Plants make a great many different chemical substances, mostly for the purposes of dissuading other living beings — fungi, insects and grazing animals — from consuming their
leaves, roots and fruits. These chemical substances are extraordinarily potent and diverse. Many taste disgusting, some are virulent poisons, and many will induce vomiting or
diarrhoea. None of these effects are surprising, given that substances such as these are produced to defend the plant. However, some of the chemical substances produced by
plants happen to have a beneficial drug-like action for people suffering from certain diseases. The effects of these substances are utilised in herbalism, sometimes known as
botanical medicine.
Over the millennia, herbalists have, through trial and error, tried to discover which plants have worthwhile effects. Indeed, this process probably began with our ape ancestors
– chimpanzees have been observed, when they are ill with parasitic infections, for example, to carefully select and eat particular leaves that have therapeutic effects. If
chimpanzees do this, it is a fair guess that the ape-like ancestors of human beings also did so.
At some point in human history – or prehistory – this use of wild plants became a systematic and specialised activity, now known as herbalism. No doubt the patients who went to
see herbalists (like patients visiting their doctors today) expected a cure for every ill, and no doubt herbalists felt bad about telling anyone that the problem was incurable.
At this point, quite a bit of wishful thinking and placebo effect (see p. 233) probably found its way into herbalism. The outcome was a mixed bag of herbal remedies – some that
worked, some that had no effect at all (apart from placebo effect), and a few that were positively toxic but whose bad effects escaped notice because of the seriousness of the
diseases being treated.
In recent times, a few herbal remedies have been put through rigorous scientific tests. As one might expect, some work and some don’t. More details of those that have been shown
to work
for allergies are given on p. 221. First, however, it is important to consider some of the misconceptions that surround herbal medicine, especially those relating to side
effects. These misconceptions are rooted in the basic philosophy of herbalism, so it is also important to look at this – and at other points of view about herbal treatment.
The ‘Mother Nature’ viewpoint
Some modern herbalists maintain that, for every human ill, nature has created a complete cure somewhere in the plant world – the job of herbalists is simply to identify that
cure. This belief is essentially religious and anthropocentric – that is, it assumes that the welfare of human beings is the central focus of the plant world. This goes against
common sense, because it suggests that plants produce a complex array of chemical components, not for their own benefit, but for ours.
A related idea, and one that is far more widely accepted, is that anything ‘natural’ must automatically be either harmless or positively beneficial to human beings. It’s a nice
idea, but nothing could be farther from the truth, as a quick survey of the plant world shows: hemlock is natural, belladonna is natural, and ricin –the most deadly poison known
– is natural. All come from plants.
Belladonna, of course, while being deadly poisonous in sufficient quantities, is also a medicinal plant. Its most significant ingredient, atropine, is a useful drug-like
substance in small amounts, and a poison in larger amounts. There is no sharp dividing line between these positive and negative aspects – even a small beneficial dose will have
some undesirable effects too.
In other words, herbs produce side effects, in just the same way that medicinal drugs do. This is almost inevitable – anything that alters body functions enough to act as a drug
will usually have some other unwanted effects.
In the case of herbal medicines, there is an added complication. Plants contain dozens, even hundreds, of different chemical substances, many of which have no benefits for
humans at all –they are just plain toxic. These plant toxins can produce various unpleasant effects of their own, to add to the side effects of the useful ingredients. So the
possibility of side effects is actually higher with herbal medicines than with medicinal drugs.
The side effects that occur with herbal treatment are sometimes very serious. Deaths have occurred in some cases, and in others, irreversible damage (e.g. to the liver) has been
done.
The ‘pure-is-best’ viewpoint
Many modern anti-allergy drugs were first obtained from plants –cromoglycate (see p. 148), for example, was originally extracted from the roots of an Egyptian plant called
ammivisnaga. The ground-up roots of this plant contain a great many other things besides cromoglycate, whereas the pharmaceutical preparations of cromoglycate are pure and of
known strength. This pure form of the drug has also been tested very thoroughly by pharmaceutical companies, in order to demonstrate its effectiveness, to identify the correct
dose, and to look for any serious side effects.
An advocate of scientific pharmacology would maintain that, with modern drugs, the patient is just taking the substance that works, not a mysterious cocktail of unknown plant
chemicals. In other words, you know what you are getting with a drug. You also know it has a good chance of working, and a relatively small chance of causing serious side
effects. With a herbal remedy, you are, to some extent, taking a leap in the dark.
Ephedra sinica, the herb known to the Chinese as Ma-huang, illustrates this point well. It contains a mixture of substances, including the powerful drug called ephedrine – it
was named after the plant. Ephedrine (see p. 156) can relieve the narrowing of the airways that occurs during an asthma attack. The presence of ephedrine gives Ma-huang the
ability to ease asthma, although it is more often recommended to help with weight loss. Unfortunately, over-use of Ma-huang can cause a spasmodic
contraction of the blood vessels in the brain, which can result in injury or death. Liver toxicity has also been recorded (see p. 220).
As for its anti-asthma ingredient, ephedrine, although this drug was once important in conventional asthma treatment, it is rarely prescribed now. Ephedrine has long been
superseded by other asthma-relievers that have a more precise effect on the airway muscles, and so produce fewer side effects.
