Kai Chen Ph.D. in
Chinese Medicine
TCM Dr. in British Columbia, Canada
205 Burnside Road East, Victoria, B.C. V9A 1A4 Canada
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TCM Dr. in British Columbia, Canada 205 Burnside Road East, Victoria, B.C. V9A 1A4 Canada |
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Safely Using TCM Herbs: Side-effects and
Precautions Although
most people believe that herbal remedies are relatively safe to use, some
are toxic or possess side-effects, especially when used incorrectly. Some
side-effects and toxicity of herbs and their preparations include and are not
limited to: 1.
Allergic reaction: urticaria, blisters and rashes frequently, shortness of
breath and asthma occasionally. Most symptoms are mild and self-limited, needing
no special treatment after discontinuation, but some herbal intravenous
injections may cause anaphylaxis, even death; 2.
Gastrointestinal symptoms: Nausea and vomiting often occur shortly after
administration. Stomach pain, which in some cases results in hemorrhage,
abdominal pain, and diarrhea, have occurred when certain herbs have been taken
on a short-term basis; 3.
Neurological symptoms: dizziness, headache, restlessness, tremor, numbness in
the extremities, depression, mania, and in rare cases, coma have been reported
in both short and long term use; 4.
Cardiovascular symptoms: palpitations, chest distension and pain, hypo or
hypertension, arrhythmias, heart failure even cardiac arrest have been seen in
both short term and chronic use; 5.
Renal symptoms: short and painful urination, scanty urine, anuria, bleeding in
the urine, edema, acute or chronic renal failure, have also been reported in
both short term and chronic use; 6.
Respiratory symptoms: cough and asthma, shortness of breath, dyspnea, difficult
breath, and even respiratory failure, have been seen in both short term and
chronic use. 7.
Other systems: fever, anemia, and changes in liver function, again in short or
long term use. Side-effects
and toxicity may occur in only one system, but can also involve several.
When side-effects and toxicity result, the herbs should be discontinued
immediately; in many cases no medical intervention is required, but in severe
cases, there may be severe permanent damage, even death. The following list includes commonly used TCM herbs with known side effects, as well as the most toxic herbs in the Chinese Pharmacopoeia. 1. Mu tong There
are eight different herbs that are commonly called “Mu tong”, of which three
are frequently used: Guan mu tong (Caulis Aristolochiae manshuriensis), Chuan mu
tong (Caulis Clematidis Armandii) and Mu tong (Akebia quinata).
All contain oleanolic acid and hederagenin; Guan mu tong, which is also
an herb of Aristolochia
genus, contains aristolochic acid (AA) A,
B, C and D, and aristolactam. Among
them, in almost all reports, Mu tong is Guan mu tong. Side-effects
and toxicity: The major toxic effect
of AA is to damage the kidney. There
are several reports of acute renal failure induced by one or several large doses
of Mu tong (50-175g),
with symptoms often occurring 1-4 hours after administration. The initial symptoms include digestive disorders, followed by
renal and cardiac toxicity, then death due to acute renal failure.
There are several cases reporting Mu tong toxicity when used in the
treatment of obesity and eczema. Often moderate doses of 15-30g where given on a
long-term basis and resulted in renal damage even terminal renal failure.
Therefore, the toxin accumulation could not be ruled out. Because
of the AA content, Guan mu tong toxicity is considered the greatest, followed by
Chuan Mu Tong, and finally Mu tong. These herbs also have potential carcinogenic
effects too. Precautions: In the Chinese Pharmacopoeia, the dosage of Mu tong (all three herbs mentioned) is 6-9g per dose. Just as the state of FDA “a product containing a small amount of AA could be used for years with no apparent adverse effects until serious, irreversible effects, such as renal dammed, has occurred” (FDA 2000:8), any kind of Guan mu tong, including raw herb and its products definitely should not be used. Even thought the toxicity and side-effects of the other two kinds of Mu tong require further study, both should not be used until further information is available. 2.
