Herbal Supplements That Can Interact Negatively With Your Prescription Medication

Medicinal Herbs have been used and sold worldwide since ancient times.
Medicinal Herbs have been used and sold worldwide since ancient times. | Source

How Herbs Can Be Dangerous

Herbal supplements have been in use since the dawn of human history. Knowledge of herbal medicine formed the basis of medical science centuries ago, and in many ways, it still does.

More than one third of today's powerful prescription medications are based on herbs or medicinal plants, so it is not surprising that these same medicinal herbs taken as herbal supplements to stave off a cold or improve memory can also have serious side effects or interact dangerously with your prescription medication, especially if you are over 55.

At best, an herbal supplement will simply lessen or cancel out the effects of the medication your doctor has prescribed. At worst, it can have serious, life threatening side effects or set the stage for a dangerous medical emergency.

In the last twenty or thirty years, herbal supplements have become big business, and what is called " standardized extracts" of herbs, which are many times more potent than the ordinary plant, are sold online and in health food stores to heal and cure everything from insomnia to old age ( just kidding). It is these extracts which pose the greatest danger, especially to seniors whose bodies are more vulnerable and who are more apt than younger adults to be taking prescriptions for chronic illnesses such as asthma, heart disease, high blood pressure, glaucoma or diabetes with which herbal supplements could potentially interfere.

Herbal Teas and Whole Herb Capsules

Though powerful herbal extracts are the major concern, you should take care when using herbal teas and infusions or taking capsules of whole herbs as well, as in sufficient quantity these can also cause problems. A recent article in the AARP newsletter quotes an AARP Public Policy Institute survey of people age 50 and older which found that 59% of them had used supplements in the previous month and 52% of them took them daily. Less than half of the respondents said they talked to their doctors about the pills they took.

Here's the deal, garlic capsules are much much stronger than the clove of garlic you cook with. Take enough of them and if you are also taking an anti-coagulant blood thinner. You could theoretically bleed to death if you took a fall or got in an auto accident because your blood would not clot. The bottom line is that all herbal supplements of any kind need to be used with caution and common sense, especially when it comes to mixing them with prescription drugs.

It also goes without saying that children, pregnant women and nursing mothers should not take herbal extracts except under a doctor's supervision, but it is also true that all of us should periodically review any and all vitamins and herbal supplements we are taking. Just because we pick them up over the counter at the supermarket or pharmacy, does not mean that they are harmless placebos. Herbs are medicine too and can be very powerful.

Herbal extracts in capsules. Take with caution
Herbal extracts in capsules. Take with caution | Source

Dangerous Interactions

Here's an overview of some of the herbs and herbal extracts that can have dangerous interactions with prescription medicine or exacerbate certain conditions, particularly in people over 55.

