Health & Wellness

Grapefruit Is a Culprit in More Drug Reactions

by Roni Caryn Rabin –

The patient didn’t overdose on medication. She overdosed on grapefruit juice.

The 42-year-old was barely responding when her husband brought her to the emergency room. Her heart rate was slowing, and her blood pressure was falling. Doctors had to insert a breathing tube, and then a pacemaker, to revive her.

They were mystified: The patient’s husband said she suffered from migraines and was taking a blood pressure drug called verapamil to help prevent the headaches. But blood tests showed she had an alarming amount of the drug in her system, five times the safe level.

Did she overdose? Was she trying to commit suicide? It was only after she recovered that doctors were able to piece the story together.

“The culprit was grapefruit juice,” said Dr. Unni Pillai, a nephrologist in St. Louis, Mo., who treated the woman several years ago and later published a case report. “She loved grapefruit juice, and she had such a bad migraine, with nausea and vomiting, that she could not tolerate anything else.”

The previous week, she had been subsisting mainly on grapefruit juice. Then she took verapamil, one of dozens of drugs whose potency is dramatically increased if taken with grapefruit. In her case, the interaction was life-threatening.

Last month, Dr. David Bailey, a Canadian researcher who first described this interaction more than two decades ago, released an updated list of medications affected by grapefruit. There are now 85 such drugs on the market, he noted, including common cholesterol-lowering drugs, new anticancer agents, and some synthetic opiates and psychiatric drugs, as well as certain immunosuppressant medications taken by organ transplant patients, some AIDS medications, and some birth control pills and estrogen treatments.

“What drove us to write this paper was the number of new drugs that have come out in the last four years,” said Dr. Bailey, a clinical pharmacologist at the Lawson Health Research Institute, who first discovered the interaction by accident in the 1990s.

How often such reactions occur, however, and how often they are triggered in people consuming regular amounts of juice is debated by scientists. Dr. Bailey believes many cases are missed because doctors don’t think to ask if patients are consuming grapefruit or grapefruit juice.

Even if such incidents are rare, Dr. Bailey argued, they are predictable and entirely avoidable. Many hospitals no longer serve juice, and some prescriptions carry stickers warning patients to avoid grapefruit.

“The bottom line is that even if the frequency is low, the consequences can be dire,” he said. “Why do we have to have a body count before we make changes?”

For 43 of the 85 drugs now on the list, consumption with grapefruit can be life-threatening, Dr. Bailey said. Many are linked to an increase in heart rhythm, known as torsade de pointes, that can lead to death. It can occur even without underlying heart disease and has been seen in patients taking certain anticancer agents, erythromycin and other anti-infective drugs, some cardiovascular drugs like quinidine, the antipsychotics lurasidone and ziprasidone, gastrointestinal agents cisapride and domperidone, and solifenacin, used to treat overactive bladders.

Taken with grapefruit, other drugs like fentanyl, oxycodone and methadone can cause fatal respiratory depression. The interaction also can be caused by other citrus fruits, including Seville oranges, limes and pomelos; one published case report has suggested that pomegranate may increase the potency of certain drugs.

Older people may be more vulnerable, because they are more likely to be both taking medications and drinking more grapefruit juice. The body’s ability to cope with drugs also weakens with age, experts say.

Under normal circumstances, the drugs are metabolized in the gastrointestinal tract, and relatively little is absorbed, because an enzyme in the gut called CYP3A4 deactivates them. But grapefruit contains natural chemicals called furanocoumarins, that inhibit the enzyme, and without it the gut absorbs much more of a drug and blood levels rise dramatically.

For example, someone taking simvastatin (brand name Zocor) who also drinks a small 200-milliliter, or 6.7 ounces, glass of grapefruit juice once a day for three days could see blood levels of the drug triple, increasing the risk for rhabdomyolysis, a breakdown of muscle that can cause kidney damage.

