Medicinal Herbs: Not to Be Taken (or Given) Lightly

As a small animal internist, the majority of my patients are referred by their family veterinarians.  By the time I first examine them, they are usually receiving a laundry list of conventional medications (antibiotics, nonsteroidal antiinflammatories, etc.) and/or complementary medications (herbs, homeopathic remedies).   I’ve always scrutinized the conventional medications on the list because their potential side effects and the ways they might impact my diagnostic and therapeutic planning.  I’ve tended to pay far less attention to the complementary medications because of my impression that these medicinals are unlikely to cause significant harm or interact unfavorably with other things I might prescribe. Well, there will be no more of this “ignorant bliss” for me! Not after reading, “A Review of the Potential Forensic Significance of Traditional Herbal Medicines” from the Journal of Forensic Science (January, 2010).  The author, Roger Byard, M.D. undertook a review of herbal medicines based on their increasing popularity (there has been a steady 10% increase in spending on botanical remedies in the United States) and the fact that access to such products is largely unrestricted- they can be purchased without prescription. Keep in mind that herbs are manufactured and sold without any FDA approval process.

Here are some of Dr. Byard’s comments and findings:

-An analysis of 251 Asian herbal products from stores in California identified arsenic in 36, mercury in 35, and lead in 24. There have been reports of lead poisoning and mercury poisoning in people caused by such contamination.
-Less expensive herbs are sometimes intentionally used to replace those that are more costly. A case is referenced in which an herb designed to promote weight loss was replaced with another. The unfortunate result for the patient was kidney failure.
-Accidental substitution can occur if plants are incorrectly identified or if the name is misinterpreted. Apparently, some traditional herbal preparations have multiple names. To make matters even more confusing, some herbal preparations that are different from one another go by the same name.
– Failure to process fresh herbs correctly can have serious consequences. Processing is designed to clean and preserve the desired material while removing or reducing any unwanted toxic components. The example provided was aconite root, a plant that must be soaked in water and boiled to reduce toxicity. Failure to do this can result in heart rhythm abnormalities and/or heart failure.
-Some herb manufacturers purposefully adulterate their products with drugs presumably to increase their efficacy. Yet no mention of this is made on the packaging. Examples of hidden products found in herbal preparations have included conventional medications to treat pain, inflammation, seizures, heart failure, and asthma.
-Herbal medicines can interact with conventional drugs and other herbs to cause undesirable side effects. For example, St. John’s Wort can decrease the blood level of some medications by impacting how they are metabolized within the liver.
-The American Society of Anesthesiologists has recommended discontinuation of herbal medicines at least two weeks prior to surgery because of their potential for causing complications. Although only eight herbs were identified as being potentially dangerous, they accounted for 50% of all single herb preparations of those sold within the United States. For example, Ginkgo has the potential to increase the risk of hemorrhage and Valerian can exacerbate the sedative effects of anesthetic agents.

Although Dr. Byard’s review is based on findings in human medicine, I have to believe that the general points he makes likely apply to veterinary medicine as well. His review has certainly served as a wake up call for me. If you use herbs, for your pets or yourself, perhaps this information will prompt you to think about things a bit differently as well. What is a practical approach for avoiding the potential pitfalls associated with herbal medications? I encourage you to consider doing the following:

  1. If you are giving herbs to your pet based on your own initiative, schedule an appointment with your vet to discuss and verify that what you are doing is reasonable and safe.
  2. Have a look at the blog I posted in July, 2009 ( called, “The Lowdown on Nutritional Supplements.” It will teach you how to use the ACCLAIM system to evaluate the quality of herbal products.
  3. Pick up a copy of the Physician’s Desk Reference (PDR) for Nonprescription Drugs, Dietary Supplements, and Herbs. It provides information about the indications, contraindications, and warnings for all commonly used herbs. This PDR is readily available via major online book vendors. I will certainly be using my own copy a whole lot more than ever before!

I hope I have not created fear or anxiety by presenting this information. Rather, my goal is to help you become the very best medical advocate possible. Now, like me, you know that herbal medications should not be taken (or given) lightly. If you provide herbs to your pet(s), I would love to hear from you. Please let me know which one(s) you are giving and whether you or your veterinarian initiated this treatment.

