Herbal medicines: 4 problems you should know

Herbal medicines generally refer to medicines that include herbs, herbal substance, herbal preparations and finished herbal (including packaged) products that contain whole plants, parts of plants such as leaves, barks, roots and flowers or other plant materials as active ingredients.

Herbal medicines are viewed by many people as ‘natural’ and therefore must be safe. This assumption has led to an increase in the numbers of people taking it without considering its potential dangers in the same way they would be if they were conventional medicines. Researchers who conducted a study that accessed Herbal medicine use among residents in Lagos, Nigeria concluded that herbal medicine was popular among the studied population and also that the people did not know about the potential toxicity, interactions and adverse effects of herbal medicines.

herbal medicines tips
herbal medicines/Pixabay

Some herbal medicines and their uses


Salicylic acid is a key component of an herbal extract found in the bark of the willow tree. It reacts with acetic acid to form Aspirin, acetylsalicylic acid (ASA). Aspirin is used to relief pain and also to prevent blood clots. You can read more about the history of aspirin here.

weeping willow tree
weeping willow tree-pixabay


Digoxin (a form of digitalis) is used to treat irregular heartbeat. Digitals is derived from Foxglove (Digitalis purpurea). It works by slowing down heartrate and increasing the intensity of heart muscle contractions. Only tiny doses are effective which means it is easy to overdose on it. In fact, digitalis has been used as a poison for centuries.

Foxglove Digitalis purpurea
Foxglove (Digitalis purpurea)-pixabay

Morphine and codeine

Morphine and codeine are opiates found naturally in Opium Poppy (Papaver somniferum). codeine is converted to morphine in the body. There are used for pain relief and illegal recreational drugs. When the fleshy seed pod of the opium poppy is cut open, the active ingredients can be retrieved They are very addictive, and overdose could be fatal.

Papaver somniferum the opium poppy
Papaver somniferum (the opium poppy)-Pixabay

Artemisinin-based antimalarial medicines

Artemisinin-based medicines are derived from Artemisia annua (a Chinese medicinal herb). It is used to treat malaria. It is also referred to as sweet sagewort, sweet wormwood, sweet annie,  annual mugwort and annual wormwood.

artemisia annua
artemisia annua-Pixabay

Atropine and scopalamine

Atropine and scopolamine are present in the berries,  leaves and roots of Atropa belladonna. It is known to be extremely toxic. However, despite its toxicity, it has some medicinal benefit. Atropine is used for relaxing muscle spasms and regulating the heart rate. It is also used for dilating the pupils during an eye exam. Scopolamine is used for reducing body secretions and for treatment of motion sickness.

Atropa belladonna
Atropa belladonna

St John’s wort

St John’s wort (Hypericum perforatum) is a herbal medicine that has been used to treat mental health problems for centuries. hundreds of years to treat mental health problems. It can be used to treat mild to moderate depression, mild anxiety, and sleep problems. It interacts with a lot of medications.

st johns wort interactions
st johns wort/pixabay

Examples of cases where herbal medicines have caused problems


There was a case of a couple who presented to the emergency room with symptoms of digitalis poisoning from accidental foxglove ingestion. According to the wife, they had eaten a leafy green plant that tasted bitter the same day she started having the symptoms.  Read about the accidental foxglove ingestion here.

Artemisia annua

A man presented to the emergency department with malaise, abdominal discomfort, yellow stool, jaundice, and bile in urine. He has also lost weight. He was later diagnosed with severe acute cholestatic hepatitis (liver disease). He had just returned from Ethiopia where he consumed 1.25 g of Artemisia annua powder-tea every day to prevent malaria (Note that while Artemesia annua is recommended for treatment of malaria, it is not recommended for prevention). Read more about this case here.

Atropa belladonna

An eleven-year-old girl who was taking Rifampicin and Isoniazid for treating tuberculosis developed the side effect jaundice. She was then given Atropa Belladona by a herbalist to treat jaundice. She presented with dry mouth, uncontrollable vomiting incoherent speech, confusion, visual disturbances, hearing and visual hallucinations an nd was unable to recognise family members. She was diagnosed with Atropa Belladonna poisoning. Read the full story here.


Many herbal medicines including ginseng, aloe vera, green tea, Ginkgo Biloba, can interact with conventional medicines and lead to serious adverse drug reactions.

Patients tend not to tell their doctors that they are taking herbal remedies, either because they believe they are ‘natural’ and therefore, safe and do not interact harmfully with prescribed medications or because they are scared their doctors won’t approve of it and told to stop them. However not disclosing that you are taking herbal remedies to your doctors might be a fatal omission. This is because herbal medicines can interact with prescribed medicines.

