An Introduction to Herbal Medicine

Herbal medicines are those with active ingredients made from plant parts, such as leaves, roots or flowers. But being ‘natural’ doesn’t necessarily mean they’re safe for you to take.

Definition and Description of Herbal Medicinal Products

Often called herbal medicines, herbal remedies or herbal products and also known as phytomedicines and phytotherapeutic agents, herbal medicinal products (HMPs) have been defined as “any medicinal product, containing as active ingredients one or more herbal substances or one or more herbal preparations, or one or more such herbal substances in combination with one or more such herbal preparations”. Simply, this means that HMPs contain only herbs as active ingredients. Herbal medicines are complex mixtures which usually comprise at least 50 or so chemical constituents, although most contain many more. For the majority of these mixtures, the active constituents are, at present, unknown.

One of the basic tenets of herbal medicine is that interactions between different constituents occur, enhancing activity or reducing the likelihood of adverse effects. Such interactions may be additive, or truly synergistic in that compounds interact to produce an effect greater than the sum of the individual contribution of each. Although difficult to establish, true synergy between herbal constituents has been documented experimentally. However, if additive or synergistic interactions can occur, then it cannot be ruled out that negative interactions between herbal constituents may also occur.

In the United Kingdom, HMPs are generally considered by patients, the public, the media and many other groups to be “complementary” or “alternative” medicines. However, there is a view that HMPs with documented pharmacological activity and clinical efficacy lie alongside conventional medicines and some, such as senna preparations, are conventional medicines.

Use of herbal medicines

Most herbal medicines are purchased over the counter (OTC) for general well-being and for the prevention and treatment of common ailments. A survey involving 5,010 adults in England (response rate 59 percent) carried out in 1998 found that almost 20 percent had purchased OTC HMPs and 1 percent had consulted an herbalist in the previous year.3 Use of OTC HMPs by patients and the public is not limited to symptoms or conditions suitable for OTC treatment, or where there is supporting evidence. Individuals with serious chronic illnesses, including cancer, HIV/AIDS, multiple sclerosis, asthma and so on, use HMPs. In some cases, this may be as well as, or instead of, prescription medicines and this may have implications for pharmaceutical care. HMPs are also used by the elderly and pregnant or breastfeeding women and are administered by parents to children.

Individuals’ reasons for using HMPs include concern about the adverse effects of conventional drugs and the perception that MPs are “safe”. Related issues include non-professional sources of information and advice on HMPs, disclosure of use to health care professionals, and whether compliance with herbal medicines regimens is better than with conventional drug regimens.

The herbalist believes that the sum of the action of the whole plant is more balanced than that of any one of its main constituents. Where the action of the active component is very powerful, the other constituents within the plant will limit it; where the active constituent is less powerful, other constituents will increase its effectiveness, or ensure that it reaches the part of the body that requires treatment. Due to this, and also because herbal medicines consist of natural plant material and not a synthesized chemical, herbal remedies are less likely to cause unpleasant side effects than orthodox drugs. However, it should be borne in mind that plant remedies are very powerful and can be dangerous if prescribed dosages are exceeded. Some plant phytochemicals are toxic; pyrrolizidine alkaloids are hepatotoxic and large doses can cause convulsions and rapid death. These alkaloids can be found in plants like ragwort, bush teas from crotalaria species and comfrey (Symphytum officinale).

Herbal remedies should not be taken alongside conventional drugs or in pregnancy without consulting a qualified herbal practitioner or your doctor.

All herbal remedies are derived from plants. They can be given internally as:

• Tablets.
• Infusions: These are produced by pouring boiling water over leaves or flowers.
• Decoctions: These are produced by boiling barks or roots in water for a period of time.
• Tinctures: These are made by steeping plant parts in a mixture of alcohol and water.

Herbal medicines can also be administered externally, as ointments and poultices.

Medicinal plants can contain a variety of phytochemicals as well as minerals, vitamins and trace elements. Some of the phytochemicals are pharmacologically active and can exert a therapeutic action on the body. Plants with different properties are combined in a prescription tailored to the individual after taking a complete history and thorough physical examination from the patient to identify the problem. Herbal treatment is accompanied with advice on diet, exercise and any lifestyle changes that could possibly help to alleviate the condition.