Fang Ji There
are two types: Han fang ji (Stephania tetrandra S. Moore), which is an herb
belonging to Menispermaceae, and Guang fang ji (Aristolochia fangchi), which is
an herb of Aristolochia
genus. They are different plants and the
chemical composition also different, the former main active component is
tetrandra, and the later contains AA. Side-effects
and toxicity:
Due to AA, the toxicity of Guang fang ji is virtually the same as
Guan mu tong. In one study, the
major active ingredient of Han Fang Ji, tetrandra, 15mg/Kg was given to rabbits
intravenously for 2 minutes. After 5-10 minutes 88.9% of the rabbits died; in
mice, the intravenous injection LD50 was 37.5 mg/Kg and
intra-abdominal injection LD50 was 280mg/Kg.
The toxicity of tetandra in humans remains unknown, thus further study is
required. Furthermore, there are
several reports where Han fang ji was used to control bodyweight and resulted in
kidney damage and even terminal renal failure, but it is generally believed that
it was mistakenly substituted with Guang fang ji. Precautions: Guang fang ji should not be used due to its AA content. The dose and administration period of Han fang ji also should be controlled. 3. Xi Xin (Herba Asari) This herb belongs to the Aristolochia genus. It mainly contains volatile oils, higenamine, amino acids, also AA, etc. Side-effects
and toxicity: Its toxicity, not only
related with AA but also some of its volatile oils, includes nausea, vomiting,
headache, dyspnea, fever, hypertension, spasm, convulsions, coma and respiratory
that may lead to death. Two of its
volatile oils, safrole and methyleugenol, inhibit the CNS respiratory center.
In recent years, its renal toxicity became more evident due to AA. Lab
studies also show that safrole is carcinogenic in mice. Precautions:Xi
Xin is traditionally known as a toxic herb; in all ancient TCM pharmacopoeias
the recommended dosage is not over 3g. Due
to its composition of AA, it should no be used anymore. Ma
dou ling (Fructus Aristolochiae) and Qing
mu xiang (Radix Aristolochiae also belong to Aristolochia genus
and contain AA, which should be not
used. 4.
Wu tou and Fu zi (Radix Aconiti Praeparata) There
are two herbs that have the name of Wu tou: Cao wu tou (Radix Aconiti
Kusnezoffii) and Chuan wu tou (Radix Aconiti), all belonging Ranunculaceae
genus. Side-effects
and toxicity: All of three have
toxicity, due to the constituent, aconitine.
Cao wu tou is considered the most toxic. The aconitine LD50 in
mice (oral administration, subcutaneous, intra-abdominal and intravenous
injection) is 1.8, 0.27-0.38, 0.3-0.38 and 0.12-0.27 mg/Kg respectively; the
fatal human oral dose is 3-5 mg. In
China, in all of herbs toxin and dead reports, they were one of the most commons.
For example, one review included 1241 herb toxin cases, in which 237 cases
caused by them. The
initial symptoms of CNS stimulation often appear 10-30 minutes after
administration. These include restlessness and headache.
After stimulation, there is CNS depression.
Symptoms include tongue, mouth, limbs numbness, spasms, followed by
digestive disorders, arrhythmias, dyspnea, respiratory and heart failure
leading in some cases to death. Precautions:
The
main reasons for toxicity are often due to (1) the use of non-prepared herbs and
(2) the herbs not decocted for a sufficient duration.
Decocting these herbs for over two hours decomposes aconitine,
decreasing the toxicity 100-1000 times. Other
reasons for toxicity include over-dose, or administration in wine (tinctures) as aconitine
is easily extracted by alcohol thus greatly increasing its concentration
compared to that from water extraction (decoction). The recommended dosage of
Chuan wu tou is 1.5-3g, Cao wu tou, 0.5-1.5g and Fu zi 3-6g in decoction.
When taken orally, the prepared herbs must be used and must be decocted
for a period not less than two hours in duration. Xue
shang yi zhi hao (Radix Aconiti Brachypodi) contains the same active ingredients
and toxin is the same. 5.