Best wishes to you and your four-legged family members for abundant good health.

Nancy Kay, DVM
Diplomate, American College of Veterinary Internal Medicine
Recipient, American Animal Hospital Association 2009 Animal Welfare and Humane Ethics Award
Recipient, 2009 Dog Writers Association of America Award for Best Blog
Recipient, 2009 Eukanuba Canine Health Award
Author of Speaking for Spot: Be the Advocate Your Dog Needs to Live a Happy, Healthy, Longer Life

Become a Fan of Speaking for Spot on Facebook

Please visit to read excerpts from Speaking for Spot. There you will also find “Advocacy Aids”- helpful health forms you can download and use for your own dog, and a collection of published articles on advocating for your pet’s health. Speaking for Spot is available at, local bookstores, or your favorite online book seller.



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9 Comments on “Medicinal Herbs: Not to Be Taken (or Given) Lightly

  1. I am very careful about anything I put in my body or any of the pets that I love. I have to say though that I place more trust in traditional medicine that has been practiced for thousands of years than allopathic medicine which is relatively new.
    I use a vet who is board certified in homeopathy (she studied with Pitcairn) and a vet who uses is certified in Traditional Chinese Medicine and Acupuncture.
    It’s important to remember that the FDA (who approved thalidimide, phen phen and vioxx among others) is a political group. I wish it wasn’t but as I say on my rado show all the time “Everything is political and everything political affects my dogs”.
    Dr. Kay, it sounds like you get a lot of sort of “last chance” pets who have everything but the kitchen sink being thrown at them. That’s difficult, I know from experience.
    While I am open to all kinds of medicine, surgery has it’s place as do allopathic pharmaceuticals, I’m glad that I have a core beliefs about health care that guide my choices for care in emergencies.
    Though I will admit that once when my 15 year old cat had a heart attack, heart transplant was something I talked to my vet about. (We go a bit nuts in emergencies, what can I say?) She lived to be 19 and it was her kidneys that went in the end, her heart was fine.

  2. Spot Speaks is more like Big Pharma Speaks…..You know I would have expected an M.D., a vet or some one else on big Pharma’s payroll to write about all the poisons in herbs and things not approved by the FDA (like the FDA cares about safety – follow the money) Why not write about just some of the poisons in legal drugs that are killing people and our pets every day. They warn of arsenic lead and mercury when (with FDA approval) they have been pumping mercury (thimerosal) into our babies and pets for years. Merck lied about taking it out and continued to pump it into babies. Still today, thimerosal is in flu shots and swine flu vaccines and most of our pet vaccines and God only know what else – theoretically as a preservative. Do some research on its value as a preservative.

  3. I think that Dr. Kay has made a very informative post here on her blog about natural supplements. Natural doesn’t always mean safe. Most western medicines are derived from some sort of plant base. And as western meds mix and give side effects, so can natural meds. Just because it grows and you can touch it, does not mean that a plant herb can be used without medical advise or counsel. Herbs can save people and pets – to a degree, those same herbs combined inappropriately can also kill humans and animals.

    We always recommend that anyone looking to work with natural herbal remedies consult a vet or herbalist that specializes in holistic healthcare for pets. An animals body is very different from our body, so what might work for us, may not work for them.

    For example, lets think of pets as they age, some pets loose valuable enzymes in their body to digest their food properly. For humans we might have a piece of pineapple after our meal to help us digest our food. For our pets, that would make them ill. They need special enzyme supplements that work with their bodies, their stomachs and their intestinal tract.

    Herbal medications should also be confirmed as clean. Some companies do not produce high quality supplements, some contain toxins like titanium dioxicide (makes the supplement white, same stuff they use in paint to make that white), other companies do not make supplements that are easily absorbed. Its always important to get proper counsel from a well educated and informed medical professional that can supply your pet with trusted herbal medications. Lead, mercury and other heavy metal toxins that are found in supplements might also be found to come from the pesticides that are sprayed on the herbs as they grow. Clean, high quality herbal supplements are easy to find from a reputable company that specializes in quality control of their product.

    Thank you Dr. Kay for sharing the importance of this information with your audience! Bravo!