Estradiol and ethinyl estradiol, forms of estrogen used in oral contraceptives and hormone replacement, also interact with grapefruit juice. In one case in the journal Lancet, a 42-year-old woman taking the birth control pill Yaz developed a very serious clot that threatened her leg several days after she started eating just one grapefruit a day, said Dr. Lucinda Grande, a physician in Lacey, Wash., and an author of the case report.

But Dr. Grande also noted that the patient had other risk factors and the circumstances were unusual. “The reason we published it as a case report was because it was so uncommon,” she said. “We need to be careful not to exaggerate this.”

Some drugs that have a narrow “therapeutic range” — where having a bit too much or too little can have serious consequences — require vigilance with regard to grapefruit, said Patrick McDonnell, clinical professor of pharmacy practice at Temple University. These include immunosuppressant agents like cyclosporine that are taken by transplant patients to prevent rejection of a donor organ, he said.

Still, Dr. McDonnell added, most patients suffering adverse reactions are consuming large amounts of grapefruit. “There’s a difference between an occasional section of grapefruit and someone drinking 16 ounces of grapefruit juice a day,” he said.

And, he cautioned, “Not all drugs in the same class respond the same way.” While some statins are affected by grapefruit, for instance, others are not.

Here is some advice from experts for grapefruit lovers:

  • If you take oral medication of any kind, check the list to see if it interacts with grapefruit. Make sure you understand the potential side effects of an interaction; if they are life-threatening or could cause permanent injury, avoid grapefruit altogether. Some drugs, such as clopidogrel, may be less effective when taken with grapefruit.
  • If you take one of the listed drugs a regular basis, keep in mind that you may want to avoid grapefruit, as well as pomelo, lime and marmalade. Be on the lookout for symptoms that could be side effects of the drug. If you are on statins, this could be unusual muscle soreness.
  • It is not enough to avoid taking your medicine at the same time as grapefruit. You must avoid consuming grapefruit the whole period that you are on the medication.
  • In general, it is a good idea to avoid sudden dramatic changes in diet and extreme diets that rely on a narrow group of foods. If you can’t live without grapefruit, ask your doctor if there’s an alternative drug for you.

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4 years ago

This is good news, only problem is some pharmacists and Dr’s are idiots. A few years ago my idiot Dr prescribed a dangerous combo of meds with no informed consent and even AFTER I mentioned I was taking a number of supplements. The pharmacy (safeway) never checked for interactions and even put pressure on me to pick up the medication after expressing concern about it. Two weeks later, brain, muscle, kidney and nerve damage. The only part I regret is the reaction didn’t kill me. Was brought to the hospital by ambulance and they did NOTHING but yell at me… Read more »

gail Joule
7 years ago

why don’t we hear about studies being made to use grapefruit in conjunction with meddications to decrease the amount of drug needed?

Evelyn Froisland
7 years ago

I agree. a list of drugs affected by grapefruit would be nice. I haven’t eaten grapefruit in years because I was taking Zocor. I like citrus especially oranges and use lemons in my tea. How do I know if they cause reactions too?

7 years ago

I agree with many of the previous comments. A list of all the affected drugs by grapefruit would be appreciated .

7 years ago

It would appear that the undisputed facts are that Big Pharma has bought our government, lock, stock and barrel. The training for all of our licensed medical people is either controlled or severely influenced by our federal government. This means that their license is constantly in jeapordy and that they must play ball with the established system. Are you with me so far??? In addition to Big Pharma, the licensed medical people are part of the enormous profit sharers of the system. They dare not warn you about any treatment or drug that would keep you from spending your money.… Read more »

Sharon I.
7 years ago
7 years ago

Seems to me like the smart thing to do would be get rid of the drugs you didn’t really need in the first place and keep the grapefruit and other natural things which promote health. You body has no idea what to do with the un-natural drugs and other toxins, whose only purpose are profits for big pharma and your doctor (quack). At 68 and never led a healthy lifestyle until about 5 years ago, I am now using better choices for my diet and I am on no drugs and feel better than I have in years.

