pitcher of grapefruit juice

Speed kills, especially when it comes to pills. Everyone is in such a hurry these days that it’s rare for physicians to provide detailed instructions about how to take prescribed medicine. You probably won’t learn about critical food and drug interactions unless you take time to ask questions.

Pharmacists are overwhelmed, so they hardly ever interact directly with patients to give them advice. Pharmacy technicians may be good at counting pills and ringing up bills, but they don’t have the training to counsel people about food and drug interactions.

Patients are also pressed for time. Few people take the time to read instructions that might be provided with a prescription or over-the-counter medicine. But how you swallow your medicine matters.

Food and Drug Interactions

Do you take your pills at breakfast? If you wash them down with orange or apple juice, drink a cup of tea or coffee or eat yogurt or bran cereal, you could be reducing the effectiveness of certain medications.


People taking alendronate (Fosamax) for osteoporosis, for example, have been drilled that the pills must be taken on an empty stomach at least half an hour before the first cup of coffee or tea (with tap water, not fancy mineral water). Otherwise, you might as well throw the pill away, as it will not be absorbed adequately.

Aliskiren or Levothyroxine:

Taking the blood pressure pill aliskiren (Tekturna) with apple juice dramatically decreases the amount of medicine that gets into the blood stream. Coffee or tea can reduce the absorption of the thyroid hormone levothyroxine (Levoxyl, Synthroid, etc). So can mineral supplements like calcium or iron found in many multivitamins.


When doctors prescribe warfarin (Coumadin) for a blood clot in the leg or the lung, they may warn their patients to go easy on green vegetables. Broccoli, cabbage, salad and spinach are all rich in vitamin K that could counteract the anticoagulant activity of warfarin.

Far more controversial, however, is the cranberry-Coumadin interaction. One study found no interaction between warfarin and cranberry juice (British Journal of Clinical Pharmacology, July, 2010).

There are, however, numerous case reports in the medical literature describing an increased bleeding risk when people on warfarin also consume cranberry sauce or juice. One patient had a dramatic rise in the blood thinning effect (INR) after starting to drink cranberry juice. He died six weeks later of a hemorrhage (BMJ, Dec. 20, 2003).

One reader recently shared this experience: “My husband’s INR increased one year around Thanksgiving, when we had cranberry sauce several days in a row. He also reacted one spring after we had rhubarb sauce several days running.”

Dozens of drugs interact with grapefruit, but warnings are not always prominent. Some of the most popular include cholesterol-lowering meds such as atorvastatin, lovastatin and simvastatin. The powerful heart drugs amiodarone and dronedarone (Multaq) become more dangerous with grapefruit on board.

Since foods and beverages can have a profound impact on many of the medicines you take, it is worth spending a few minutes to quiz your doctor and pharmacist about all potential food and drug interactions. Don’t be in such a hurry that you put your health at risk.

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  1. Holly
    Ontario, Canada

    My mom takes alot of pills for depression,blood pressure, nerve damage and heart/stroke. She also drinks a lot of lemon juice mixed in her water. She sometimes finds that she is a little shakey on her feet. Cold the lemon juice be an issue?

  2. Chand
    Eluess Texas

    My wife has been taking Zolfresh(zolpidem tartrate) 10 mg with Fluanxol 0.5mg (2tablets each) after dinner since almost 15years for depression / sleep . Can she take these medicines before dinner say one 1 hour early

  3. Pat
    Ann Arbor MI

    This is such great information for me, who takes almost all her meds with coffee. The service that the Graedons provide on this site is inestimable. Thank you so very much. This is one site I will never delete.

    • Suzanne

      My doctor says to take blood pressure meds with orange juice and this site says not to. My blood pressure had been low 98 over 57. What should I do?

      • Barbara
        Tenerife of

        A am taking blood thinner and have to have a daily diet of vitamin k do not know what to take and what not ?

  4. Andrew Gibbons
    East London South Africa

    I would like to know if taking a sleeping pill like zolpedem with any kind of fruit juice is dangerouse

  5. austen

    THOUGHT provoking issues on drug Interactions. I suggest a comprehensive list be handed down to patients for every Doctors visit with drug prescriptions.

    • austen

      I mean comprehensive list of possible drug interactions with lemons and Grapefruit!! Etc.

      • Julie

        That’s a great idea and the same thing I told my Dr. I am on several meds for several reasons and just found out that by taking one of my seizure medications called phenobarbital, prescribed by my neurologist and taking a sleep medicine called bellasomra prescribed by my PCN, together could have major interactions such as coma and/or death. Good thing I had asked my Dr if the new sleep medication was ok to take with my other meds cuz he didn’t even look at my Rx list till I said something.

  6. Malibu

    IV just been put on colestrol pills, I’m also on heart tablets ,blood pressure pills, anti depressent and quite a few others including warfrain, I had know idea that grapefruit juice wasn’t good if your on certain pills I drink loads of pink grapefruit juice.

