The Polypharmacy Network

Polypharmacy Prevention
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What You Should Know About Green Tea?
By: Joanne Jansen PharmD and Anjanette Dymerski PharmD
Many people consider herbal supplements safe since they are natural. However, even natural things can be bad for you; for example, a bite from a black widow spider is natural and not good. Always discuss any new supplements with your doctor or pharmacist before taking them to make sure they do not interact with your medications or cause worsening of a disease you have.

It is important to remember that natural supplements and vitamins are not regulated by the Food and Drug Administration (FDA). This means that there may be ingredients in the products that are not listed. There is also no guarantee that the ingredients listed on the bottle are accurate.

Green tea is commonly used for:
• Improving ability to think and focus
• Weight loss
• Antioxidant effects: may slow aging and prevent damage to the body

While green tea may work in some people, there are many reasons you may not want to take it. Green tea has been known to cause liver damage and insomnia. It also contains high amounts of caffeine. Green tea may interact with some drugs and change or increase their effects. For instance, green tea interacts with all of these drugs and more:
• Amphetamines
     o methylphenidate (Concerta®, Ritalin® / Ritalin LA® / Ritalin SR®)
     o amphetamine and dextroamphetamine (Adderall®)
     o Cocaine
• Decongestants
     o pseudoephedrine (contained in the nonprescription cough/cold/allergy products that you have to get from the pharmacist) including:
          - Zyrtec D®
          - Sudafed® (but not PE)
          - Claritin D®
          - Alavert D®
          - Mucinex D®
          - Tylenol Cold Severe Congestion®
          - Tylenol Sinus Severe Congestion®
• Anticoagulants / Antiplatelets (blood thinners)
     o warfarin (Coumadin®)
     o clopidogrel (Plavix®)
     o dipyridamole (Persantine®, Aggrenox®)
     o aspirin
     o ticlopidine (Ticlid®)
     o enoxaparin (Lovenox®)
     o heparin
     o Ibuprofen (Advil®, Motrin®)
     o Naproxen (Aleve®, Naprosyn®)
     o Indomethacin (Indocin®)
     o Ketoprofen
     o Meloxicam (Mobic®)
     o Diclofenac (Voltaren®)
     o Oxaprozin (Daypro®)
     o Celecoxib (Celebrex®)
     o Piroxicam (Feldene®)

Natural products that may interact with green tea:
• Anticoagulants / Antiplatelets (blood thinners)
     o Garlic
     o Ginger
     o Ginkgo
     o Panax ginseng
• Other caffeine containing products
     o Coffee
     o Black tea
     o Cola
     o Guarana
     o Mate
• Weight loss products including:
     o Hydroxycut®
     o TrimSpa®
     o Hoodia®
     o Xenadrine®
     o Stacker 2®

Green tea can cause problems in people with certain diseases. If you have one of the following, discuss with your doctor or pharmacist whether you should take green tea:
• Anemia
• Anxiety
• Bleeding disorders
• Heart conditions
• Diabetes
• Glaucoma
• High blood pressure
• Liver problems
• Osteoporosis

Other things you should know about green tea:
• Tell your doctor you are taking this drug before you have surgery. You may need to stop it two weeks before surgery to prevent bleeding problems.
• Tell your doctor or pharmacist you are taking this drug before you start any new medications.
• Green tea may interact with many blood tests your doctor may take.
• Green tea may decrease the amount of iron and calcium you absorb from your diet.
• Side effects may include insomnia, anxiety, jitteriness, high blood pressure, nausea, vomiting, and diarrhea.

More information available at the Natural Products Database of The Pharmacist’s Letter.