Cang er zi (Fructus Xanthii) Side-effects and toxicity: Its toxic components include the protein xanthostrumarin and carboxyatractyloside, which are water-soluble. The water extraction LD50 via intra-abdominal injection is 0.93g/Kg in mice. The administration of the moderate dose (30-45g) for greater than one month may cause toxicity in humans. Acute toxic symptoms include headache, dizziness, restlessness, possibly leading to seizures and coma. Significant liver damage may occur. Digestive symptoms, such as nausea and vomiting, diarrhea and abdominal pain, have also been reported. Large doses over 100g can cause acute and severe toxicity (total system failure) including hepatic encephalopathy leading to coma, respiratory, renal and heart failure, and death. Precautions:The recommended oral dose 6-9g in decoction; doses over 30g may cause toxicity. 6.
Lei gong teng (Radix Tripterygii Wilfordii) Its
pharmaceutical components include glycosides, alkaloids, terpines, etc.
As modern pharmaceutical research
has shown it to anti-inflammatory and an immunosupressant, it is widely used to
treat rheumatoid arthritis, systemic lupus erythematosis and other autoimmune
disorders. Side-effects
and toxicity: In mice,
the glycosides oral
LD50 is 159.7mg/Kg and via intra-abdominal injection, 93.99 mg/Kg.
Its long-term toxicity in humans is dose-related, depending on both the
dose and its duration of administration. Side-effects
in humans include digestive complaints, hematological checked, sex
hormone disorders, heart, liver and kidney damage.
One study reported 17 cases of renal damage induced by Leigongteng, 15 of
which were due to administration of one overdose; the other 2 due to
accumulation at routine dosing. Acute
toxicity often appeared at least two hours after administration, with digestive
symptoms occurring first, such as nausea, vomiting, diarrhea and abdominal pain.
The second day after the onset of symptoms, renal damage followed, accompanied
by heart, liver, and lung toxicity. Among the 15 cases of acute overdose, 6 were fatal.
In another report accumulated 330 cases of toxicity of which 57 were
fatal. Mild side-effects are
reversible upon discontinuation; severe cases are not. Precautions: Both the raw herb and extracted preparations should not be used in pregnancy, lactation, or in severe hepatic or renal failure. Renal, hepatic, and cardiac function as well as WBC should be monitored regularly. 7. Ma huang (Herba Ephedrae) In this genus, there are several kinds of Ma huang,
commonly used Cao ma huang (Ephedra sinica stapf.) and Mu zei ma huang (E.
equisetina Bge.), and both functions and toxin are the same. It China, it is
very commonly used to treat asthma, common cold, cough and Yang edema.
Its active components are ephedrine alkaloids, which also perhaps mildly
suppress the appetite via the CNS hunger center.
For this reason, it is mainly used in North America in an attempt to
control bodyweight. The amounts of ephedrine alkaloids are 0.481-2.47 % and
2.093-3.05% in Cao ma huang and Mu zei ma huang separately. Side
effects and toxicity: The
LD50 of the intra-abdominal injection of the raw herb water
extraction is 650mg/Kg in mice. In humans, toxic symptoms often occur 30 minutes
to 2 hours after administration. These often include CNS disorders, such as
headache, dizziness, tinnitus, irritability, and cardiovascular symptoms, such
as palpitations, angina, tachycardia, and hypertension, other symptoms include
facial flushing, sweating, nausea, vomiting, and difficult urination. Ephedra has also been
known to cause hyper or hypoglycemia. As
it stimulates the sympathetic nervous system, it will exacerbate hyperthyroidism
as well as narrow angle glaucoma. Precautions: The FDA (1997:6) recommends the intake of ephedrine alkaloids to be not more than 8 mg per dose to be repeated no sooner than 6 hours, or a total daily intake of not more than 24 mg. It should not be used for more than 7 consecutive days. This herb should not be used in patients with heart disease hypertension, hyperthyroidism, diabetics, and in narrow angle glaucoma—these are contraindications listed on all cough/cold drugs containing ephedrine, pseudoephedrine and related sympathomimetic. 8. Ma qian zi (Semen Strychni) Its active components are alkaloids, mainly strychnine (50%), and brucine. Side-effects and toxicity: Its toxicity is similar to that of strychnine, mainly stimulating medullary bulb. Its effective dose is also close the toxic dose, the LD50 doses of strychnine, brucine and raw herb seed are 3.27, 233 and 234.5 mg/Kg via stomach in mice, and the adult fatal dose of strychnine is 60-80 mg; one fatal case was caused by the ingestion of 7 pieces of its seed. Initial toxic symptoms include headache, restlessness, muscle spasm and pain, dyspnea, followed by titanic convulsion and myoclonic paralysis of the diaphragm leading to breath cessation at the maximum inhalation phase. The main cause of death is respiratory failure. Precautions: The recommended dose is 0.3 to 0.6 g in decoction. It is recommended that prepared Ma qian zi be used as this, in many cases, decreases toxicity. 9.