Herbal medicines interaction with prescribed medicines

Taking herbal remedies with prescribed medicines can lead to adverse drug reactions due to herb-drug interactions. The interaction that occurs between herbal medicines and prescribed regular medication can be either because they inhibit (slows), or induce (stimulate) the liver converting/metabolizing enzyme (cytochrome P450 enzymes) or because the herbal products themselves produce the same effect as the normally prescribed medicine.

Inhibiting or Inducing Liver converting enzyme

They inhibit (slows), or induce (stimulate) the liver converting/metabolizing enzyme (cytochrome P450 enzymes). This is an enzyme that is responsible for converting/metabolizing or breaking down a lot of medications. After conversion/metabolism it exerts its effect and then gets cleared out of the body. Some medications including herbal medicines can slow down or stimulates for this enzyme.

When you take your prescribed medication with herbal medicine that stimulates this enzyme, the amount of prescribed medication may be reduced in the body and lead to an underdose and ineffective treatment. When you take your prescribed medication with herbal medicine that slows down this enzyme, the amount of prescribed medicine may increase in the body and lead to an overdose.

St John’s wort when taken together with other antidepressants like citalopram, duloxetine, fluoxetine can lead to serotonin syndrome. For instance, you buy St John’s wort to help with depression and then later see a Psychiatrist, if you do not tell the Psychiatrist about St Johns wort, you may be prescribed an antidepressant that interacts with st johns wort and increases your chances of getting serotonin syndrome which can be fatal.

Grapefruit juice contains a class of chemicals known to slow down CYP3A4 enzyme  (a subset of the liver converting/metabolizing enzyme cytochrome P450 enzymes), This leads to a slower-than-normal metabolism and, therefore, a higher drug concentration of the prescribed medication in the blood. Grapefruit juice interacts with calcium channel antagonists (Amlodipine), statins (Atorvastatin), angiotensin receptor blocker (irbesartan) etc.

Grapefruit juice interacts with a lot of medications

Produce the same effect

The herbal products themselves produce the same effect as the normally prescribed medicine. When you take your prescribed medication with a herbal product that produces the same effects, you may develop adverse effects. For example, Dr Chibuike shared with us how he had a man brought to him because he was having unprovoked bleeding from multiple sites even though he was a relatively healthy man. Blood was found in his urine and was bleeding from his nose and gums.

While having his history done, it was found that he had recently started taking a blood thinning medication called clopidogrel which was prescribed by his doctor. He was also taking five different herbal remedies which were mostly teas. Four out of the five remedies had blood thinning properties.

While taking clopidogrel carries its own bleeding risk, it was highly likely that the bleeding, in this case, was caused by the synergistic effect of the four herbal remedies plus clopidogrel. This is why it is important to tell your doctor about any medication you are taking including vitamins, over the counter medication, and herbal medicines.

Garlic for example inhibits (slows down) platelet aggregation hence can lead to increased bleeding risks when combined with other prescribed medications that can have the risk of bleeding like warfarin, aspirin and clopidogrel.

garlic inhibits platelet aggregation
Garlic inhibits platelet aggregation

4 problems with herbal medicines in Nigeria

The problems with herbal medicines in Nigerian are mainly due to the indiscriminate, non-regulated, irresponsible and non-standardization way it is used in Nigeria.

The overall quality, safety, and efficacy of herbal medicines, the conditions there were manufactured, preserved, and dosed are also unknown and can lead to problems. As there is a lack of regulation and monitoring of herbal medicines in Nigeria the extent to which they have caused to illness and death is not known.

1. Lack of clinical trial to prove effectiveness and safety.

A drug should only be used only when it is going to benefit a patient. This benefit is measured by the efficacy, safety, and the effectiveness of the drug. Conventional medicine goes through clinical trials to prove they are effective and safe. Herbal medicines however do not go through clinical trials.

  • Efficacy is the drug’s ability to produce the desired effect for example to lower blood sugar.
  • Safety is the chances of causing adverse effects.
  • Effectiveness is a measure of how well the drug works in a real scenario.

What are Clinical Trials?

Clinical trials are performed to collect data about the safety and efficacy of an intending new drug. There are several stages/phases of clinical trials course before a drug can be approved for use. Not all intending drugs gets approved.

