Black Tea

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What other names is Black Tea known by?

Black Leaf Tea, Camellia sinensis, Camellia thea, Camellia theifera, Chinese Tea, English Tea, Feuille de Thé Noir, Té Negro, Tea, Thé Anglais, Thé Noir, Thea bohea, Thea sinensis, Thea viridis, Theaflavin, Théaflavine.

What is Black Tea?

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.

Likely Effective for...

  • 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.

Possibly Effective for...

  • Low blood pressure after eating (postprandial hypotension. Black tea contains caffeine. Drinking beverages containing caffeine helps increase blood pressure in older people who have low blood pressure after eating.
  • Heart attacks. Some research shows that people who drink black tea have a lower risk of having a heart attack. Also, people who have been drinking black tea for at least a year before having a heart attack seem to be less likely to die after having a heart attack.
  • Brittle bones (osteoporosis). Early research suggests that older women who drink more black tea have stronger bones than those who drink less. Drinking more black tea also seems to be linked with a lower risk of hip fracture in older men and women.
  • Ovarian cancer. Women who regularly drink tea, including black tea or green tea, appear to have a lower risk of developing ovarian cancer compared to women who never or rarely drink tea.
  • Parkinson's disease. Some research shows that people who drink caffeinated beverages such as coffee, tea, and cola have a lower risk of Parkinson's disease. The lower risk seems to be directly related to the dose of caffeine in men but not women. Drinking black tea also appears to be linked with a reduced risk of Parkinson's disease among people who smoke cigarettes.

Possibly Ineffective for...

  • Bladder cancer. People who drink tea, including black tea and green tea, do not seem to have a lower risk of bladder cancer compared to those who don't drink tea.
  • Breast cancer. People who drink black tea do not seem to have a lower risk of breast cancer compared to those who don't drink black tea.
  • Colon and rectal cancer. Some early research suggests that drinking black or green tea might be linked with a lower risk of colon and rectal cancer. However, most research shows that drinking tea is not linked with a lower risk of colon and rectal cancer. In fact, some early research suggests that drinking higher amounts of black tea might be linked with an increased risk of colon and rectal cancer.
  • Diabetes. Early research suggests that taking an extract of black and green tea does not improve average blood sugar levels in people with diabetes. Other early research suggests that drinking at least one cup of black tea per day is not linked with a lower risk of developing type 2 diabetes in Japanese adults.
  • Cancer of the lining of the uterus (endometrial cancer). Women who drink more black tea do not seem to have a lower risk of developing endometrial cancer compared to those who drink less.
  • Cancer of the tube connecting the throat and stomach (esophageal cancer). People who drink higher amounts of black tea do not seem to have a lower risk of developing esophageal compared to those who drink less.
  • Stomach cancer. Some early research suggests that drinking black or green tea might be linked with a lower risk of stomach cancer. However, most research shows that people who drink black or green tea do not have a lower risk of stomach cancer. In fact, some early research suggests that people who drinking higher amounts of black tea might have an increased risk of stomach cancer compared to those who drink less.
  • Lung cancer. Green tea and black tea contain chemicals called phytoestrogens. Some early research suggests that men who get more phytoestrogens in their diet have a lower risk of developing lung cancer than men who do not get these chemicals. However, drinking black tea is not linked with a reduced risk of lung cancer and may even be linked with an increased risk.

Insufficient Evidence to Rate Effectiveness for...

