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Herbs with Drug Interactions - a Partial List
By popular request, here
is a partial list of herbs with drug interactions. It is by no means
complete! If you are taking medications, please check with your
prescribing physician before taking any supplements.
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|
Herb
- alphabetical by common name |
Possible
Drug Interaction |
Possible
Contraindications |
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Ashwaganda Withania somnifera
|
None known. (PPP, 601) May potentiate the effects of barbituates (Atal
and Schwarting). (BSH, 124) |
High dosages of alkaloids from Withania exhibit prolonged hypotensive,
bradycardiac and respiratory stimulant actions, may also have depressant
effect on higher cerebral centres; sedative effects have also been
demonstrated. (CAACH, 138) |
|
Bilberry Vaccinium
myrtillus |
None known. (HM, 18; TGHM,
88) Possible interaction with warfarin and antiplatelet drugs in very
high doses. (PPP, 301) |
Very high doses should be
used cautiously in patients with haemorrhagic disorders and in those
taking warfarin or antiplatelet drugs. (PPP, 301) |
|
Bladderwrack Fucus vesiculosus
|
None known. (HM, 213) Caution indicated within iodine-containing drugs.
(AEHD, 44) |
Therapeutic use is not recommended in hyperthyroidism, long-term
therapeutic use is not recommended. (BSH, 54) Contraindicated in
hyperthyroidism, cardiac problems. (BHC, 38) In rare cases allergic
reactions involving serious overall reactions may occur. (TGHM, 315)
|
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Black Cohosh
Cimicifuga racemosa |
Drugs for iron therapy
|
Inhibits iron absorption
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Bugleweed Lycopus virginicus
|
None known. (TGHM, 99) Do not take with thyroid medications. (BSH, TGHM,
99) |
Contraindicated in thyroid hypofunction, enlargement of the thyroid
without functional disorders. (TGHM, 99; BSH, 72) Administration of the
herb interferes with diagnostic procedures using radioactive isotopes. (TGHM,
99) |
Bupleurum
Bupleurum falcatum
|
The use of alcohol,
sedatives and other central nervous system depressants, in conjunction
with this herb, may cause synergistic sedative effects. (WHO, 73)
|
Bupleurum has a slight
sedative effect in some patients and may also increase bowel movements
and flatulence (wind). (CAACH, 23; WHO, 73, 74; PPP, 317) May cause
nausea and reflux in sensitive patients. (PPP, 317) |
Californian Poppy
Eschscholtzia californica |
May potentiate pharmaceutical MAO-inhibitors. (BSH, 49) |
This herb should be restricted in its application to experienced and
well-trained practitioners. (PPP, 232) There is a theoretically
increased risk of neurotoxicity and other adverse effects (although no
known incidence). (PPP, 233) The following cases should be approached
with caution: (1) concurrent prescription of powerful analgesics, (2)
pain in children, (3) neurological disease, (4) depression and
psychosis, (5) liver and kidney disease, and (6) history of allergic or
anaphylactic reactions. (PPP, 232) |
|
Cascara sagrada
Rhamnus purshiana |
Most intestinally absorbed
drugs; Thiazide-type diuretics |
Interferes with absorption
of the pharmaceutical agent; Raise blood pressure or deplete potassium
|
|
Chamomile Matricaria recutita
|
Drugs for iron therapy |
Inhibits iron absorption |
|
Coleus
Coleus forskohlii |
Forskolin has the ability to
potentiate many drugs. Use cautiously in patients taking prescribed
medication. (CAACH, 106) |
Contraindicated in
hypotension. (CAACH, 106) |
|
Dong Quai Angelica
sinensis |
Based on animal studies,
caution is advised for patients receiving chronic treatment with
anticoagulant drugs such as Coumadin (warfarin). (PPP, 352) |
Containdicated in bleeding
or very heavy menstruation, first trimester of pregnancy, acute viral
infections such as colds or influenza. (CAACH, 5-6; BSH, 11; PPP, 352)
Also contraindicated in diarrhea caused by weak digestion and in
haemorrhagic disease. (PPP, 352) Cardiovascular side effects include
excessive bleeding. (TCPHP, 290) Dong quai has two furanocoumarins (psoralen
and bergapten), which are photoreactive and have the potential to cause
severe photodermatitis. These furanocoumarins are also photocarcinogenic.