  7. kim thomas

    After eating a small grapefruit and small orange my sugar went to 399 so thought I’d check online for effects from them I am also on colesterol meds.

  8. DM

    Isn’t there a problem between licorice and blood pressure meds? It seems to me Daddy couldn’t have grapefruit or licorice.

  9. J S Peterson

    I’ve been taking Coumadin since 1996 due to a mitral valve replacement brought on by Rheumatic Fever in my younger days. While I found this article informative, particularly the cranberry ‘controversy, I was surprised that no real mention was made of the Warfarin/Coumadin and grapefruit juice connection.
    Granted, most pharmacies put a grapefruit warning on the bottle, but I’ve known many folks who ignored that warning. They either love grapefruit that much or they are willing to tolerate fluctuations in their INR. Their logic seems to be, “I can drink orange juice but not grapefruit? Ha!”
    I would’ve like to have seen a little more information on the effects grapefruits have on blood thinner users. Also some patients are on the ‘more powerful’ heart meds you mentioned AND warfarin/Coumadin potentially making grapefruit products a double whammy.
    Lastly, and slightly off topic, as a long time Coumadin user, neither my long term G.P. nor my cardiologist will allow me to take Warfarin due to ingredient and filler differences that very by manufacturer. I’ve read up on it and there’s a lot to it. I think an article on that (if not already done) would be beneficial.

  10. JS

    My husband takes one prescription drug a half of a Losartan/50/12.5MG, plus 2 Red Yeast Rice, One vitamin D3 2000 I.U. 1 CoQ10 100 mg and 1 MegaRed 500 mg and a low dose aspirin each morning with his cereal. He just pops them in his mouth and swallows them with his cereal. No water or anything to drink. He does have coffee sometimes a little later. I always worry that he should be taking them with water or some other fluid. Is this a problem or not? Thank you. Jean S
    People’s Pharmacy response: We always think it is a good idea to wash pills down with water!

  11. RF

    I have been taking Zocor (simvastatin) for awhile and avoiding grapefruit as directed. Then I read something about pomegranate juice not being a good thing to take as well, as it can have a similar effect to grapefruit. I was a daily drinker of pomegranate juice, but when I stopped, I found I had much less muscle pain.

  12. Marissa

    My husband was prone to leg cramps for years until I started using soap under the sheet. His leg cramps disappeared for a few years and then suddenly reappeared. I realized the Ivory soap that I had routinely switched to recently was an old bar, not used, but definitely 6 months or more old. It also looked like it had been wet (although still wrapped). The cramps came back immediately. This week I bought new soap and the cramps seem to have disappeared! Hurrah!

    • julie

      Are you talking about bath soap shavings or powdered soap?

  13. Penny Hammack

    A friend asked me about Seville oranges. I looked them up and discovered that they have the same effect as grapefruit (also some lemons and limes). Seville oranges are tart to bitter and used primarily for orange marmalade and other cooking where a tart taste is desired. I don’t think you’ll ever see marmalade listed in the dangerous interaction section of your prescription.

  14. MTB

    Sometimes the interaction is helpful. For instance drinking grapefruit juice with Cialis increases the effect. In this case it’s a good thing ;-)

  15. JDS

    Is there any correlation between Buproprian (Welbutrin) and coffee? I am taking it to help me quit smoking and it is having no effect whatsoever. I do drink a LOT of coffee and usually take my pill every morning with coffee.

  16. Karen

    Given that we know both cranberry and grapefruit interfere with various meds, albeit differently, it’s probable that many many more of the “new” fruits and juices will as well. Suspect pomegranate, myself. Wonder about fennel.
    It will be interesting to observe, and no easy answers. The healthier one’s diet gets, the more variety, and the more chance of interaction with the drugs one still has to take.

  17. RKM, MD

    As a physician, I find it difficult to properly instruct patients on use of medication, and as you indicate, few read the instruction sheet – partly because they are generally excessively long and detailed – understandably for legal reasons.
    One solution I have found: I keep a list of key questions on the meds I most often prescribe, and I call or ask on next appointment these questions. If they don’t know, it is often enough to stimulate them to read the instructions.
    People’s Pharmacy response: That sounds like a good idea. We trust that if the patient comes with key questions to ask you, that facilitates the dialog.

    • John

      This is actually a response to People’s Pharmacy who responded to Dr. RKM (I assume that is his/her initials).

      It is the Doctor and not the patient who has a list of common questions on medications prescribed. The Doctor asks those key questions to the patient, much like a quiz but I’m sure done in a casual, but professional conversation.

      It is a good indicator if the patient doesn’t know the answer, because then it stimulates and encourages them to read the drug documentation.

      I am prescribed many medications and that is the first thing I read prior to taking a drug that has been prescribed for the first time.

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