The multiple-action viewpoint
Practitioners of Chinese herbal medicine, in preparing a treatment for atopic eczema, combine ten or more different herbs. There are some conditions, they say, that can be
treated with a single plant, but atopic eczema is not one of those. It requires a mixture – and none of the ingredients of that mixture, taken alone, has any effect. What they
are claiming is that the different drug-like substances in the herb mixture have a synergistic action, working together to treat the disease.
This same idea is sometimes applied to the many different chemical substances found in a single plant. Some herbalists argue that a herbal remedy is better than a modern drug
precisely because it contains a cocktail of different drug-like substances, the effect of one augmenting or balancing that of another.
There is no actual evidence to support this claim, but the fact that Chinese herbal mixtures have some success in treating difficult allergic diseases (see p. 221) demands that
Western doctors at least take the possibility of synergistic action seriously.
It might seem that this multiple-action viewpoint goes against the whole grain of Western scientific pharmacology – the ‘pure-isbest’ approach. However, Western medicine
frequently treats certain allergic diseases, such as asthma and chronic sinusitis, with a mixture of drugs.
Using herbal remedies safely
Always talk to your doctor before taking any herbal medicine, because of the risk of side effects, or interactions with any conventional drugs that you may be using.
If possible, get herbal treatment from someone who is also a doctor qualified in conventional medicine. Ideally, your herbalist should have access to laboratory facilities and
should order blood tests to monitor your reaction to the herb(s). Monitoring every 1-3 months is necessary with some herbs, to check for serious side effects such as toxicity to
the kidneys or liver (see p. 220).
Before buying herbal remedies from a health-food shop or via the Internet, contact the manufacturer and ask to see detailed reports of trials showing that the product is safe.
Think very carefully before taking a herb that has not The Chinese approach
One fundamental concept of Chinese medicine is that, rather than just matching the remedy to the disease, the treatment should also be based on the particular characteristics of
the patient concerned. This idea is shared by some other Eastern systems, such as Ayurvedic medicine.
Whereas a Western doctor might see you as a person with atopic eczema, a traditional Chinese doctor sees you as a person with a certain constitution which has got out of balance
and so produced symptoms in the skin. The constitution is usually the main focus of treatment, not the eczema. This approach means that different eczema patients get different
herb mixtures, and the same is true for other allergic diseases.
A traditional Chinese doctor will assess your constitution by taking your pulses (there are several in Chinese medicine, not just one), asking various questions, and studying
the appearance of your tongue – the same sort of diagnostic process that is used prior to acupuncture.
For the purposes of scientific investigations, where a uniform treatment is necessary, this traditional approach has been modified. A single standardised treatment is applied to
a particular disease – and the disease itself is diagnosed by Western medical criteria. Whether this is really comparable with traditional Chinese herbal medicine is open to
question. The same caveat applies to any off-the-peg Chinese herbal formula that is sold direct to the public, rather than being prescribed for an individual patient by a
trained practitioner.
The traditional philosophy of Chinese medicine makes for a lot of variability in herbal preparations. That is why categorical statements about side effects cannot be made –
while one mixture used for atopic eczema may contain a potentially toxic ingredient, another mixture may not.
undergone full safety trials. Find out all you can about the herb and discuss the matter with your doctor. Don’t fall for the ‘it must be safe – people have been taking it for
centuries’ argument. If a herb is only toxic to a minority of people, and its bad effects are slow to emerge (so people don’t get ill or die immediately after taking it for the
first time), its deadliness can escape notice for a very long time, perhaps indefinitely. In the case of pharmaceutical drugs, highly sophisticated information-gathering systems
are needed to ensure that such rare-and-slow effects are noticed (see p. 137) but nothing of the kind exists for herbal medicines.
Above all, do not neglect vital medical treatment (e.g. inhaled steroids for asthma) while trying out herbal remedies, as this can be dangerous. Always follow your doctor’s
advice about your drug treatment.
Risks to the liver
Among the side effects recorded for herbal treatment, liver damage is especially alarming. Deaths from liver failure have occurred with both Western and Chinese herbal
treatment. Liver toxicity has been recorded with the following herbal remedies: kava-kava, chaparral, germander, skullcap, mistletoe, senna, valerian root, jin bu huan, and
ma-huang or ephedra (Ephedra sinica). Some Chinese herbal teas prescribed for atopic eczema may also affect the liver, but this is not true of all eczema preparations – several
of the most widely used ones appear to be relatively safe.
Any medicinal herb might, in certain people, harm the liver. Should you feel ill while taking a herbal remedy, stop taking it immediately and see your doctor. The early symptoms
of liver toxicity, which you should watch out for, include jaundice (yellow
skin, and a yellowish tint to the whites of the eyes), pale faeces, dark urine, nausea and pain (usually in the region of the stomach).
Illicit steroids
Be very cautious indeed about pots of Chinese herbal cream sold for atopic eczema. Analysis of a selection of such creams found that two-thirds illicitly contained powerful
steroids – the very drugs that the people buying the creams were anxious to avoid. The dose of steroid in these herbal creams was alarmingly high, considering the purposes for
which some of them had been prescribed – such as use on the face of a baby. A substantial risk of serious side effects exists with these adulterated creams.
