.

Overactive bladder: The caffeine in black tea might increase the risk of developing an overactive bladder. Also, black tea might increase symptoms in people who already have an overactive bladder. Black tea should be used with caution in these people.

Interactions

Always consult with your doctor.
Moderate
Adenosine (Adenocard)

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

Carbamazepine (Tegretol)

Black tea contains caffeine. 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 black 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).Carbamazepine is a drug used to treat seizures. Caffeine can decrease the effects of carbamazepine. Since black tea contains caffeine, in theory taking black tea with carbamazepine might decrease the effects of carbamazepine and increase the risk of seizures in some people.

Cimetidine (Tagamet)

Black 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 black tea might increase the chance of caffeine side effects including jitteriness, headache, fast heartbeat, and others.

Clozapine (Clozaril)

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

Dipyridamole (Persantine)

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

Disulfiram (Antabuse)

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

Ephedrine

Black tea contains caffeine. Caffeine is a stimulant drug. Stimulant drugs speed up the nervous system. Ephedrine is also a stimulant drug. Taking black 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.

Ethosuximide

Black tea contains caffeine. The body breaks down caffeine to get rid of it. Estrogens can decrease how quickly the body breaks down caffeine. Taking estrogen pills and drinking black 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.Ethosuximide is a drug used to treat seizures. Caffeine in black tea can decrease the effects of ethosuximide. Taking black tea with ethosuximide might decrease the effects of ethosuximide and increase the risk of seizures in some people.

Felbamate

Felbamate is a drug used to treat seizures. Caffeine in black tea might decrease the effects of felbamate. Taking black tea with felbamate might decrease the effects of felbamate and increase the risk of seizures in some people.

Flutamide (Eulexin)

The body breaks down flutamide (Eulexin) to get rid of it. Caffeine in black tea might decrease how quickly the body gets rid of flutamide. This could cause flutamide to stay in the body too long and increase the risk of side effects.

Fluvoxamine (Luvox)

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

Lithium

Your body naturally gets rid of lithium. The caffeine in black 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.

Medications that change the liver (Cytochrome P450 1A2 (CYP1A2) inhibitors)

Black 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).Black tea contains caffeine. Caffeine can stimulate the body. Some medications used for depression can also stimulate the body. Drinking black tea and taking some medications for depression might cause too much stimulation of the body and serious side effects including fast heartbeat, high blood pressure, nervousness, and others.Some of these medications used for depression include phenelzine (Nardil), tranylcypromine (Parnate), and others.Black tea contains caffeine. Caffeine is broken down by the liver. Some medications decrease how well the liver breaks down other medications. These medications that change the liver might decrease how fast caffeine in black tea is broken down in the body. This might increase the effects and side effects of caffeine in black tea. Some medications that change the liver include cimetidine (Tagamet), ciprofloxacin (Cipro), fluvoxamine (Luvox), and others.

Nicotine

Black tea contains caffeine. Caffeine might slow blood clotting. Taking black tea along with medications that also slow clotting might increase the chances of bruising and bleeding.Some medications that slow blood clotting 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.Black tea contains caffeine. Caffeine can stimulate the heart. Nicotine can also stimulate the heart. Taking caffeine with nicotine might cause too much stimulation and cause heart problems, such as increased heart rate or blood pressure.

Pentobarbital (Nembutal)

The stimulant effects of the caffeine in black tea might block the sleep-producing effects of pentobarbital.

Phenobarbital

Phenobarbital is a drug used to treat seizures. Caffeine in black tea might decrease the effects of phenobarbital. Taking black tea with phenobarbital might decrease the effects of phenobarbital and increase the risk of seizures in some people.

Phenylpropanolamine

The caffeine in black tea can stimulate the body. Phenylpropanolamine can also stimulate the body. Taking caffeine and phenylpropanolamine together might cause too much stimulation and increase heartbeat, blood pressure, and cause nervousness.

Phenytoin

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

Riluzole (Rilutek)

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

Stimulant drugs

Stimulant drugs speed up the nervous system. By speeding up the nervous system, stimulant medications can make you feel jittery and speed up your heartbeat. The caffeine in black tea can also speed up the nervous system. Drinking black tea along with stimulant drugs might cause serious problems including increased heart rate and high blood pressure. Avoid taking stimulant drugs along with black tea.Some stimulant drugs include diethylpropion (Tenuate), epinephrine, phentermine (Ionamin), pseudoephedrine (Sudafed), and many others.

