What I wish everyone knew before self-supplementing with herbs

Spoiler alert: herbs are not harmless

Nov 20, 2025

For many people, herbs evoke a sense of softness and simplicity. They are familiar little plants we can pick up at a market, steep into a cup, or blend into a routine without much thought. The word “natural” evokes feelings of safety and gentleness, making herbs feel approachable and low-risk. It’s an appealing story, one we’ve collectively embraced. But the real story is far more interesting and far more powerful.

Because herbs work.

And because they work, they can also work against you in harmful ways. This is the part the wellness world sometimes skips. Herbal medicine is more than folk magic; it is biochemistry. Plants affect the same pathways as medications, influencing enzymes, neurotransmitters, immune signals, inflammatory cascades, and even mitochondrial behavior. If you’ve read my pieces on the Cell Danger Response or Gut Health + Chronic Disease, you already know how sensitive these systems are.

So when herbs are self-prescribed out of context, especially when taking medications, tiny physiological experiments are run on our bodies. Sometimes they are harmless, sometimes incredibly helpful, and sometimes they can interfere with the very pathways that keep you alive and well.

Let’s walk through what this actually means, clinically, because herb-drug interactions are predictable, documented, and preventable when we treat herbs less like casual supplements.

St. John’s Wort: The most misunderstood herb in modern wellness

Hypericum perforatum is one of the most effective botanicals for mild to moderate depression. It is also among the most disruptive herbs in pharmacology. Not because it is dangerous, but because it strongly influences the enzymes that process medications.

Quick physiology refresher: When I talk about CYP(insert a letter and number combo) or cytochrome P450 here, I am talking about your liver’s detox machinery. Specifically, these are the enzymes responsible for breaking down medications, hormones, and plant compounds. Think of them like traffic lights in your internal chemistry. Some herbs speed up those lights, so medications like SSRIs or statins clear faster. Others slow them down, causing levels to accumulate. This is not obscure science; it’s the difference between a medication working, not working, or working too well.

St. John’s Wort induces CYP3A4 and p-glycoprotein, two of the busiest ‘traffic lights’ in your system. These pathways clear medications like:

antidepressants
birth control
immunosuppressants
benzodiazepines
chemotherapeutics
HIV medications
anticoagulants
antiepileptics

When those enzymes increase, medications drop below therapeutic levels. This is why St. John’s Wort can destabilize mood, interfere with contraception, or reduce the effectiveness of transplant drugs.

The herb isn’t the villain; it is the context that matters.

Ginkgo: Cognitive support with a physiological edge

Ginkgo biloba is marketed as a benign 'brain fog’ herb. But ginkgo’s real mechanism is its ability to modulate platelet-activating factor, which influences blood viscosity and microcirculation.

This is helpful in controlled settings, especially for older adults with cognitive changes. The part that gets lost is that if a client is also taking a blood thinner (including aspirin), they have now stacked mechanisms that can increase bleeding risk.

In practice, this matters most for older adults, people taking NSAIDs regularly, individuals with clotting disorders, and anyone scheduled for surgery. In an integrative clinic, this interaction is managed. In the Instagram wellness culture, it is not mentioned at all.

Licorice: A tea that acts like a hormone

Whole-root licorice Glycyrrhiza glabra is fantastic for ulcer repair and certain adrenal presentations. The issue is that the glycyrrhizin contained therein is a compound that increases cortisol activity by inhibiting 11β-hydroxysteroid dehydrogenase, shifting electrolyte balance by retaining sodium and wasting potassium.

Translated: licorice can raise blood pressure, trigger palpitations, cause swelling, and interfere with medications like diuretics or steroids.

Kava: For anxiety, with physiological considerations

Piper methysticum is one of the most effective herbs for anxiety and muscular tension. Used within traditional Pacific Island cultures, it was prepared intentionally and with deep cultural knowledge. Modern extraction methods, inconsistent sourcing, and genetic differences in metabolic enzymes all change how the body processes kavalactones. Add chronic stress or existing hepatic strain, and the margin for error narrows considerably. The rare cases of hepatotoxicity reported in the early 2000s emerged because the modern use of kava bore little resemblance to its traditional context.

Kava has an important place clinically. It is effective and powerful, but it requires discernment, appropriate duration, and a respect for dosage.

Berberine: A metabolic powerhouse with real consequences

Berberine is everywhere right now, marketed as a ‘natural Ozempic.’ But berberine does not work through one single pathway. It modifies:

bacterial species in the gut
carbohydrate metabolism
bile acid signaling
hepatic glucose production
AMPK activation

For a client not on medication, this can be incredibly helpful; for someone on metformin or insulin, however, this can cause hypoglycemia or alter how other drugs are absorbed.

Plants should never be used long-term, either. Some herbs have constituents the human body cannot safety metabolize or excrete in large, chronic amounts. For example, Pyrrolizidine alkaloids found in comfrey Symphytum spp., coltsfoot, and borage can damage hepatic blood vessels over time.

Why am I even writing about this?

In my experience, those with acute or chronic illness that disrupts their quality of life, are desperate to feel better. I learn about clients taking herbs because they are seeking relief from symptoms that conventional medicine has ignored. I understand why, and I support the instinct to do so; herbal medicine can be powerful. I also respect that herbs influence the same physiological pathways I write about in my articles on chronic disease, mitochondrial stress, and metabolic resistance.

Natural does not mean harmless or limitless. Natural means biologically active, which is why they work.

If you want to use herbs safely…

Start working alongside those who understand the interactions between herbs and your physiology. A trained integrative medicine practitioner, clinical herbalist, naturopathic doctor, or functional nutritionist helps you map out how your body processes plant compounds, how medications behave in your system, and what your physiology can and can’t tolerate.

The other part of the equation, the part that matters long-term, is you learning to ask better questions. You don’t need to be a biochemist you just need enough curiosity to understand the basics. This is exactly what I meant when I wrote Seeking Evidence in Herbal Medicine: Find a middle place where intuition, tradition, and physiology meet. It doesn’t have to be a one or the other approach, but a grounded understanding of how your body works paired with the instinct that draws you to plants in the first place.

Herbal medicine is about ownership. It is about understanding that your body is a living system with pathways, enzymes, signals, and checks and balances. Explore how your body works, or find someone who truly understands. Read the research. Ask your practitioner real questions. Knowledge creates agency, and with the right guidance, that agency becomes the foundation for real healing.

The Metabolic Health Edit

Discussion about this post

Ready for more?