Sensitivity reactions to herbs
Like other natural products, herbs can provoke a true allergic reaction, and anyone with a tendency to allergies is at particular risk. Although any herb could, in theory, cause
such a reaction, some seem especially likely to do so:
• Echinacea, which sometimes causes anaphylaxis or an asthma attack. Severe reactions may occur even in people taking it for the first time, if they are already allergic
to other plants in the daisy family (such as ragweed or mugwort).
• Preparations containing royal jelly (obtained from honeybees) have sometimes caused near-fatal anaphylaxis in those allergic to pollen. Propolis, obtained from bees,
should also be treated with caution.
Contact dermatitis often occurs with tea tree oil and some other plant-derived substances applied to the skin (see p. 55).Herb—drug interactions
Using herbal remedies and taking medicinal drugs at the same time can be hazardous. These are the herbs that interact with anti-allergy drugs:
• aloe vera, buckthorn, cascara sagrada bark, ginseng, and senna pod or leaf can all interact with steroid tablets
• squill, lily of the valley and pheasant’s eye can increase the action and side effects of betamethasone (a steroid); rhubarb root also interacts with this drug
• kava-kava, if taken with cetirizine (an antihistamine) can increase side effects such as drowsiness and poor coordination; it may have the same effect with other
antihistamines.
Note that many drugs prescribed for conditions other than allergies may interact with herbs. Some of these interactions can be serious, so check with your doctor before taking
any herbal medicine.
Herbs that may work for allergies
Of the herbal treatments that have been tested, the following appear to have potential benefits for people with allergies:
• Chinese herbal teas for atopic eczema have shown good effects in scientific trials in Britain with both adults and children. Patients with widespread and persistent
eczema —which is particularly difficult to treat — were chosen for these trials. The puzzling thing is that when exactly the same herbal treatment was studied in Hong Kong, with
Chinese youngsters suffering from eczema, there was no improvement.
A combination of Chinese herbal medicine and acupuncture shows some limited benefits for hayfever patients (see p. 215). Pilot studies also suggest that a Chinese herbal
medicine formula may work for asthma.
More surprisingly, another mixture of herbs shows promise in reducing sensitivity for people with severe food allergy (so that there is less risk of fatal anaphylaxis from
accidentally eating the culprit food). Further research is needed to confirm these results. It is hoped that daily treatment for about six weeks will give 6-12 months’
protection.
If you are interested in trying Chinese herbal medicine, it is advisable to be monitored properly, as liver toxicity has sometimes occurred (see p. 220). See a reputable,
medically qualified practitioner, who can vouch for the contents of the herbal mixtures (imported ready-made mixes sometimes contain drugs such as steroids). Be warned that the
stuff tastes vile, and you have the daily chore of boiling it up before taking it. It can have a very mild laxative effect at first. Don’t use Chinese herbal creams unless they
are guaranteed steroid-free (see p. 220).
• Euphorbia acaulis has shown good effects with atopic eczema. Liquorice root may also help, but can have serious side effects if taken in large amounts.
• Evening primrose oil taken in capsule form, is known to calm inflammation, and might be helpful for atopic eczema. Don’t chew the capsules, as irritation of the throat
can occur. Epileptics should not take this oil.
• Ginkgo biloba seems to reduce the reaction to allergens. For those with asthma it may also calm inflammation in the airways.
• Ayurvedic medicine utilises two herbs, Coleus forskohN and Tylophora asthmatics, in the treatment of asthma. The former relaxes the airway muscles, in much the same way
as beta-2 reliever drugs, making the airways open up. The latter has more general benefits in asthma, but also some unpleasant side effects: it can cause nausea and soreness in
the mouth.
• Saiboku-to is a Japanese herbal treatment for asthma. Studies suggest that it may have beneficial effects on airway inflammation and may allow a reduction in the dose of
steroids needed.
• Butterbur has received a lot of publicity following a study which appeared to show that it was as good as the antihistamine cetirizine for hayfever However, the study
did not assess actual symptoms of hayfever, only the patients’ sense of wellbeing. Some preparations of this drug contain substances that could cause cancer, or carry a risk of
liver toxicity. Trials of butterbur for atopic eczema have shown no benefits.
• Perilla seed oil appears to damp down allergic responses, and may help some asthma sufferers.
Omega-3 oils
These oils are derived from certain types of fish. They are obviously not herbs, but they are often sold alongside herbal remedies in health-food shops, which is why they are
included here. Generally speaking, omega-3 oils have a calming effect on inflammation,
but occasionally they provoke skin rashes, and asthmatics who are sensitive to aspirin may find that they gradually get worse if they take omega-3 oils. This is probably due to
problems with the production of messenger chemicals called prostaglandins in people with aspirin sensitivity (see box on p. 151). The connection is that omega-3 oils can act as
raw materials for the manufacture of prostaglandins and leukotrienes. The details of how omega-3 oils cause trouble for aspirin-sensitive people are not yet understood.