  • Hardening of the arteries (atherosclerosis). Early research suggests that people who drink black tea have a reduced risk of having their arteries become hardened compared to those who don't drink black tea. This link is stronger in women than men.
  • Heart disease. Some early research suggests that people who regularly drink black tea have a lower risk of developing heart disease. However, other research suggests that drinking black tea is linked with an increased risk of heart disease becoming worse or causing death.
  • Cavities. Early research suggests that rinsing with a black tea extract might help prevent cavities.
  • High cholesterol. It is still not clear if drinking black tea helps to reduce levels of cholesterol in the blood. Some research shows that black tea might reduce total cholesterol and low-density lipoprotein (LDL or "bad") cholesterol in people with normal or high cholesterol levels. However, other research shows that drinking black tea does not have these effects.
  • High blood pressure. Some early research suggests that people who regularly drink green or black tea have a lower risk of having high systolic blood pressure, which is the top number of a blood pressure reading. Also, some research shows that drinking 4-5 cups of black tea per day reduces systolic blood pressure in people with normal or high blood pressure. However, many studies show that drinking black tea does not reduce blood pressure in people with normal or high blood pressure.
  • Kidney stones. Women who drink one cup of tea, such as black tea, per day seem to have an lower risk of developing kidney stones compared to those who don't drink tea.
  • Pancreatic cancer. Some early research suggests that drinking black tea is linked with a reduced risk of pancreatic cancer. However, other research shows conflicting results.
  • Prostate cancer. Early research suggests that drinking black tea is linked with a reduced risk of prostate cancer.
  • Kidney cancer. Early research suggests that people who drink higher amounts of black or green tea have an increased risk of developing kidney cancer.
  • Stress. Early research suggests that drinking black tea for 6 weeks does not improve blood pressure, heart rate, or feelings of stress ratings while performing stressful tasks.
  • Stroke. Black tea contains chemicals called flavonoids. Early research suggests that eating a diet that contains flavonoids is linked with a lower risk of stroke.
  • Weight loss. Early research shows that taking a product containing black tea extract plus green tea extract, asparagus, guarana, kidney bean, and mate along with a combination of kidney bean pods, garcinia, and chromium yeast for 12 weeks does not reduce body weight in overweight adults.
  • Diarrhea.
  • Headache.
  • Stomach disorders.
  • Vomiting.
  • Other conditions.
More evidence is needed to rate the effectiveness of black tea for these uses.

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).

Quick GuideHeart Disease: Symptoms, Signs, and Causes

Heart Disease: Symptoms, Signs, and Causes

How does Black Tea work?

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.

Are there safety concerns?

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

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.

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.

Special Precautions & Warnings:

Children: Black tea is POSSIBLY SAFE when 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.

Are there any interactions with medications?



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

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.



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

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

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

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

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

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

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.



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

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

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

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

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

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

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

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).



Medications for depression (MAOIs)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

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.



Medications that change the liver (Cytochrome P450 1A2 (CYP1A2) inhibitors)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

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.



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

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.



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

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

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



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

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

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

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)
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 black tea might decrease how quickly the body breaks down riluzole (Rilutek) and increase the effects and side effects of riluzole.



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

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

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

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

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

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.



Water pills (Diuretic drugs)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

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.



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

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.



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

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.



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

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.



Medications for depression (Tricyclic antidepressants)
Interaction Rating: Minor Be cautious with this combination.
Talk with your health provider.

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).



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

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.



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

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

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

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.



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

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).



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

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

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

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.

Dosing considerations for Black Tea.

An 8-ounce serving of black tea provides from 40-120 mg of caffeine, the active ingredient.

The following doses have been studied in scientific research:

BY MOUTH:
  • For improving mental alertness: 1-3 cups of black tea containing 30-100 mg of caffeine have been used.
  • For heart attacks: At least 1 cup per day has been used.
  • For ovarian cancer: At least 2 cups per day has been used.
  • For preventing Parkinson's disease: Men drinking 421-2716 mg of total caffeine (approximately 5-33 cups of black tea) daily have the lowest risk of developing Parkinson's disease, when compared to other men. However, men who drink as little as 124-208 mg of caffeine (approximately 1-3 cups of black tea) daily also have a significantly lower chance of developing Parkinson's disease. In women, moderate caffeine intake (1-4 cups of black tea) per day seems to be best.
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Reviewed on 3/29/2011 12:35:40 PM

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