  • Ginsing has been used for thousands of years, particularly in Asia, to increase energy and concentration, as an anti-aging potion and as a male aphrodisiac. However, it can interact negatively with diabetes medications, reduce concentrations of the anti-coagulant drug, Coumedin, and also reduce the effectiveness of some anti-depressants.
  • Kava Kava is a sedative herb used as a tea or in capsules. It is often used effectively for anxiety and insomnia. It should not be used by people taking anti depressants and it also has been shown to cause liver damage, including hepatitis and liver failure, in vulnerable people. It has a soporific effect which can make driving or operating heavy machinery dangerous, especially for older people. Use it carefully.
  • St John's Wort , often seen as a natural anti-depressant, is a potentially dangerous substance that can reduce the effectiveness of a number of prescription medications including blood thinning drugs, certain asthma medications, and many cancer drugs. It also interferes with the effectiveness of prescription antidepressants.
  • Licorice Root Licorice root tea is often used as a digestive aid. In capsule form, this herb is used as a natural treatment for stomach ulcers, sore throat and cough, It is also considered a digestive aid to aid bowel function. But be careful. Regular use can cause high blood pressure and water retention which can be especially dangerous for anyone with heart disease or high blood pressure.
  • Garlic Capsules are useful for everything from controlling high blood pressure to preventing tick bites, but in high doses, garlic can be a blood thinner and can interact with blood thinning drugs to create a serious risk of hemorrhage.
  • Aloe Vera used externally can help minor burns ( I keep a plant in my kitchen) and is perfectly safe, but taken internally, it is a powerful laxative that can interact negatively with blood sugar lowering medicines used to treat diabetes.
  • Ginger Many people take ginger capsules or drink ginger tea to help motion sickness or nausea of any kind. Ginger is also commonly used to treat joint pain and indigestion but in large doses, it can interact negatively with a wide variety of drugs including blood thinners, barbiturates, beta-blockers, and insulin,
  • Ginkgo biloba is often used to improve memory and concentration. It too is a blood thinner. Here is a list of drugs it can potentially interact withAspirin, warfarin (Coumadin), ticlopidine (Ticlid), clopidogrel (Plavix), dipyridamole (Persantine)
  • Ephedra( Ma Huang) is used to treat respiratory problems, colds and allergies and as a female tonic. It is an ingredient in many over the counter cold remedies. It works by stimulating the nervous system and can cause irrlegular hearbeat and insomnia among other things. It should be used with caution and not by anyone taking MAO inhibitors( serious high blood pressure can result) or diuretics, beta-blockers, or [ACE] inhibitors) because Ephedra can interfere with the effectiveness of these drugs.


A Growing Problem

As the sheer number and variety of both pharmaceuticals and herbal supplements grows, the chance of a dangerous interaction occurring multiplies exponentially. It is a growing problem for physicians and pharmacists as well as patients. In addition, while prescription medicines are manufactured according to exacting standards and monitored closely, Herbal supplements can vary greatly in terms of the percentage of active ingredients the contain as well as what else is in them. They are not subjected to the same rigorous tests and standards as pharmaceuticals which can create problems for people taking them as medicine for specific conditions.

The bottom line is that, whatever your age, but particularly if you are 55 or older, you need to find out everything before you start a new health regimen of any kind. . Before you order a vitamin or herbal supplement online or start taking something on the advice of a friend, do your homework and consult with your doctor or pharmacist to find out what, if any, effect any herbal supplements you take will have on your health as well as how they might interact with any prescription medications you now take. Herbal supplements and prescription medications can both be powerful life enhancers or potential killers, depending on how intelligently they are used.

Everything has consequences. Everything has side effects. Make sure you are making an informed choice before you put anything in the way of medicine into your body.

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Comments 42 comments

Aya Katz profile image

Aya Katz 4 years ago from The Ozarks

Robie, thanks for pointing out this problem. Drug interactions can be deadly, and herbs and drugs are not all that different.

However, the bigger problems is prescription drugs -- not herbs. Doctors prescribe too many of them and pretend that a person on those drugs can lead a normal life, when the ability to use herbal supplements is greatly curtailed by the prescribed drug.


robie2 profile image

robie2 4 years ago from Central New Jersey Author

I totally agree with you Aya, that Drs ( in the USA at least) very often over-prescribe, and some are no better than legal drug pushers, but on the other hand, there are times when only strong prescription drugs will do. I am thinking of a friend with serious Rheumatoid Arthritis who tried to go the natural route and ended up on one of those major new RA intravenous drugs-- it has changed her life.

Everything has side effects, it is a question of whether the game is worth the candle or not-- in the end we all need to be our own advocates and opt for what we think is in our own best interests. The best medicine is preventative medicine-- I totally agree with that.

Thanks for a great comment and for stopping by and taking the time to read, Aya


billybuc profile image

billybuc 4 years ago from Olympia, WA

Quite interesting my friend and some info I did not know. I'll be sharing this with my better half for sure. Great hub!


robie2 profile image

robie2 4 years ago from Central New Jersey Author

thanks, billybuc, glad you found it useful and thanks for stopping by and taking the time to comment.


Frieda Babbley profile image

Frieda Babbley 4 years ago from Saint Louis, MO

Very thorough and very important information. Had no idea, for example, that ginko was a blood thinner too; makes sense, but not something you think about.