However, the risk of phototoxicity in humans from ingestion of Dong quai
has not been characterized. (TCPHP, 290-291) |
|
Echinacea
Echinacea purpurea |
None known. (HM, 97; TGHM,
123; WHO, 142; PPP, 360) |
Commission E cautioned that
the herb should not be used in systemic diseases such as tuberculosis,
leukosis, collagenosis, multiple sclerosis, AIDS, HIV infections, and
other autoimmune diseases (based on theoretical considerations and not
on any reports of adverse findings). (HM, 97; TGHM, 123; WHO, 141-142;
PPP, 359) Caution is advised for transplant patients taking
immunosuppressive drugs; short-term therapy is suggested. (PPP, 360)
Should not be administered to patients with known allergy to any plant
of Asteraceae (Compositae). (WHO, 142; PPP, 359; HM, 97) Allergic
concern based upon case reports. (TCPHP, 301; PPP, 359; WHO, 142) |
|
Evening Primrose Oil Oenothera biennis
|
Anticonvulsants and tricyclic antidepressants |
Lowers the seizure threshold, thus increasing drug dosage requirements |
|
Feverfew
Tanacetum parthenium |
Drugs for iron therapy;
Warfarin sodium, heparin, aspirin and other anticoagulants |
Inhibits iron absorption;
Augments the anticoagulant effect, thus altering clotting or bleeding
times |
Garlic
Allium sativum
|
Contains glucose. Use with
caution in patients taking anti-platelet drugs. Garlic’s antiplatelet
effect might be dangerous in patients taking warfarin or antiplatelet
agents such as aspirin, ticlopidine, clopidogrel, or dipyrida-mole. (TCPHP,
118; HM, 115; WHO, 25) |
Contraindication with
gastrointestinal disturbance; in rare instances, there may be changes to
the flora of the intestine, or allergic reactions. (TGHM, 134; HM, 145;
BSH, 6; BHC,106) May also cause heartburn, nausea, vomiting, and
diarrhea if taken on an empty stomach. (WHO, 26) HM suggests that
substantial amounts of garlic should not be consumed prior to surgery.
(HM, 145) May increase the risk of postoperative bleeding. (WHO, 25;
ESCOPM, 2; AEHD, 229) Allergic and dermatologic concern based upon case
reports. (AEHD, 229; WHO, 26; TCPHP, 116-117, 301) Hematologic concern
based upon in vitro data and case reports. (TCPHP, 301) |
|
Ginger Zingiber
officinale |
Contraindicated with
gallstones; consult a physician first. (HM, 156; BSH, 125; TGHM, 136)
May increase the chance of bleeding. (PPP, 401) Overdose may lead to a
blood-thinning effect and an increase in gastric secretory activity
leading to heartburn. (PPP, 401; ESCOPM, 1996, 1) Topical application
may cause contact dermatitis in sensitive patients. (PPP, 401); Warfarin
sodium, heparin, aspirin and other anticoagulants |
None known. (HM, 156, TGHM,
136) Caution should be used in patients taking anticoagulants and
antiplatelet drugs because of its potential antiplatelet effect. (TCPHP,
129; CAACH, 106) May increase the absorption of pharmaceutical drugs.
(PPP, 401) Caution indicated with patients taking blood-thinning drugs
such as warfarin, or aspirin or who have increased risk of haemorrhage.
(PPP, 401) May enhance absorption of sulphaguanidine. (ESCOPM, 1);
Augments the anticoagulant effect, thus altering clotting or bleeding
times |
|
Ginko Ginko biloba |
Warfarin sodium, heparin, aspirin and other anticoagulants |
Augments the anticoagulant effect, thus altering clotting or bleeding
times |
|
Ginseng and other herbs that contain cardiac
glycosides |
Insulin and related drugs for diabetes mellitus; Digoxin; Warfarin
soldium, heparin, aspirin and other anticoagulants |
Affects glucose levels; compromises dosage potency; alters bleeding or
clotting times |
|
Golden Seal Hydrastis canadensis |
Berberine, an alkaloid constituent of this herb, may reinforce the
effects of other drugs which displace the protein binding of bilirubin.
(PPP, 295) |
Contraindicated in hypertensive conditions. (PPP, 294) Fresh plant may
cause irritation to the mucosa. (BSH, 62) Canadian regulations do not
allow golden seal as a non-medicinal ingredient for oral use products. (BSH,
62) |
Hawthorn
Crataegus monogyna
|
digitalis glycosides,
beta-blockers and other hypotensive drugs |
May potentate the actions of
digitalis, though this action has not been confirmed. (HM, 186-188)
Hawthorn may act in synergy with digitalis glycosides, beta-blockers and
other hypotensive drugs. Modification of drug dosage may be required.