Ren shen (Rx Panax ginseng) and Xi yang shen (Rx Panacis quinquefolii) These two types of ginseng are listed together as the active ingredients, mainly ginsenosides, are the same hence is the toxicity. As many people consider it a panacea, it is often abused or used incorrectly. Side-effects and toxicity: Because ginsengs may decrease platelet aggregation, bleeding time may be impaired. For this reason, these herbs should be avoided in patients taking aspirin, nonsteroidal antiinflammatory drugs, and, especially, anticoagulants. As bleeding time is increased they should also not be administered in the preoperative period. Ginsengs can also alter digoxin blood level tests. Other adverse reactions include headaches, tremors, nervousness, and insomnia. Ginsengs should be avoided in people with manic disorders and psychosis. If used for the control of blood sugar in type II diabetes, the patient’s physician should be notified, as a decrease in medication may be required. Precautions: Ginsengs should not be used in the patient populations listed above. 10. Yin
xing (Semen Ginkgo bilogae) Its
nut, Bai guo (Semen Ginkgo), is used most often traditionally, however the leaf,
Yin xing ye (Folium Gingkgo) is used more commonly in modern practice.
The
nut contains ginkgolic acid, hydroginkgolic acid, ginkgolinic acid and bilobol,
as well as small amount of cyanogenetic glycoside.
The leaf contains ginkgotin, isoginkgotin and bilobetin. Side-effects
and toxicity: Because raw leaf can cause nausea and vomiting, it is commonly used in
extractions where mild stomach upset and headache have been reported.
The nut is more toxic, including digestive symptoms, such as nausea,
vomiting and abdomen pain, incontinence of stools and urine, CNS disorders, such
as dulled reaction, spasms, convulsions, and coma; dyspnea and death due to
heart and respiratory failure may also occur.
Precautions:
As
the leaf has blood-thinning properties, it should not be taken with aspirin,
nonsteroidal antiinflammatory drugs and anticoagulants. The leaf should also be
avoided in patients with epilepsy, or in patients taking drugs that lower the
seizure threshold, such as antidepressants. 11.
Shan dou gen Shan
dou gen includes several unrelated herbs, the most commonly used are Guang dou
gen (Radix Sophorae Tonkinensis) and Bei dou gen (Rhizoma Menispermi), their
major active components are alkaloids that possess antiviral and antibacterial
activity. Side-effects
and toxicity:
Traditionally Shan dou gen was considered to be rather safe, but recently
more cases of toxicity have been reported, mainly concerning Guang dou gen.
Adverse reactions include nausea, vomiting, abdominal pain, dizziness,
muscle weakness, tremor, palpitations and hypotension. In severe cases, coma,
cardiac and respiratory failure can occur, the latter being the major cause of
death. Furthermore, toxicity in children is often more severe than that in
adults. One report showed Shan dou gen causes irreversible CNS damage in
children. The reported minimum dose causing death in adults is 100g and in
children, 60g. Precautions:
The recommended adult dose of Guang dou gen is 3-9g in decoction, as the
toxicity of Bei dou gen is much weaker, the recommended adult dose is 6-9g; both
dosages should be decreased in children. 12.
Ai ye (Folium Artemisiae Argyi) It
contains 0.2-0.5% volatile oils, which are the main active components. Side-effects
and toxicity: Its
LD50 of the water extraction when injected intra-abdominally is
23g/Kg in mice. If taken orally at
a dosage of 10-15g common toxic symptoms include thirst, dry mouth, nausea,
vomiting, abdominal discomfort, diarrhea and dizziness, which are self-limiting
in nature. If doses greater than
30g are, the toxic effects are often significant.