I really agree with Aya's comment. Either way, it's super important to know this info, especially since people eat foods and drink drinks with herbs and may not even be aware of what they are doing to themselves because these herbs are not taken in supplement form necessarily.


CR Rookwood profile image

CR Rookwood 4 years ago from Moonlight Maine

Great hub. I didn't know most of this. I don't take many supplements (except fish oil and vitamin D, because fish in the midwest...uh, no), but it does bother me sometimes how everybody is a doctor these days. I've learned to keep my own counsel and find doctors I trust, not pill pushers. That way when I do really need a med, it's between me and a trusted professional, not me and a commercial on TV or advice online. I also totally agree that the older you get, the more this matters. Thanks, robie. Voted up!


robie2 profile image

robie2 4 years ago from Central New Jersey Author

Thanks for your input, Frieda and CR-- you both make great points. Thanks for stopping by. Much appreciated.


hinazille profile image

hinazille 4 years ago from Dominica (West Indies, The Caribbean) :D

Although I agree that some herbs do interact with prescription medications, unless you are taking the herbs in a abnormally high quantity, you should be ok. St Johns Wort does however have relatively serious interactions with meds such as Warfarin & antidepressants - so with that one its best to check in with the pharmacist if you are on other meds...


robie2 profile image

robie2 4 years ago from Central New Jersey Author

You are right about many herbs, hinazille,but some herbs, even in low doses will render a medication less effective unless a doctor of pharmacist knows about it and changes the dosage.....and some people take mega doses of herbal extract capsules without a second thought not reallizing that they shouldn't. Thanks for stopping by and taking the time to read and comment..... much appreciated


hinazille profile image

hinazille 4 years ago from Dominica (West Indies, The Caribbean) :D

Robie, you are so right about people taking bumper doses of herbal extracts - whenever I sell herbal or natural remedies, I enquire about any other medications they may be taking because once or twice I had patients buying St Johns wort and taking it whilst they were on Warfarin tabs and their anti coagulant nurses couldn't figure out why the INR levels were fluctuating so much...

voted up and interesting - definitely looking forward to reading more of your hubs... would love to hear your take on some of mine too so drop by when you get a minute :)


tammyswallow profile image

tammyswallow 4 years ago from North Carolina

I didn't realize there were so many herbal treatments that could interact with prescriptions. Excellent and important information!


stephhicks68 profile image

stephhicks68 4 years ago from Bend, Oregon

Great hub - I have always heard that herbal supplements can negatively impact prescription medications. This is a super guide. Best, Steph


robie2 profile image

robie2 4 years ago from Central New Jersey Author

following you now Hinazille, and looking forward to reading your hubs too-- nice to know you:-)

Tammyswallow and Steph-- it always amazes me that people really don't know how dangerous the interactions can be. I don't mean that people should not take supplements, only that they should do so knowledgabley


Sally's Trove profile image

Sally's Trove 4 years ago from Southeastern Pennsylvania

This is an excellent article about common herbal supplements. Because we're exposed to so much hype about the miracles certain supplements are credited with and too little reality, your article takes a needed cautionary view.

Any time my mother has had to undergo general anaesthesia, her surgery prep begins two weeks in advance with eliminating all vitamins and supplements (she takes quite a few) from her body. Although this requirement for surgery always made sense to her and to me - remove anything that can impact the effects of the aneaesthetic or interfere with monitoring vital signs - I didn't realize just how important this requirement was until reading the information here.

My mother's vitamin and supplement regimen is monitored by her physician, but I wonder when the two of them last sat down for a review. I'll definitely share this info (and the resources it points to) with her.

