Herbal Remedies and Liver Damage: how to Prevent Harm
This month, news outlets in the UK shared the story of Lois Kinder, a 44 year old mother of two who had been taking two ashwagandha gummies a day for about a year, hoping to support her general wellbeing. She noticed her skin and eyes turning yellow, and three days later she was found collapsed at home. Doctors diagnosed acute liver failure, and although she received a successful liver transplant, complications during surgery left her with brain damage. Her husband has since spoken publicly so that other families might avoid what his has been through, and her doctors have said they believe the supplement was the cause.
My heart goes out to Lois, her husband, and their two children. Stories like this are rare and prompt an urgent and important reminder of something I discuss with patients every week. Herbal remedies are medicines. The same properties that allow a plant to have a real effect on the body are the properties that can cause real harm when a product is poorly made, combined with the wrong medication and/or used without guidance.
We do not know exactly why Lois became so unwell, and it would not be right to speculate about her individual case. What the research does show is that most herbal harm tends to trace back to a handful of common oversights. Here are three, along with a fourth safeguard worth knowing about for your safety.
Oversight #1: Assuming the Label Tells the Whole Story
The United States Drug Induced Liver Injury Network, known as DILIN, was established by the National Institutes of Health in 2003 to study liver injury caused by medications and supplements. When Dr. Victor Navarro and colleagues chemically analyzed supplements that had been collected from patients with liver injury, they found that roughly half of the products did not accurately match their labels, with the highest rates of mislabelling among weight loss, bodybuilding, and "energy" products. Some contained undeclared botanical ingredients, and some contained synthetic compounds such as illegally added anabolic steroids. A 2025 DILIN paper by Halegoua DeMarzio and colleagues in Drug Safety reinforced the point: inaccurate labels and undisclosed ingredients make it genuinely difficult to know what a person was actually exposed to.
Contamination is a separate concern. A well known study by Saper and colleagues, published in JAMA in 2008, found that about one in five Ayurvedic products purchased online contained detectable lead, mercury, or arsenic. These substances can cause harm on their own, regardless of the herb itself.
The practical takeaway is that quality is not a minor detail. In Canada, a Natural Product Number (NPN) from Health Canada is a good starting point, but it is worth going further and choosing brands that use independent third party testing to confirm identity, potency, and the absence of heavy metals, microbial contaminants, and adulterants before a product reaches the shelf. A product sold cheaply through social media, or sampled and resold by influencers, rarely offers that level of assurance.
Oversight #2: Overlooking how Herbs and Medications Interact
Many herbs are not dangerous on their own, yet they can change how the liver handles other medications. The liver relies on a family of enzymes, often called the cytochrome P450 system, to break down and clear drugs from the body. Some herbs slow these enzymes down. When that happens, a medication can build up to higher levels than intended, or the body can produce more of an intermediate byproduct, and in some cases it is that byproduct that injures the liver.
This matters most for medications with what is called a narrow therapeutic index, meaning the gap between an effective dose and a harmful one is small. Blood thinners such as warfarin, transplant medications such as tacrolimus, and certain antiseizure medications are common examples. A shift that would be meaningless for one drug can be serious for another.
This is where working with a licensed professional, rather than following advice from social media, makes a real difference. A naturopathic doctor can run a comprehensive interaction check on your specific combination of medications, supplements, and herbs, and consider your health history alongside it. No influencer can do that for you, however well intentioned they may be.
Oversight #3: using Herbs without Evidence Behind the Use
The evidence behind a remedy matters just as much as its quality. Reviews of ashwagandha, for example, have noted that its popularity has grown for many advertised uses that have not been confirmed in rigorous, well designed trials. Where studies do exist, they tend to be short, often around eight to twelve weeks, and they use specific standardized extracts at specific doses. A flavoured gummy taken indefinitely is not necessarily the same product, dose, or duration that was studied.
Working with someone trained in herbal medicine, such as a naturopathic doctor, means an herb is chosen because there is actual research supporting it for your situation, and it is used at the type of preparation, dose, and duration that research suggests is both safe and effective. Just as importantly, it means someone will tell you honestly when the evidence is thin or when an herb simply is not the right fit.
A Fourth Safeguard: Knowing your Liver Before you Begin
Even with a high quality product, no interactions, and good evidence, a small number of people experience an unpredictable reaction to an herb.
Because these reactions are hard to predict, it can be helpful to review relevant blood work, such as liver enzymes and bilirubin, before starting something new, particularly if you have a history of liver concerns or take other medications. Your naturopathic doctor can also help monitor these markers over time to confirm that you are tolerating a remedy well. It is also worth knowing the warning signs: yellowing of the skin or eyes, dark urine, pale stools, persistent itching, unusual fatigue, or nausea. If any of these appear while taking a supplement, stop it and seek medical care promptly.
Moving Forward with Care
Herbal medicine has a meaningful place in health care, and many people benefit from it safely every day. That safety is rarely an accident. It comes from choosing well tested products, checking for interactions, using herbs where the evidence supports them, and keeping an eye on how your body responds.
If you are considering an herbal remedy, especially while trying to conceive or during fertility treatment, speaking with a licensed, fertility focused clinician can help you understand what the research does and does not show for your situation, so you can make that decision with clarity and confidence.
This article is for educational purposes only and is not medical advice. It is not intended to diagnose, treat, or prevent any condition. Individual circumstances vary, and decisions about your care should be made with your own healthcare team. If you are trying to conceive or are currently in treatment, please speak with your physician or a licensed naturopathic doctor before starting, stopping, or combining any herbal remedy or medication.
About Dr. H. Singh, ND
Dr. H. Singh is a Fertility Naturopath based in Ottawa with over ten years of experience focusing exclusively on reproductive health.
He works with individuals and couples across Ontario and Quebec, supporting patients trying to conceive naturally or alongside treatments such as IUI and IVF.
Care focuses on evidence informed strategies to support egg quality, sperm health, hormonal balance, implantation, and early pregnancy.