After administration, the initial symptoms may appear, include sudden and
severe abdominal pain, vomiting, palpitations, which are then followed by renal,
hepatic and potentially permanent CNS damage. Precautions:
As
Ai ye is frequently used in pregnant women, the recommended dose must be
strictly adhered to. 13.
Bai tou weng (Radix Pulsatillae) and Wei ling xian (Radix Clematidis) Both
are the herbs of Ranunculaceae genus. In
both herbs, the main active components are Protoanemonin and Anemonin.
Wei ling xian is not herb belonging to Aristolochia
genus, but FDA listed it
containing AA too. Side-effects
and toxicity: The
fresh un-dried herbs contain a higher concentration of Protoanemonin, which is
an irritant to skin and mucous membranes, leading to dermatitis; high doses have
been known to cause gastrointestinal tract and internal organ hemorrhaging which
may be fatal. It is likely
the concentration of Protoanemonin is decreased if decoction time longer or if
aged dry herbs are used as this causes Protoanemonin to be broken down into
Anemonin. Because the old dry herbs
are commonly used, the toxin cases are reported few.
If Wei ling xin contains AA, it also can cause renal damage, but until
now there was no such report. Precautions:
The fresh herb should be cooked longer at least 45
minutes, if it is to be used at all. 14. Ban xia (Rhizoma Pinelliae) and Tian nan xing (Rhizoma Arisaematis) Both are
herbs of Araceae. The alkaloids, present in both compounds are the main active
and toxic components. Side-effects
and toxicity: The toxicity of both
herbs is directly related to their method of preparation and decoction.
The dry herbs are irritating to skin and mucous membranes. They also
exhibit CNS toxicity. The main symptoms include mouth and digestive tract
erosion and swelling with local pain, heat and numbness.
Other symptoms include dizziness, muscle spasms, convulsions, dyspnea and
palpitations. In cases of severe
toxicity, death is often due to respiratory failure.
Precautions:
To decrease toxicity, prepared herbs should be used with a decoction time of not
less than 45 minutes to 1 hour. Traditionally
Sheng jiang (Rhizoma Zingiberis Recens) can relieve the toxicity of Ban xia, but
the researches did not proved it. 15.
Xing ren (Semen Armeniacae Amarum) and Tao ren (Semen Persicae) Both
are seeds of fruits in Rosaceae. Both
contain oils, amygdalin and emullsin. Side-effects
and toxicity: Amygdalin is the main toxic constituent, which can
be decomposed to hydrocyanic acid. Toxicity
is dose related; 55-60 pieces of Xing ren, containing approximately 1.8g of amygdalin,
is often the fatal dose in adults. Two
hours after administration, the first symptoms often appear, such as a bitter
taste in mouth accompanied with oversalivation, nausea, vomiting, abdominal
pain, diarrhea, headache, dizziness, palpitations, dyspnea, cyanosis, which may
lead to coma and death due to respiratory arrest. Precautions:
The
recommended adult doses of Tao ren and Xing ren are 6-12g in decoction.
16. Yang jin hua (Flos Daturae) and Tian xian zi (Semen Hyoscyami) Both are herbs of Solanaceae and have similar
functions and toxicity. Their
active components are alkaloids, including scopolamine, hyoscyamine and
atropine; therefore their pharmaceutical functions and toxicity are similar as
atropine. Side-effects and toxicity: Mild side-effects include thirst, dry mouth, constipation, mydriasis, inability to sweat, urinary hesitancy, slowed heart rate, palpitations, dry skin, hot sensations and dizziness; in severe cases, cardiac toxicity such as increased heart rate, AV block, arryrthmias, as well as CNS toxicity are seen where symptoms such as disorientation, psychosis, hallucinations, high fever, coma, and even death occur. Children and the elderly are more susceptible to these anticholinergic effects. It also is one of the herbs most commonly causing adverse reactions, for example one paper accumulated 2095 toxin cases caused by 19 individual herbs, in which 739 induced by it that was the most. Precautions:
The recommend dose of Yang jin hua is 0.3-0.6g, and
Tian xian zi 0.15-0.3g in decoction separately. Caution should be used in children, the elderly; also in
patients with cardiac dysfunction, an enlarged prostate, or narrow angle
glaucoma. 17.