Up, interesting, useful, and IMPORTANT!


robie2 profile image

robie2 4 years ago from Central New Jersey Author

Thanks ST-- there's many a slip twixt cup and lip, like they say. Your mother is wise to keep her doctor in the loop and to stop everything two weeks before surgery. There are far too many accidents and while vitamins and suppliments are very important, and where practical should be used in preference to pharmeceuticals-- it is wise to remember that both herbal extracts and pharmeceuticals are both powerful medicinal potions and one should make sure they are not fighting each other when one is taking both. Thanks for a wonderful comment, as always ST.


robie2 profile image

robie2 4 years ago from Central New Jersey Author

Thanks ST-- there's many a slip twixt cup and lip, like they say. Your mother is wise to keep her doctor in the loop and to stop everything two weeks before surgery. There are far too many accidents and while vitamins and suppliments are very important, and where practical should be used in preference to pharmeceuticals-- it is wise to remember that both herbal extracts and pharmeceuticals are both powerful medicinal potions and one should make sure they are not fighting each other when one is taking both. Thanks for a wonderful comment, as always ST.


JamaGenee profile image

JamaGenee 4 years ago from Central Oklahoma

robie, you already know where I stand on the current over-medication of America. So my take on the information in this hub is when there's an herbal extract/capsule that produces the same result as a prescription drug doctors and BigPharma are pushing to fund their new Beemers - except in specific cases such as your friend with RA - drop the drug AND the doctor and take the supplement instead.

I do have to wonder, though, why anyone who's even semi-mobile and not totally bed-ridden is taking Coumadin on a daily basis. I was on it while in the hospital for 5 weeks with a shattered elbow and broken pelvis, but was not instructed to stop taking it when I went home. Concerned I could conceivably bleed to death from a slip of the razor while shaving my legs, I called my doctor, who said there was no need to take it once I was out of the hospital. Coumadin, or any blood thinner for that matter, is beneficial ONLY in specific situations, but outside those parameters is an extremely dangerous and life-threatening drug.


robie2 profile image

robie2 4 years ago from Central New Jersey Author

Well, not having completed my MD degree, I would not dare to comment on why people are on Coumadin, but I am told it is prescribed to people who have had strokes and heart attacks to prevent blood clots and is effective for that. Garlic in sufficient quantity, will also thin the blood-- but you would have to consume a ton of garlic capsules to do what one Coumadin tablet does. But the point is-- use one or the other-- not both. BTW a woman here in town who was on Coumadin after having had a stroke, had a minor automobile accident in which her head banged the windshield. She went home thinking it was just a fender bender--and got a terrible headache-- died on the way to the hospital-- turns out she was bleeding internally and didn't clot because of the Coumadin.

Thanks for a great comment as always Jama


kittythedreamer profile image

kittythedreamer 4 years ago from the Ether

Very well-written and informative. I don't think many people realize how herbs & some foods can have interactions with the medicinal drugs they take. Thanks for writing this and making people aware. :) Voted up, useful, and awesome.


robie2 profile image

robie2 4 years ago from Central New Jersey Author

Why thank you kitty--for the kind words about this hub and for stopping by and commenting.


Nell Rose profile image

Nell Rose 4 years ago from England

Hi, great informative hub, and definitely bookmarked. I have Asthma inhalers, and thyroid med, so this is really helpful, thanks nell


robie2 profile image

robie2 4 years ago from Central New Jersey Author

HI Nell, glad you liked the hub and found it helpful--thanks for stopping by:-)


Pamela99 profile image

Pamela99 4 years ago from United States

I am on several prescriptions and I take vitamins, but have been wary about many herbal supplement. Your article has excellent information on the most common supplements and is very helpful. Voted up and useful.


robie2 profile image

robie2 4 years ago from Central New Jersey Author

Glad you found the hub helpful, Pamela99 and really happy to see you here. Thanks for stopping by and taking the time to comment.


Pamela N Red profile image

Pamela N Red 4 years ago from Oklahoma

Great information, Robie. It's very important that we tell our doctor every supplement and herb we take no matter how insignificant we think it is. It's also a good idea to do our own research on each and every herb because unfortunately many physicians aren't educated on the side effects or interaction.

