Natural Doesn’t Always Mean Safe: The Hidden Dangers of Mixing Herbal Remedies with Modern Medicine.

Herbs contain active chemicals, and those chemicals can change how prescription drugs work. Some combinations make medicines less effective, some raise the risk of bleeding or serious side effects, and some strain the liver or kidneys. Always tell your doctor or pharmacist about every herbal product you take.

The “Natural Means Safe” Myth

Plants are the source of many modern medicines, which is exactly why they can be powerful. A herbal product is not harmless just because it comes from a plant. Its active compounds act on your body in the same way drugs do.

The problem is widespread. A 2022 Nigerian study reported by Al Jazeera found that 76.65 percent of participants had used herbal medicine, more than a third combined herbal and conventional treatments, and 82.44 percent did not inform their doctors. A separate study of diabetes patients in Lagos found that 206 (67.5%) did not disclose herbal use to their physician.

When your doctor doesn’t know what you’re taking, they cannot protect you from interactions.

How Herbs and Medicines Interact

An interaction happens when one substance changes how your body handles another. In broad terms, there are three patterns:

The medicine works less well. Some herbs speed up how fast your body clears a drug, so you may not get enough of it.
The effect becomes too strong. Two substances with similar actions can stack up, for example both thinning the blood or both causing drowsiness.
Direct harm. Some herbal products can damage organs on their own, especially when contaminated, wrongly dosed or used for long periods.

High-Risk Combinations Doctors Worry About

An important note on the evidence: the US National Institutes of Health points out that most herb-drug interactions identified in current sources are hypothetical, inferred from animal studies, cellular assays or other indirect means. But it adds that attention is needed for drugs with a narrow therapeutic index, such as cancer chemotherapy, warfarin and digoxin. A narrow therapeutic index means small changes in drug level can cause harm.

St. John’s wort (often used for low mood)

This is the best-documented problem herb. It has an overall high risk of drug interaction because it is a potent inducer of cytochrome P-450 enzymes and intestinal P-glycoprotein. Clinically significant interactions have been documented with cyclosporine, the antiretroviral indinavir, oral contraceptives, warfarin, digoxin and benzodiazepines, among others.

In practice, it speeds up the processes that change the drug into inactive substances, leading to lower drug levels in your body, and it can also cause harmful side effects with certain antidepressants. Combined with serotonin-acting drugs, it may lead to increased serotonin-related side effects that are potentially serious.

Ginkgo biloba and garlic supplements (bleeding risk)

NIH notes that taking ginkgo with warfarin is associated with increased risk of major bleeding compared with warfarin alone, and that using ginkgo with the HIV drug efavirenz is not recommended. A large US Veterans Administration analysis reportedly found a 38% increase in bleeding risk among patients on combined ginkgo and warfarin therapy. Garlic supplements also carry a bleeding concern: if you take an anticoagulant such as warfarin or need surgery, tell your healthcare provider if you take garlic dietary supplements.

Goldenseal, Asian ginseng and others

A recent scientific review concluded that goldenseal has a high herb-drug interaction risk with some medicines. Evidence for ginseng is mixed: studies on the effect of Asian ginseng on warfarin have had mixed results. An older review also cautions that many reports about ginkgo and ginseng are unsubstantiated, which is why a pharmacist’s review of your specific combination matters more than blanket rules.

Who is most at risk?

Anyone taking medicines where the dose must be precise, including:

Blood thinners (e.g. warfarin)
Heart medicines (e.g. digoxin)
Antiretroviral (HIV) medicines
Transplant anti-rejection drugs (e.g. cyclosporine)
Antidepressants and sedatives
Hormonal contraceptives
Diabetes and blood pressure medicines, where a change in effect can be dangerous

Pregnant or breastfeeding women, older adults, children and people with liver or kidney disease should be especially careful.

Beyond Interactions: Contamination, Dosing and Organ Damage

Interactions are only part of the picture. Herbal products also carry risks of their own:

Unknown dose. NAFDAC’s director general has warned that you don’t know the quantity you are supposed to take, and that after 14 days, a liquid preparation may start to develop bacteria that can make people sick.
Unregistered products. NAFDAC requires strict registration, testing and approval before herbal products can be sold or advertised, but says regulation has not kept pace with online commerce. Unverified products sold on social media are a growing concern.
Kidney and liver harm. A consultant nephrologist at University College Hospital, Ibadan, notes that herbal medicine continues to play a role in kidney disease cases in Nigeria, and he cited findings that about 46 percent of liver disease admissions in one Nigerian hospital involved herbs or roots.
Delayed treatment. Doctors report patients arriving at hospitals only when their conditions have significantly worsened, often after prolonged use of unverified treatments.

To be balanced: herbal medicine is part of Nigeria’s cultural heritage, and some products have scientific support. For example, a 2025 study found one local herbal mixture appeared safe for short-term use within tested dosage ranges, though the researchers called for more research on long-term effects and interactions. The point is not that all herbs are bad. It is that they must be used with information, not assumption.

8 Ways to Protect Yourself

Tell your doctor and pharmacist about everything you take, including teas, powders, roots, tonics and supplements. Treat herbal products as medicines.
Never stop a prescribed medicine on your own to replace it with an herbal remedy. Talk to your doctor first.
Check that the product is NAFDAC-registered and has a label, expiry date and manufacturer’s details. Avoid unlabeled concoctions.
Be cautious with online “miracle cures.” Confident claims on social media are not evidence.
Don’t assume more is better. Herbal dosing is often not standardized.
Watch for warning signs after starting any new product: unusual bruising or bleeding, yellowing of the eyes or skin, severe nausea, dark urine, rapid heartbeat, severe drowsiness or confusion. Seek medical help promptly.
Tell your surgeon or dentist about herbal products before any procedure, since some increase bleeding risk.
Take extra care with narrow-margin drugs such as blood thinners, heart, transplant and HIV medicines.

What to Ask Your Pharmacist

“Can I safely take [herbal product] with [my medicine]?”
“Does this affect how my medicine works or how long it lasts?”
“Are there warning signs I should watch for?”
“Is there a safer timing or alternative?”

Key Takeaways

“Natural” does not equal “safe.” Herbs contain active chemicals.
Some herbs, notably St. John’s wort, can weaken or dangerously intensify prescription drugs.
Many people never tell their doctors about herbal use, which hides the risk.
Unregistered and contaminated products add further danger.
The safest approach is open communication with a doctor or pharmacist, and verified, NAFDAC-registered products only.

Medical disclaimer: This article is for general information and does not replace professional medical advice. Do not start, stop or change any medicine based on this post. Consult a qualified healthcare provider about your situation.

Sources and further reading:

Over to you: Have you ever taken a herbal remedy alongside prescription medicine? Share your experience in the comments, and send this to someone who needs to read it.