Chuan lian zi (Fructus Toosendan) Its
main active and toxic component is toosendanin. Side-effects
and toxicity:
Large doses of toosendanin can cause internal organ hemorrhage and severe
hepatic toxicity. The reported
toxic dose of the herb ranges from 10-70 pieces.
Four to eight hours after administration, toxic symptoms appear,
including numbness in the extremities, paroxysmal spasm, dyspnea, hypotension,
hepatic damage, internal hemorrhage, and even death. Precautions:
It should be very careful to use it for children to kill parasites due to
its over-dosage. 18.
Guan zhong Under
this category, there are 31 different herbs in 5 genii, but the most
commonly used is Dong bei guan zhong (Rhizoma Dryopteridis Drypteris
Crassirhizoma Nakai). The
main active and toxic constituents are dryocrassin and filmarone.
Side-effects
and toxicity:
The oral LD50 of the water extraction and dryocrassin is 104.1g/Kg
and 640mg/Kg in mice respectively. Mild
toxic symptoms include headache, dizziness, nausea, vomiting and diarrhea.
Severe cases due to over dosage may result in permanent renal and hepatic
damage, coma, and even death due to respiratory and cardiac failure.
Toxicity is often are more significant in overweight patients, as lipids
promote its absorption. Guan Zhong
should not be used in pregnant women as it may cause miscarriage.
Precautions:
It
should not be given with a fatty meal and should never be used in
pregnant patients. 19.
Huang yao zi (Rhizoma Dioscoreae Bulbiferae) Saponins
are its main active and toxic components. Side-effects
and toxicity:
The saponin LD50 is 1.438g/Kg in mice.
It is irritating to the mouse gastrointestinal tract.
In humans, more than forty cases of the toxic hepatitis have been
reported; the majority of these patients were being treated for thyroid
disorders at a dose of 10-21g daily. Over dosage with Huang yao zi can cause
acute toxicity, including cardiac and respiratory failure, even death. Precautions:The hepatic functions should be tested regularly
and the patients with hepatic dysfunction might not be used. 20.
Gan cao (Radix Glycyrrhizae Uralensis) Its active components include glycyrrhizic acid, glycyrrhetic acid, liguiritin, and liquiritigenin. Side-effects
and toxicity: Its side-effects are due to its glucocorticoid and
mineralcorticoid activity. It can
cause sodium retention the body leading to edema and hypertension, as well as
other steroidal disorders such as adrenal and immune suppression, impaired wound
healing, masking of infection, hypokalemia, osteoporosis due to increased
calcium excretion, hyperglycemia, gastric irritation, gastrointestinal
ulceration, loss of muscle mass, buffalo hump, depression, mania, and psychosis,
etc. Precautions:
The low dosage should be used for a short duration
in patients with congestive heart failure, edema, hypertension, gastrointestinal
ulcers, active untreated infection, and steroid disorders.
In diabetics, blood sugar should be monitored regularly if given over
prolonged periods, especially at the higher end of the dosage range.
Corticosteroids cross the placenta and affect fetal development thus Gan
cao should only be used at the lowest dosage for a limited duration in pregnant
women. 21.
Ban mao (Mylabris) Its
main active and toxic constituent is Cantharidin.
Traditionally it is used externally to treat skin diseases; in modern
practice it is also used to treat cancer, hepatitis and cerebral stroke sequelae. Side-effects
and toxicity: The toxic dose is 0.6g,
and lethal dosage range 1.3-3g in human orally.
Toxicity often occurs 10 minutes to 2 hours, or 2 hours after oral and
external administration, respectively. Toxicity
related to oral administration includes a sensation of burning in the mouth,
which may lead to ulceration in digestive tract, and thirst. The more severe
toxic reaction that followed include nausea, vomiting severe abdominal pain,
diarrhea, bleeding in the stools, diarrhea, dyspnea, high fever, headache, renal
damage, shock and sudden death. External
administration may cause blistering and skin ulceration. Precautions: The oral dose is 0.03-0.06 g, prepared only in decoction. 22.
