Green tea promotes wellness and health for most people. Research suggests that it may decrease blood pressure, boost the immune system, reduce the risk of some cancers and lower cholesterol, reports the University of California, San Diego Medical Center. Many of the herb's healing properties result from its high concentration of antioxidants called polyphenols. Side effects of green tea are generally mild, but it can cause unsafe drug interactions.
Common Side Effects
Green tea may cause increased heart rate, insomnia or nervousness due to its caffeine content. Green tea also contains tannins and chlorogenic acid which may cause a reduction in appetite, diarrhea or heartburn, reports the University of California, San Diego Medical Center.
Rare Side Effects
Certain weight loss products containing green tea may cause liver damage, warns the University of Michigan Health System. However, it is uncertain whether the damage stems from green tea or the other ingredients in these weight loss products. To err on the side of caution, researchers suggest you avoid consuming large amounts of concentrated green tea extract.
The University of Michigan Health System also reports that green tea, when taken with a meal, may inhibit iron absorption in a small number of healthy women. This could lead to an iron deficiency over time.
Drug Interactions
Green tea may inhibit the absorption of certain alkaline medications, and it can render the cancer drug bortezomib completely ineffective, warns the University of California, San Diego Medical Center. Some other drugs that green tea interferes with include adenosine, benzodiazepines, clozapine and lithium, reports the University of Maryland Medical Center.
Using green tea while taking medication for blood pressure, MAOIs or phenylpropanolamine can cause a severe spike in blood pressure. Do not take green tea supplements with aspirin, as this may increase your risk of bleeding. Using oral contraceptives or ephedrine with green tea may worsen caffeine-related side effects.
If you suffer from any medical condition, and especially if you take medicine for it, consult your doctor before taking green tea or any other supplement.
References
- University of California, San Diego Medical Center: Green Tea
- University of Michigan Health System: Green Tea
- University of Maryland Medical Center: Green Tea
- University of Southern California: Green tea blocks benefits of cancer drug, study finds
- Oregon State University: Micronutrient Information Center - Tea
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