(PPP, 446) Drug interactions are also theoretically possible with
cardioactive medications. (TCPHP, 257) |
|
Kava Kava Piper methysticum |
Potentiation of effectiveness is possible for substances on the central
nervous system, such as alcohol, barbituates and psychopharmacological
agents. (TGHM, 156; PPP, 462) Caution indicated with medications for
insomnia or anxiety such as benzodiazepine. (PPP, 463; TCPHP, 33) There
is a risk of sudden abnormal movements (a dystonic reaction) when
combined with antipsychotic drugs. (TCPHP, 37) May reduce the efficacy
of Levodopa, a medication for Parkinson’s disease; may interact with
antiplatelet drugs or anticoagulants (e.g., warfarin, heparin) however
there are no case reports of such interactions. (TCPHP, 36) |
Extended use can cause discoloration of the skin, nails, and hair. (TGHM,
156; PPP, 462) In rare cases, contact type dermatitis can occur. (PPP,
462) Also accommodative disturbances, such as enlargement of the pupils
and disturbances of the oculomotor equilibrium, have been reported. (TGHM,
156; TCPHP, 35) Contraindicated in endogenous depression. (HM, 223)
Chronic usage may result in skin rash, shortness of breath, liver damage
and neurological manifestations may occur. (PPP, 463) dermatologic and
neurologic concern based upon case reports. (TCPHP, 301) Do not exceed
recommended dose. (BSH, 86) |
|
Korean Ginseng Panax
ginseng |
May interact with monoamine
oxidase inhibitor phenelzine and also with warfarin. (PPP, 429; WHO,
176). Do not use with stimulants, including excessive use of caffeine.
(HM, 174, PPP, 429) |
Contraindicated for
hypertension. (BSH, 81; HM, 174) Contraindicated with signs of heat,
acute infections, acute asthma, hypertension, excessive menstruation or
nose bleeds. (PPP, 429; CAACH, 41) Consuming caffeine with ginseng
increases the risk of overstimulation and gastro-intestinal upset. (BSH,
81; BHC, 116) Higher doses can over-stimulate and aggravate insomnia,
irritability, depression, headache, palpitation, hypertension, and can
cause tremor, euphoria, skin eruptions, menstrual abnormalities,
diminished sexual function and weight loss. (BSH, 81; CAACH, 40). May
reduce blood glucose levels, diabetic patients should consult with
physician. (WHO, 176) |
|
Licorice Glycyrrhiza glabra |
Should not be taken concurrently with corticosteroid treatment. (WHO,
190; AEHD, 77) Concurrent use of furosemide may potentiate development
of acute renal failure. (AEHD, 77) Potassium loss due to other drugs,
e.g. thiazide diuretics, can be increased. With potassium loss,
sensitivity to digitalis glycosides increases. (HM, 237; TGHM, 161; WHO,
190) Should not be administered in conjunction with spironolactone or
amiloride. (WHO, 190) Insulin may be synergistic with glycyrrhizin in
causing electrolyte disturbances and suppression of renin and
aldosterone. (AEHD, 77) |
It is recommended that patients with cardiovascular or renal disease use
licorice only under care of physician. (TCPHP, 232; PPP, 474) Patients
prone to potassium deficiency are also advised not to use licorice. (TCPHP,
232; TGHM, 161) Treatment not to exceed six weeks. (TCPHP, 232; BSH, 58;
TGHM, 162) Contraindications: cholestatic liver disorders, liver
cirrhosis, hypertonia, hypokalemia, and severe kidney insufficiency.