Theophylline

Black tea contains caffeine. Caffeine works similarly to theophylline. Caffeine can also decrease how quickly the body gets rid of theophylline. This might cause increased effects and side effects of theophylline.

Valproate

Valproate is a drug used to treat seizures. Caffeine in black tea can decrease the effects of valproate. Taking black tea with valproate might decrease the effects of valproate and increase the risk of seizures in some people.

Verapamil (Calan, Covera, Isoptin, Verelan)

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

Warfarin (Coumadin)

Warfarin (Coumadin) is used to slow blood clotting. Large amounts of black tea might decrease how well warfarin (Coumadin) slows blood clotting. Decreasing how well warfarin (Coumadin) slows blood clotting 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.

Minor
Alcohol

Black tea contains caffeine. Caffeine, especially in excessive amounts, can reduce potassium in the body. "Water pills" can also decrease potassium in the body. Taking caffeine-containing products along with "water pills" might decrease potassium in the body too much.Some "water pills" that can decrease potassium include chlorothiazide (Diuril), chlorthalidone (Thalitone), furosemide (Lasix), hydrochlorothiazide (HCTZ, HydroDIURIL, Microzide), and others.Black tea contains caffeine. The body breaks down the caffeine in black tea to get rid of it. Alcohol can decrease how quickly the body breaks down caffeine. Taking black tea along with alcohol might cause too much caffeine in the bloodstream and caffeine side effects including jitteriness, headache, and fast heartbeat.

Fluconazole (Diflucan)

Black 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. Taking black tea along with birth control pills might 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.Black 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. This could cause caffeine to stay in the body too long and increase the risk of side effects such as nervousness, anxiety, and insomnia.

METFORMIN (Glucophage)

Black tea contains chemicals called tannins. Tannins can bind to many medications, including tricyclic antidepressants, and decrease how much medicine the body absorbs. To avoid this interaction, avoid black tea 1 hour before and 2 hours after taking medications for depression called tricyclic antidepressants.Some medications for depression include amitriptyline (Elavil) or imipramine (Tofranil, Janimine).Black tea contains caffeine. Caffeine might increase blood sugar. Diabetes medications are used to lower blood sugar. By increasing blood sugar, the caffeine in black tea 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.Black tea contains caffeine. The body breaks down caffeine to get rid of it. Metformin (Glucophage) can decrease how quickly the body breaks down caffeine. Taking black tea along with metformin might cause too much caffeine in the body, and increase the effects and side effects of caffeine.

Methoxsalen (Oxsoralen)

Black tea contains caffeine. The body breaks down caffeine to get rid of it. Methoxsalen (Oxsoralen) can decrease how quickly the body breaks down caffeine. Taking caffeine along with methoxsalen might cause too much caffeine in the body, and increase the effects and side effects of caffeine.

Mexiletine (Mexitil)

Black 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 black tea might increase the caffeine effects and side effects of black tea.

Terbinafine (Lamisil)

Black tea contains chemicals called tannins. Tannins can bind to many medications, including phenothiazines, and decrease how much medicine the body absorbs. To avoid this interaction, avoid black tea one hour before and two hours after taking phenothiazine medications.Some phenothiazine medications include fluphenazine (Permitil, Prolixin), chlorpromazine (Thorazine), haloperidol (Haldol), prochlorperazine (Compazine), thioridazine (Mellaril), and trifluoperazine (Stelazine).The body breaks down the caffeine in black tea to get rid of it. Terbinafine (Lamisil) can decrease how quickly the body gets rid of caffeine and increase the risk of side effects including jitteriness, headache, increased heartbeat, and other effects.

Tiagabine

Black tea contains caffeine. Taking caffeine over a long time period along with tiagabine can increase the amount of tiagabine in the body. This might increase the effects and side effects of tiagabine.

Ticlopidine (Ticlid)

The body breaks down the caffeine in black tea to get rid of it. Ticlopidine (Ticlid) can decrease how quickly the body gets rid of caffeine. Taking black tea along with ticlopidine might increase the effects and side effects of caffeine, including jitteriness, hyperactivity, irritability, and others.

The information provided on this page is for reference purposes and is not meant to be used as a medical advice, diagnosis or treatment. Always consult with a medical professional. The content on this page has been provided with thanks by RxList.com