Herbal medicines, just like conventional medicines, will have an effect on the body and can be potentially harmful if not used correctly.

They should, therefore, be used with the same care and respect as conventional medicines.

If you’re consulting your doctor or pharmacist about health matters, or are about to undergo surgery, always tell them about any herbal medicines you’re taking.

Potential issues with herbal medicines

If you’re taking or plan to take any herbal medicines, be aware of the following:

They may cause problems if you’re taking other medicines. They could result in reduced or enhanced effects of the medicine(s), including potential side effects.

You may experience a bad reaction or side effects after taking a herbal medicine.

Not all herbal medicines are regulated. Remedies specially prepared for individuals don’t need a license and those manufactured outside the UK may not be subject to regulation.

Evidence for the effectiveness of herbal medicines is generally very limited. Although some people find them helpful, in many cases their use tends to be based on traditional use rather than scientific research.

Certain groups of people should be particularly wary of taking herbal medicines.

Who should avoid herbal medicines?

Taking a herbal medicine may not be suitable for:

• people taking other medicines
• people with serious health conditions, such as liver or kidney disease
• people due to have surgery
• pregnant or breastfeeding women
• the elderly
• children – as with as with all medicines, herbal medicines should be kept out of sight and reach of children

Speak to your doctor or pharmacist for advice before trying a herbal medicine if you fall into one of these groups.

Herbal medicines and surgery

It’s important to tell your doctor if you take any herbal medicines before undergoing surgery.

This is because:

• some herbal medicines might interfere with anesthesia and other medicines used before, during or after procedures
• some herbal medicines may interfere with blood clotting and blood pressure, which may increase the risk of bleeding during or after surgery

Your doctor may, therefore, advise you to stop taking any herbal medicines during the weeks leading up to your operation.

What to look for when buying a herbal medicine

If you want to try a herbal medicine, look out for a traditional herbal registration (THR) marking on the product packaging.

This means the medicine complies with quality standards relating to safety and manufacturing, and it provides information about how and when to use it.

But you should be aware that:

• THR products are intended for conditions that can be self-medicated and don’t require medical supervision, such as coughs, colds or general aches and pains
• using THR products for more serious conditions could be harmful, especially if you delay seeking medical advice
• claims made for THR products are based on traditional usage and not on evidence of the product’s effectiveness
• a THR mark doesn’t mean the product is completely safe for everyone to take

You can find THR-registered products in your local health shop, pharmacy or supermarket.

Risks of buying herbal medicines online or by mail order

The risks of obtaining fake, substandard, unlicensed or contaminated medicines are increased by buying medicines online or by mail order.

Unlicensed herbal medicines manufactured outside the UK may not be subject to regulation. They may be copies of licensed medicines but made in unlicensed factories with no quality control.

Some websites may appear to be legitimate but are fronted by bogus doctors or pharmacists.

Herbal products sold online may also contain banned ingredients and toxic substances. You can find a list of banned and restricted herbal ingredients on the GOV.UK website.

Herbal slimming products and sexual health products, for example, are best avoided because they have been found to contain dangerous ingredients, including pharmaceutical ingredients, which aren’t stated on the label.

Reporting side effects

You can report any side effect or adverse reaction to a herbal medicine using the Yellow Card Scheme run by the Medicines and Healthcare products Regulatory Agency (MHRA).

This can help the MHRA identify new side effects or risks associated with medicines, including herbal remedies.

You should report adverse reactions or side effects if:

you suspect the side effect or adverse reaction was caused by a conventional medicine or herbal medicine you were taking the side effect occurs when you’re taking more than one medicine or herbal medicine

It’s important to include as much detail as possible, particularly any brand name or manufacturer’s details relating to the herbal medicine.

In the past, Yellow Card reports have been used to identify interactions between St John’s wort and other medicines, and to highlight the use of dangerous substances like mercury, lead and arsenic in unlicensed Ayurvedic and traditional Chinese medicines.