Human Clinical Trial Phases

Phase I 
  • Evaluates the safety of the intending drug.
  • Lasts several months.
  • Healthy volunteers (20 to 100).
  • Aims to determine the effects of the drug on humans by assessing how it is absorbed, distributed, metabolized, and excreted.
  • Investigates the side effects of the drug at different doses.
Phase II 
  • Evaluates the efficacy of the intending drug.
  • Lasts between several months and two years.
  • Involves up to several hundred patients.
  • Randomized trials. One group receives the intending drug, while another group “control” receives a standard treatment or placebo.
  • Usually “blinded” studies which mean neither the trial participants nor the investigators know which group has received the intending drug.
Phase III
  • Evaluates the effectiveness of the intending drug.
  • Lasts several years.
  • Involves up to several hundred to several thousand patients.
  • Randomized trials.
  • Usually “blinded” studies.
  • Can request for approval for use and marketing after this phase is successfully complete.
Phase IV
  • Referred to as Post Marketing Surveillance Trials.
  • Performed after the drug has been approved for consumer use.
  • Compares drug to drug already previously used.
  • Monitors long term effectiveness of the drug.
  • The drug can be recalled (taken off-market) or condition of use placed on it.

2. Problems with Dosing

Dosing is especially important as some herbs can be very potent toxins which may be medicinal in tiny doses but toxic in large amount like in the case of digitalis above. When an appropriate dose is administered, the desired effect which alleviates symptoms and in some cases cure the disease with few side effects while at a toxic dose can cause harm to the body with adverse drug reactions.

The composition of raw herbs varies from batch to batch. This is because the amount of active ingredients may vary at different times of the year and in different climatic or geographical areas. Most herbal preparations in Nigeria do not have a standardised method of measuring the amount contained in the extracted material. This is a problem. For example, if a protocol for preparation calls for 3 leaves but each leaf in May contain 2mg but 6mg in December, a patient taking a herbal medicine from December would be taking three times the amount in May.

Liquid herbal medicines also have a particularly big problem with dosing because, in Nigeria, the dosing is something like take one glass three times a day. However, one glass in May could contain 2mg and another glass in December will contain 6mg. This difference in the concentration of one glass of liquid herbal medicines could be as a result of different dilutions used. In the manufacturing of conventional medications, a quantifying process e.g. spectrometry is used to measure the concentration of active ingredients in the medications and consequently correct dosed.

3. Non-Extraction of active ingredients

The herbal plant has many components in addition to the intended active ingredients. While one component can be used for therapeutic purposes, other components may be harmful to the patient. Some herbal products have been found to contain dangerous levels of arsenic, lead and mercury which can be poisonous.

While conventional medicines go the steps to separate plant components by High-Performance Liquid Chromatography (HPLC) and use only the active ingredients, most herbal preparations done by herbalists in Nigeria do not do this.

4. Produced in Unhygienic conditions

Most local herbal preparation are done in unhygienic conditions. This is concerning as people seek herbal remedies may already have their immune system compromised due to illness or infection.

The role of regulatory bodies in regulating herbal medicines in Nigeria

The National Agency for Food and Drug Administration and Control (NAFDAC) is the regulatory body responsible for food and drugs in Nigeria. The NAFDAC Act 1993, which was amended in 2005, prohibits the manufacturing, importation, exportation, distribution, advertisement or sale of any herbal medicines and related products unless it is has been appropriately registered and labelled by NAFDAC.

This regulation requires that herbal medicines and all related products should have labels that are accurate, informative, not promotional, misleading or provide any false claim.

Other information required about herbal medicines that should be on the package insert include accurate description of the product, its pharmacology (the study of drugs and how they affect the human body), indications (what it is used for), contraindications (situation in which a drug should not be used because it may be harmful to the person), warnings against misuse of the product, precautions, dosage and administration, side effect, adverse reactions including symptoms of overdosage and antidote, abuse and dependence, a description of how it is supplied, animal pharmacology, toxicology, clinical studies and how the medication should be stored.

Unfortunately, despite the detailed information stipulated by NAFDAC on herbal medicine package inserts, most herbal medicines available to patients in Nigeria do not meet this requirement. Medic drive is calling for the increased regulation of herbal medicines by NAFDAC.

Debunking the wonder-drug (one-drug does it all) Myth

I have seen some adverts of herbal preparations that claim to cure everything. I saw an advert where the vendor claimed his herbal product cures cancer, diabetes, tuberculosis, hypertension, depression, asthma, and any infection. There is no medication (conventional or herbal) that does it all.

How to take herbal medicines safely

  • Always let your doctor or health practitioner know about any herbal remedies you are taking.
  • Take herbal remedies that are registered with NAFDAC
  • Tell your doctor about any side effects you experience
  • Research about the herbal product you intend consuming.


Herbal products have a place in healthcare and are widely consumed all over the world. It is however important to know that they can cause side effects and interact with other medication. Herbal remedies are not regulated as much as conventional medicines which mean its safety and efficacy is not known. It is important that herbal remedies are consumed safely and that patient tells their doctor or health practitioner of any herbal remedies they are currently taking.

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