Herbs are a great help to our health but we have to do our homework to find out all the information about them.


robie2 profile image

robie2 4 years ago from Central New Jersey Author

Exactly, Pamela-- I take vitamins and herbal extracts myself, but use them with care and my doctor is aware of everything I take. I find that nurses and pharmacists often know even more than doctors about the interactions between herbal extracts and pharmaceuticals. \\

Thanks for commenting-- always really nice to see you:-)


RTalloni profile image

RTalloni 4 years ago from the short journey

Such a good look at being careful about taking herbal supplements. It is important to keep the fact that they can be harmful if used carelessly. Glad to see this topic highlighted so well!


cloverleaffarm profile image

cloverleaffarm 4 years ago from The Hamlet of Effingham

As an herbalist, I say "Thumbs Up". It is nice to see an article that actually talks about the proper use of herbs. While herbs are natural, they are medicine. Many more that you did not mention can interact with meds. Lemon balm is one that comes to mind. Also, because they are from plants, many people who have allergies should not take a plant from the same plant family. IE; Chamomile. It is from the daisy family.

Great hub. Voted up +


Larry Fields profile image

Larry Fields 4 years ago from Northern California

Hi robie2. I liked your hub, especially your emphasis on the fact that everything has side-effects.

There are also food-med interactions. For example, grapefruit affects the liver enzyme CYP3A4, which in turn, affects the rate at which certain medications are cleared from the system.

For anyone who wants to do a 'brown bag review' of all their meds and supplements, I'd recommend making an appointment with your pharmacist outside of his regular working hours, and of course, pay him for his time and expertise.

Pharmacists are usually more knowledgeable about these things than physicians, who typically believe everything that the pharmaceutical companies tell them, and who tend to be less than honest with their patients.

Voted up and shared.


robie2 profile image

robie2 4 years ago from Central New Jersey Author

Thank you cloverleaffarm--that is quite an accolade coming from an herbalist. Yes, I was surprised at how many herbs can be dangerous-- I found many, but the interactions were also many and a bit confusing so I just picked out a few, but it is an important subject, I think, especially for those of us ( like me, not you) who are a bit "long in the tooth" I'd love to see someone with your expertise do a more comprehensive hub on the subject ( hint hint) There is so much that most of us don't know. Thanks for stopping and commenting. I'm going off to follow you now:-)


robie2 profile image

robie2 4 years ago from Central New Jersey Author

Ohmygoodness, I've gotten out of sync here-- so sorry

Hello RTalloni-- I'm so glad you liked this hub and I totally agree that it is something we should all pay more attention to.

HI Larry Fields-- I'm glad you liked this one too, and I totally agree with you about nurses and pharmacists. My pharmacy asked me for a list of vitamins and supplements a few years ago and they have it on file-- I suppose I should update it. The brown bag review is a good idea


cloverleaffarm profile image

cloverleaffarm 4 years ago from The Hamlet of Effingham

robie2, I think that would be more of a book...lol. Thank you for the complement. Have a great day!


2patricias profile image

2patricias 4 years ago from Sussex by the Sea

This is a useful and interesting hub (voted up and shared). Here in the UK the herbal supplements industry is big business. We live in a town with a high percentage of elderly people. There is an independent health food shop with a large section of supplements, plus they are available in the drug stores and grocery stores. We know they are popular with the elderly - including those who are our relatives. The funny thing is, prescription medicine is available to those over 60 at no charge (paid for by the taxpayer). Supplements cost significant amounts of money. Some of our relatives spend a lot on supplement, don't tell their doctors, then wonder why their medicine doesn't work.

Your hub gives the clear message to tell your doctor about any supplements you take, and ask if they interfere with prescription meds.


robie2 profile image

robie2 4 years ago from Central New Jersey Author

Exactly, 2 Patricias. Just because herbs are natural and not manufactured in a lab, doesn't mean they are not powerful medications. Both young and old should remember that, but for the elderly it is more important because a) they tend to have more chronic conditions and thus take more medication and b) medication of any sort has a stronger effect on older people.

Thanks for stopping by. Always good to see you.