  4. My dog and two cats see a holistic vet who does a really lovely blend of natural/herbal stuff and western medicine.

    My dog takes probiotics, fish oil, a cranberry supplement for recurrent UTIs, a Bach Flower remedy for anxiety (seems to help), and Tinkle Tonic (Couchgrass, Echinacea (purpurea), Marshmallow, Dandelion, and Horsetail). She also takes arnica after chiropractic adjustments.

    All of these were prescribed by my vet, and I bought them through her. I suppose I’m trusting that the stuff she has chosen is relatively safe/unadulterated. It does meet the ACCLAIM standard, except maybe the clinical portion- haven’t looked it up.

    I will be looking into a PDR for herbs though. I research everything I give on the internet first, but that’s just wading through a morass of junk, so a PDR is a great idea!

    Excellent blog post!

  5. I haven’t read this particular review, but it isn’t breaking new ground as all of the points quoted come from old papers. I think the conclusion is appropriate – if you’re interested in herbs, talk to your vet. I think you need to go one further, though, since most veterinarians know little about herbs – find a veterinarian who has a special interest in herbal medicine. Not only are they more aware of interactions and toxicity, recent research and clinical experience, they also take great care to source their products from American companies, some of them organic, that employ knowledgeable formulators.

    About the PDR recommendation – that will not be helpful as it is for people only. Please see Veterinary Herbal Medicine (Elsevier, 2007). Disclaimer – I’m the first author on it – but it was written to collect the most comprehensive available information on herbs and their use in domestic animals. There are thousands of references, detailed information on over 100 herbs including known toxicity and interactions, species specific cautions, traditional ethnoveterinary uses and scientific support.

  6. Nancy:

    As the Pet Division Brand Manager at American BioSciences (a company that provides natural products for both pets and their human companions) I say THANK YOU for making this information available to your readers.

    It is true that more pet parents are turning to natural products but before they do — they need to take on the challenge of becoming the “expert” on their pet’s issues and available products (natural and prescription) in order to make the best decisions. Yes, I know that is a daunting task but it is absolutely necessary!

    May I make a few suggestions regarding a pet parent’s review of natural products…

    1. Absolutely use the ACCLAIM system to evaluate a company/product. If the information from a label or website is insufficient CALL THE COMPANY! (FYI: The labels on ABS pet products are currently in revision and will meet all the ACCLAIM requirements (and more) in the very near future.)

    2. There is an association called the NASC (National Animal Supplement Council) whose members strive to provide the best products possible AND must adhere to specific regulations that help insure quality. And, the labeling requirements meet the ACCLAIM system. (FYI: ABS is a member and is in the process of meeting all requirements)

    3. Please let me stress — if you (or your vet) have questions call the company! Use your radar — if they seem to be evasive please think twice!

    Thanks for this opportunity for me to put my two cents in!

  7. I have been giving vitamins to my dogs for years–since 1988–with wonderful results. But no herbs. What I give is vitamin C in the form of sodium ascorbate, B complex 100 timed release, extra virgin olive oil, natural vitamin E, Multidophilus Plus, and a dog multi-vitamin, currently Pet Tabs Plus.

    I got the dosage information from the book by Belfield and Zucker, “How to Have a Healthier Dog.” Giving the dosages as indicated in the book have done really great things for my dogs. But herbs, no, I don’t think I would do that.

    —Kathy Diamond Davis, author, “Therapy Dogs: Training Your Dog to Reach Others”

  8. Dear Dr. Kay:
    Thanks for yet another insightful article and for bringing yet another important issue to people’s attention.

    I’m not sure where Dr. Byard got his information, but it may well have been from FDA reports as they started investigating chinese patent medicines about 20 years ago and continue to do so. The FDA started to release their findings back in the 90’s which is when we acupuncturists/herbalists first found out that there were unlabeled medications as well as heavy metals and other toxins in many patents made in China. This was not always the case with herbs made in China and hopefully, it will be remedied at some point.