(HM, 236; BSH, 58; BHC,146; TGHM, 161; WHO, 190; AEHD, 72) Also
contraindicated if there is edema or congestive heart failure. (PPP,
474) Ingestion of large amount can lead to severe hypertension, cardiac
arrhythmias, cardiomyopathy, and cardiac arrest. (AEHD, 73; BSH, 58; BHC,
146; AEHD, 72) |
|
Marshmallow Althaea
officinalis |
Absorption of other drugs
taken simultaneously may be delayed. (BSH, 9; HM, 245, 247; ESCOPM, 1;
TGHM, 166, 167) |
As a mucilage or respiratory
demulcent, contraindicated or at least inappropriate in congestive
bronchial, catarrhal and congestive conditions of the mucosa. (PPP, 169,
211) |
Oregon Grape
Berberis aquifolium
|
Berberine, an alkaloid
constituent of this herb, may potentiate other drugs which displace the
protein binding of bilirubin. (PPP, 295) |
This herb is classified as a
choleretic and cholagogue. It is either contraindicated or at least
inappropriate in the following: (1) obstructed bile ducts, (2)
unconjugated hyperbilirubinaemia, (3) acute or severe hepatocellular
disease, (4) septic cholecystitis (where there is risk of peritonitis),
(5) intestinal spasm or ileus, and (6) liver cancer. (PPP, 187) As an
alterative, this herb may be provocative to skin disease, and care needs
to be taken to reduce the prospects of exacerbations. (PPP, 254) |
|
Pau D'Arco
Tabebuia avellanedae |
Patients on anticoagulant
therapy should not be prescribed Pau D’Arco due to the warfarin-like
action of naphthoquinones at high doses. (PPP, 504) |
Contraindicated with
anticoagulants. (PPP, 504) Adverse effects are not expected when
consumed with the recommended dosage. (PPP, 500) |
|
St. John's Wort Hypericum perforatum |
None known. (ESCOPM, 2; TGHM, 215; HM, 363) May potentiate
pharmaceutical MAO-inhibitors. (BSH, 62, 173) Recommend physician
consultation when taken with MAO inhibitors, SSRIs, and tricyclics.
(PPP, 549); Drugs for iron therapy |
Contraindicated in the treatment of serious depression with psychotic
symptoms, suicidal risk or signs and symptoms that are so severe that
they do not allow the patient’s family or work involvements to continue.
(PPP, 549) May cause mild stomach discomfort, skin rash, tiredness,
fatigue, sleep disturbances, photosensitization is possible, especially
in fair skinned individuals. (BSH, 62; TGHM, 215; HM, 363; PPP, 548;
ESCOPM, 1996, 1) Caution advised in very severe debility, especially if
associated with immune or digestive collapse, renal or hepatic failure,
rampant cancer or strong regimes of chemotherapy. (PPP, 155)
dermatologic and neurologic concern based upon case reports. (TCPHP,
301); Inhibits iron absorption |
|
Sarsaparilla Smilax
ornata |
Commission E advises of
potential drug interactions with hypnotics, digitalis glycosides, and
bismuth. However, no other reference substantiates these concerns. (BSH,
108) |
Risks: taking the herb may
lead to gastric irritation and temporary kidney impairment [diuresis].
The absorption of simultaneously administered substances may be
increased. The elimination of other substances (e.g., hypnotics) is
accelerated. This can cause an uncontrolled condition of increased or
decreased action of herbs taken simultaneously. (TGHM, 372) |
|
Tribulus Tribulus terrestris |
This herb may increase FSH in women, which in turn increases levels of
oestrogen. (PPP, 46) |
Due to the presence of saponins, this herb may be a gastrointestinal
irritant. (PPP, 46) |
Turmeric
Curcuma longa
|
None known. (HM, 382; TGHM,
222) High doses should not be given to patients taking antiplatelet or
anticoagulant drugs. (PPP, 578) |
Contraindicated in
obstruction of bile passages; in case of gallstones, use only after
consulting with a physician. (TGHM, 222; HM, 382; WHO, 121; PPP, 578)
The herb should not be administered to patients who suffer from stomach
ulcers or hyperacidity. (BSH, 39; HM, 382) Occasional cases of allergic
dermatitis reported. (WHO, 121; PPP, 578) Patients applying topical
doses should be cautioned against excessive exposure to sunlight. (PPP,
578) |
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Valerian Valeriana officinalis |
None known. (TGHM, 226; ESCOPM, 2; HM, 397) May increase the effects of
CNS depressants or alcohol when taken together. (PPP, 587; AEHD, 172;
WHO, 273) The herb may be expected to have at least an additive effect
with barbiturates, alcohol, benzodiazepines, and other CNS depressants.
(TCPHP, 64); diphenlydramine |
Can aggravate a sensation of tiredness or drowsiness, particularly in
higher doses. (PPP, 587; WHO, 273) Overdose can result in blurred
vision, erratic heart beat, headache, nausea, restlessness, visual
illusions, even spasmodic movements. (PPP, 588; BSH, 120) Very large
doses may cause bradycardia and arrhythmias, and decrease intestinal
motility. (WHO, 274) Canada allows products containing valerian for use
as sleeping aids and sedatives. (TCPHP, 64) Hepatic and neurologic
concern based upon case reports, although in the case of alleged
hepatotoxicity coingestants were involved. (TCPHP, 301) |
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Yohimbe Pausinystalia yohimbe |
Monoaminoxidase inhibitors |
Causes hypertension, insomnia, headache, and tremulousness |
http://rainforesttreasure.com/drug_interact.asp |
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