Max Clayne profile image

Max Clayne 4 years ago

I know Where this picture is taken from, this is morocco :)


robie2 profile image

robie2 4 years ago from Central New Jersey Author

I believe you are right Max-- you can check via the source link to flickr creative commons if you want to-- it's such a great pic I had to use it. Thanks for stopping by:-)


writeronline 4 years ago

OK, so I stopped taking warfarin in favour of daily enteric-coated aspirin to thin my blood, which I need to do because I have chronic atrial fibrillation and could die from clots caused by the heart beating inefficiently and not fully clearing the chambers of blood, but I also have high blood pressure which my Doctor insists I take medication for, even though I try to self-manage it by maintaining an appropriate BMI (body mass index) with daily exercise and a diet of quality foods that also where possible are low GI so I can forestall the diabetes we're told is coming for us all, just because we live in the Western world; I take Omega 3 capsules in high doses to help fight lifetime depression, in preference to prescription anti-depressants which I have at times been forced to take, and also to help ease joint pain and enhance mental acuity, daily garlic capsules to ward off colds nd flu, in conjunction with vitamin C tabs; but now you tell me that garlic and blood thinners are a potentially lethal combination so I'm worried, although I feel confident that the daily dose of milk thistle that I take to help my liver clear the residue of digoxin which my Doctor has prescribed as an essential part of maintaining heart health even though it's a known toxin, (and of course, the almost daily intake of a 'wee dram' of an evening), because God knows, you gotta take care of your own health as you get older - who can afford the cost of fixing the ailments that a preventive attitude and practical self-care could potentially forestall until what's euphemistically called 'old age' takes you?

Other than that, I try and laugh as often as possible, at least once a day. So far, haven't found a pill that makes me feel as good as that.. although it can be difficult on those days that coincide with a trip to the dentist, it's always seemed incongruous to me that the place you go to enhance your smile is the same place that, at bill time, can wipe it right off your face..

Anyway..thanks for this article, Robie, it's certainly helped me to learn more about "Herbal Supplements That Can Interact Negatively With Your Prescription Medication."


robie2 profile image

robie2 4 years ago from Central New Jersey Author

Good Grief writer-- you take a lot of stuff:-) But, clearly, you have it all worked out with the medical professionals, which is a good thing. It totally agree with you about the dentist. I have more caps and crowns than the Queen of England, not to mention a couple of implants. It is ust horrifying-- ahhhh well now that you know all the bad stuff that can happen between Herbal supplements and Prescription meds, just relax and have a nice cup of tea.... thanks for stopping by.


MarleneB profile image

MarleneB 4 years ago from Northern California, USA

Wow! Of all the things on your list, I do take garlic capsules to help fight against mosquito bites. Since taking the garlic capsules, I have been able to win the battle against mosquitoes. But, when I read your notes on how too much garlic can interfere with blood pressure, I was happy I read your hub. I take high blood pressure medicine and your information is a "need to know" fact that should be on the garlic capsule label. Thank you for your enlightening hub.


TIMETRAVELER2 profile image

TIMETRAVELER2 3 years ago

You've written a very important article here, and I hope it gets read by many people. One thing, though: I thought licorice root lowered blood pressure rather than making it higher? I've read this in several places, unless what I've read is referring strictly to licorice itself. Let me know, will you? Great work here and voted up.


robie2 profile image

robie2 3 years ago from Central New Jersey Author

Thanks Timetraveler-- I'm going to re check the info on licorice and will let you know. Thanks for pointing that out-- and I'll definitely get back to you and change the hub information if I am wrong. Thanks so much for taking the time to comment-- much appreciated.


TIMETRAVELER2 profile image

TIMETRAVELER2 3 years ago

No problem...I may be wrong on that one because while I know this is true for regular black licorice candy, it may not be so for the supplement, although I don't know why that would be different. I was taking the candy for heartburn without realizing that it lowered blood pressure. Fortunately I only did it randomly because I suffer from VERY low blood pressure and this really could have given me problems. I'll wait to hear from you on this.

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