Chan su (Venenum Bufonis) Its
main active and toxic constituent is bufotoxin, which has a function is similar
to digitalis glycosides. Side-effects
and toxicity: Chan su, although it is used in patent preparations,
is traditionally known for its toxicity and is seldom used in decoctions.
Toxicity is often due to over dosage of the patents, such as Liu shen wan and
Hou zheng wan. After administration
1 and half to two hours, symptoms similar to digitalis toxicity appear, such as
nausea, which is often the first indicator of toxicity, anorexia, vomiting,
visual disturbances relating to colour vision, headache, weakness, psychosis,
arrythmias, slowing of heart rate, AV block, and asystole.
Severe cardiac damage is the major cause of death.
It has also been known to promote contraction of the uterus; therefore it
should not be used in pregnant women. One
paper accumulated 27 toxin cases induced by Liu shen wan, including one fatal. Precautions:
It should be used cautiously in patients with renal dysfunction, hypokalemia
(which may be a side-effect of certain diuretics and corticosteroids),
hypercalcemia, and hypomagnesemia, as these factors increase cardiotoxicity. It
should not be given to patients who are prescribed Digoxin®. 23. Quan xie (Buthus Martensi) and Wu gong (Scolopendra Subspinipes) Buthatoxin is the main active and toxic component of Quan xie. Wu Gong contains toxin-proteins, similar as hydroxylysine, taurine, and a histamine-like substance Side-effects and toxicity: The minimum intra-abdominal injection lethal dose of Buthatoxin is 0.07mg/Kg in rabbit and 0.5mg/Kg in mice. LD50 of Wu gong water solution with toxin proteins is 9.9g/Kg via stomach in mice. Reports of toxicity due to Quan xie decoctions are much fewer than Wu gong; perhaps Buthatoxin is destroyed by high temperature or by stomach acid. The Quan xie toxic dose is over 30g and Wu gong over 15g in decoction and the side-effects of both include dizziness, headache, nausea, vomiting, muscle spasm, and palpitations; In severe cases renal damage, coma, and death due to respiratory failure have been reported. Precautions: The decoction dose of Quan xie is 2-6g; Wu gong 1-3g. 25.
Gou wen (Herba Gelsemii Elegantis) It
is often used externally and the major constituents are Kouminicine, Koumine,
Kouminidine, and gelsemine. Side-effects
and toxicity: Most of components are
considered toxic, especially Kouminicine, whose rabbit minimum lethal dose is
0.8 mg/Kg; the raw herb, in humans is considered toxic at an oral dosage of
2-3g. Although this herb is intended for external use, most cases
of toxicity are due to internal administration; but in one case, 500g of Gao wen
was placed in bathwater. When used
internally, or when doses far larger than the recommended dose of 50g externally
are given, toxicity results in dyspnea, and respiratory arrest, the main
cause of death. Cardiac and renal
damage may also occur.
Precautions:
When
given orally, the effective dose is often equivalent to the toxic dose.
It should therefore, not be given internally.
When applied externally, its dosage should not exceed 50g.
Conclusion: Although
there are many cases of herbal toxicity reported in literatures, many of these
could be avoided if they were used correctly: 1.
Incorrect species chosen:
There are a number of herbs in the Chinese materia medica that have one
common name yet include many different herbs, even belong to a different genus. For
example, under the name Fang ji there are four different herbs, the two most
commonly used are from a different genus, Han fang ji is from Menispermaceae, and Guang fang ji from the
Aristolochia
genus, commonly substituted for each other and often the TCM practitioner is not
aware of which herb is being dispensed. FDA
is removing all herbs that contain AA, as well as those thought to be
contaminated or adulterated with AA. 2.
Over dosage: Most of the recommended herb doses
are considered safe, especially those for toxic herbs. For example, the recommend dose of Cao wu tou
is 0.5-1.5g in the Chinese Pharmacopoeia whereas the dose in most cases of
toxicity is much higher, often ten times higher.