Virginia Newcomb
7 years ago

I am 87 years old and take no medications. My cholesterol is higher than the doc would prefer, but I refuse to take any staten drug. I think they do more have than good. I eat veggies, fruits and mod. amt. of meat and get regular exercise, walking and riding my tricycle. I am able to take care of myself and my husband and do my own housework. I have much to be thankful for in these extra years to enjoy my family of 4 generations!

7 years ago

I am 87 and take no medications. My cholesterol is higher than the doctor would prefer, but I refuse to take a statin drug.
I take multivitamins and extra calcium and magnesium. I eat healthful food, lots of vegies and fruits and mod. amt. of meat, and I exercise regularly. I am thankful to be able to take care of myself and my husband and enjoy these extra years the Lord has granted me.

Ed Straub
7 years ago

I have checked the Bible, and found out, there is not drugs in Heaven, may be that’s why so many want to go the that other place. Yea, many will just not fit in, no sin, no hate, no drugs, it will be awful it they would wind up there.

7 years ago

Recent health/blood tests show me to be in good health. Being in my 60’s, I take no drugs or medications. I eat grapefruit every day. I never wanted to be an elderly person with a shelf full of drugs to take throughout the day. Drug commercials spend more time informing you of the side effects of taking the drug, and is usually followed by a commercial where attorneys are suing drug companies because of the damage from those side effects. Big Pharma and attorneys both score big paydays!

Ed Straub
7 years ago

So where is the list of drugs that are effected? I’m 71 years old and today look forward to the Rapture of the Church. I look forward to seeing My Jesus, and leaving this world. When I was young it was a wonderful country, but now it has turned evil. The world is got this mixed up idea or political correctness, calling evil good and good evil, and right wrong and wrong right. Wait a minute is that not what the Bible, King James Bible, say will happen in the last days? Wow, He’s coming soon, are you ready. God… Read more »

7 years ago

Here’s a novel thought. If grapefruit enhances the effect of certain drugs, then why not prescribe a LOWER dose of drug ALONG with grapefruit juice for people who drink it? Using less drug should lower the cost of the medicine, which would lower drug company profits and doctor kick-back, oh wait a minute. Now I get it…

Bud Donahue
7 years ago

I started a statin 15 years ago, and was cautioned against grapefruit juice at that time… Since then I have come to believe ‘juice’ is a waste of time and money… Never been healthier…

Dave Carpenter
7 years ago

Makes one wonder what other effects “natural” foods and drinks have on the body? Perhaps to the point where man made, expensive, drugs with side effects could be avoided all together in some cases? Modern medicine is a whole lot better than blood letting with leeches but has it reached a point where the need for revenue to Big Pharma out weighs the knowledge of the Physician? Doctors have many years of schooling but as in this story, “They (the Drs) were mystified”. Almost all Drs prescribe the drug most, which is pushed the hardest by the Drug company rep… Read more »

7 years ago

It’s easier and healthier to give up the pharmaceuticals and eat healthy food. A serving of grapefruit juice every morning is an integral part of my diet which allows that.

7 years ago

This is a great article. I love Grapefruit, due to high cholesterol my doctor put me on Lipitor. I noticed I would have this constant pain on the right side of my torso, like I had been kicked by a horse just under the ribs (and told the doctor about it a couple of times) One day my friend was here visiting from CA. (he is a Pharmacist) he seen me eating a grapefruit and said to me, you are on Lipitor, how can you eat a Grapefruit? I told him I eat it every day, well we figured out… Read more »

Ralph W Camp
7 years ago

I agree with Sue Ellen. A list would be most beneficial. I first encountered this situation about 20 years ago when I first started taking statins for high cholesterol. There was a printed warning attached to the bottle about taking grapefruit with it. However, I no longer see that warning on perscriptions and my doctor has not asked me about it ever. That’s whats scary!

Betty Birky
7 years ago

Definitely needed a link to the list of the 85 medications. Also along with the scientific name, the brand name/s of the drugs. Not all of us know what simvastatin is, for example.

Sue Ellen
7 years ago

It would have been nice if the article provided a link to the list of drugs that interact with grapefruit….

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