    At that point, reputable practitioners stopped buying any formulas that were made in China and started to buy them from companies outside of China. Many great and reputable companies exist who use GMP (good manufacturing process) in the US, UK, Europe, & Taiwan (even though it is “in” China). Some companies in China continue to add unlabeled drugs to their formulas & do not test for purity. Additionally, they use their worst quality herbs for patents, in the same way a butcher would use their worst quality meat for sausage. Fortunately for us, they export their best quality herbs to the companies outside China who then sell them as raw herbs or make pill or granule/capsule formulas.

    The better companies outside of China use GMP & test each batch of herbs microscopically to identify that they are the herbs they are supposed to be, and also test for pesticide or toxic residue. This is why their formulas cost more than the ones made in China (better quality herbs and continuous testing). I know some of the people who run these companies & they are leaders in the field with great integrity. I have used their products for 20 years and have never had a patient have a troubling side effect (i treat the furless biped population). I have also used them for many years for my pets with great effect.

    In medicine, we know that anything that can help, can also hurt and this includes herbs although they are generally extremely safe and used globally more than medications. While there are sadly a handful of cases in humans of severe or fatal side-effects each year (most often when self-prescribed), we know that over 600,000 people go to the ER for side effects while using their medications as prescribed each year and over 100,000 tragically die (JAMA 279, 1998, pp 1200-1205). It’s obvious to all of us that greater monitoring is needed for everything we take as well as their possible interractions.

    Herbs should only be prescribed after a diagnosis (just like medications) and prescribing the right formula also reduces the risk of side-effects as several widely differing formulas are available for each problem and only proper training will guide the vet in choosing the right one. Learning the skills and information to make that diagnosis takes years (i.e., in California, acupuncturists receive 4 years of post-graduate training in herbology covering hundreds of single herbs and formulas). My suggestion is to see not just any veterinarian, as most … just like most MD’s, will not know about herbs. There are now well-trained holistic veterinarians that should be consulted, in my area (Sebastopol, CA) I refer people to Dr. Lisa Pesch who is very knowledgable and very good. The initial cost of consulting a holistic vet will likely be offset by more precise prescribing (i.e., fewer supplements) and there will be better results. Dietary recommendations will also be made and are essential. People would not prescribe medications for themselves or their pets and they really should get professional advice when using herbs as well.

    In terms of herb-drug interactions, there are some which is another reason to consult a professional. In general it is safest to dose herbs 1-2 hours away from medications (depending on the formula and the medication), and there are some contraindications (i.e., St. John’s Wort is contraindicated with SSRI’s as it potentiates their action). Again, another reason to see a holistic vet.

    There is a great saying from China about using conventional and complementary medicine together, they say that to use just one or the other is like walking on one leg. They both have a place, and many of my patients use both with no problems. . I find herbs incredibly effective in my practice and am able to treat people with certain problems (i.e., menopause, insomnia) with herbs alone. But again, it takes years to learn Traditional Asian Medical theory & now that we have holistic veterinarians in many communities, it only makes sense to have them oversee your pet’s care.

    Again, thank you very much for bringing this to people’s attention. Also, for anyone who can’t afford to buy a PDR, there is a lot of free information on many herbs available at as well as

    Your fan,
    Elisabeth Sherman, L.Ac.

  9. My Kami is taking Shen Calmer which is supposed to help with her doggy alzheimers & vestibular symptoms. But she’s also supposed to take Tramadol as needed for arthritis. I’m afraid of serotonin syndrome but my vet (who gave me the Shen Calmer & directions for Tramadol) says it shouldn’t be a problem. Kami’s going to a teaching hospital on Monday for a neurology assessment. They’ll want to anesthetize her, so I’ll tell them about the Shen Calmer for sure. (It doesn’t have St. Johns Wort in it, fortunately)

    Through my own research I found that my previous vet had prescribed a rather high starting dose of Tramadol. I switched to a human pharmacy and the label says “may cause dizziness.” I don’t think it actually is the cause of her circling & drunken gait, but I wish the vet who’d prescribed it would have told me what the potential side effects are. He also didn’t tell me about withdrawal symptoms. (This is the same vet that gave me a 21-50 lb dose of Advantix for a 17-20 lb dog)

    Whenever I get a new prescription for myself I read the patient insert & look it up online if I don’t get an insert. For some reason I’ve never done that with veterinary prescriptions. From now on I will always do that.