Careful consideration of dosage reduction is necessary in children. One
report where 60 children were administered Shan dou gen to prevent influenza,
demonstrated significant side-effects, including permanent CNS damage.
This was due to misuse of the herb in dosages far too great for children.
3.
Administration of toxic herbs to pregnant and lactating women: It is prudent not to give any of
the above herbs to pregnant and lactating women, unless stated otherwise as the
risk to the fetus/baby may be considerable. 4.
Recommended duration of administration exceeded:
With each herb its suggested duration of administration is different;
generally according to TCM theory “any treatment should be stopped after the
illness is relieved”. No herb can be taken on an unlimited continual basis. For example, The TCM function of Mahuang is to smooth lung Qi
and disperse wind-cold, and often used to treat common cold, cough and asthma,
but in North America it is often used to treat obesity or decrease weight for
certain sports and is used for prolonged periods. The extended use of the herb, in conjunction with obesity
being a risk factor for hypertension, cardiovascular and other side-effects with
Ma huang are expected. 5.
Unacceptable Indications:
As was seen above in the case of Ma huang being used to control weight,
it is often used alone or with diuretic herbs that may disturb electrolyte
imbalance, predisposing the patient to cardiovascular toxicity.
Perhaps Ren Shen is most often abused, as it is often taken for prolonged
periods to increase energy and sexual potency.
This can be dangerous in hypertensive males as their blood pressure may
increase. If used appropriately under the supervision of a TCM practitioner,
these, amongst other adverse effects would not occur. 6.
Potential herb – drug interactions.
Herbs with the function of promoting blood circulation, such as Tao ren,
Hong hua, Dan shen, Chuan xiong, and other herbs, such as Ren shen and Da suan
can affect platelet function. If
those herbs are combined with aspirin, nonsteroidal anti-inflammatory drugs, or
anticoagulants, it potentially increases the tendency to bleed. Some herbs contain cardiac glycosides, such as Bei wu jia pi,
Fu shou cao and Jia zhu tao, and some are calcium containing bones and shells
found in Long gu, Mu li and Zhen zhu mu; if they are used with digitalis, the
toxicity of digitalis may increase. As
herb-drug interactions are not well-known, the relationship between herbs and
modern medications requires much more study. 7.
Not considering the risk versus benefit ratio:
When
dispensing any herb that is known to have toxicity, risk versus benefit should
be considered. The herb must have a
greater benefit to the patient to outweigh the risk of giving it to the patient.
There appears to be a lack of information regarding the incidence of
adverse events due to TCM herbal therapy as Mu tong, Fang ji and Xi xin have
been used for thousands of years in China, with a large population, and renal
toxicity was very few until recently. Many
possibilities exist. It could be
that the incidence of renal toxicity is very low, or that the non-traditional
use of these herbs is resulting in renal toxicity, or that they have been given
to patients with some pre-existing renal dysfunction, or had existing factors
predisposing them to renal failure, such as concomitant use of drugs that
potentially nephrotoxic—this includes prescription or over-the-counter, thus
readily available, non-steroidal anti-inflammatory drugs, acetaminophen,
penicillins, cephalosporins, sulfa
antibiotics, ACE inhibitors, and thiazide diuretics, to name a few. If the incidence of toxicity solely due to the aristolochic
acid component of these herbs is unknown, a meaningful risk versus benefit
decision cannot be made. Furthermore
there are plenty of drugs that are known to cause similar toxicity, but as the
incidence is deemed low, and through risk versus benefit evaluation, they still
remain on the market. A thorough
literature evaluation assessing the risk of AA toxicity is required.
Meanwhile, these herbs and others suspected to be adulterated with AA
would not be available for use. Generally
speaking, compared with western medications, TCM herbal remedies are still
rather safe, provided the practitioners thoroughly understand their functions,
toxicity, recommended dosages, and technique of preparation.
Copyright by Kai Chen Ph.D. in Chinese Medicine & Angela Berscheid, published in Chinese Journal of Integrative Medicine 2003-2004
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