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Herb-Medication Interactions: What You Don't Know Can Hurt You.

(Part one of a two-part series on drug interactions.)

Americans are taking herbal preparations more then ever, yet rarely inform their doctors, either because they view herbs as innocuous or because they fear the doctor's disapproval. But besides occasional side effects from the herbs themselves, there lies a greater danger--interactions with medications. Researchers are just beginning to explore what they see as the tip of this iceberg.

In the past decade, Americans' use of herbal preparations has increased nearly fourfold. And many of the people taking herbs are older people who take prescription medications as well. While this practice may seem benign-especially if an herb is harmless on its own--recent reports have highlighted serious consequences when some herbs are taken concurrently with drugs. For instance, there have been several cases of organ transplant rejection apparently caused by concomitant use of St. John's wort and cyclospofine, an anti-rejection medication commonly prescribed for transplant patients.

Other interactions are not so straightforward. Since herbal preparations sold in the U.S. are not required to adhere to any standards of potency, purity or efficacy, consumers are often in the dark about what may or may not be in the bottle they buy. One study found that 24% of Chinese herbal preparations evaluated contained unlisted drugs (diuretics or medication for inflammation and pain). Other reports have found the presence of contaminants like lead and arsenic.

Herbal remedies from reputable manufacturers are typically much more reliable, yet there is still the threat of interactions with legitimate drugs and even with over-the-counter medications. The solution is not to forgo herbal preparations, but to communicate with your doctor and your pharmacist about any supplements you are taking. If necessary, you can temporarily stop taking an herb, switch to a different remedy or have your doctor adjust your medicine's dose. You should also ask your doctor about what herbs and supplements to stop taking before surgery.

Below is a sampling of known interactions between herbs and many common medications.

Next month: EN's guide to food-medication interactions.
EN's Guide to Herb-Medication Interactions

Interactions are listed by drug category, followed by examples of specific
medications (with generic and brand names). For example, garlic interacts
with anticoagulants, such as warfarin sodium (Coumadin). But other
anticoagulants may interact as well. As always, alert your physician and
pharmacist to any over-the-counter medications, herbal remedies and
supplements you are taking.

Medications                                  What They Do
Generic name (sample brand names)

Cardiovascular Medications

Anti-Arrhythmia Medications:                 Improve the strength and
  digoxin (Lonoxicaps, Lanoxin)              efficiency of the heart by
  digitoxin (Crystodigin)                    regulating heart rate.
  propranolol HCI (Inderal)

Calcium Channel Blockers:                    Help to regulate heart rate,
  diltiazem (Cardizem, Dilacor XR, Diltia    relax blood vessels. Lower
    XT, Taztia XT)                           blood pressure. Ease chest
  nifedipine (Adalat, Procardia)             pain and congestive heart
  verapamil (Calan, Isoptin, Verelan)        failure.

Blood Thinners:                              Inhibit blood clotting.
  warfarin sodium (Coumadin)

Blood Pressure Medications:                  Decrease blood pressure.
  clonidine (Catapres)
  terazosin (Hytrin)

Diuretics:                                   Cause water loss, which
Thiazide Diuretics:                          reduces workload on the
  bendroflumethiazide (Naturetin)            heart.
  chlorothiazide (Diuril)
  hydrochlorothiazide (Esidrix,
    Hydrodiuril, Microzide, Oretic )
Loop Diuretics:
  bumetanide (Bumex)
  furosemide (Lasix)
  torsemide (Demadex)
spironolactone (Aldactone)                   Decreases blood pressure
amiloride (Midamor)                          but holds onto potassium.


methylprednisolone (Medrol)                  Treat inflammation, asthma
prednisone (Cordol, Deltasone, Orasone)      and arthritis.

Diabetes Medications

chlorpropamide (Diabenese)                   Treat type 2 diabetes by
glipizide (Glucotol, Glucotrol XL)           helping the pancreas
glyburide (DiaBeta, Glynase, Micronase)      release insulin into the
                                             blood stream.

Psychotherapeutic Medications

Antidepressants:                             Treat mental depression.
  amitriptyline (Elavil, Endep)
  imipramine (Tofranil)
  nortriptyline (Aventyl, Pamelor)

Selective Serotonin Re-uptake Inhibitors     Treat mental depression,
    (SSRI's):                                obsessive compulsive
  fluoxetine (Prozac, Sarafem)               disorder, panic disorder and
  paroxetine (Paxil)                         social anxiety disorder.
  sertraline (Zoloft)

Barbiturates:                                Treat anxiety or control
  phenobarbital (Barbita, Luminal,           epileptic seizures.

Benzodiazepines:                             Relieve anxiety.
  alprazolam (Alprazolam, Intensol, Xanax)
  diazepam (Valium, Diastat, Dizac)
  Iorazepam (Ativan)

Mood Stabilizers:                            Treat bipolar disorder.
  divalproex sodium (Depakote)
  lithium (Eskalith, Lithobid)

Monoamine Oxidase Inhibitors (MAOI's):       Relieve mental depression.
  isocarboxazid (Marplan)
  phenelzine (Nardil)
  selegiline (Carbex, Eldepryl)
  tranylcypromine (Pamate)

Other Medications

bisacodyl (Dulcolax)                         Stimulant laxative.

cyclosporine (Gengraf, Neoral, Sandimmune,   Prevents rejection of
  SangCya)                                   transplanted organs. Also
                                             used for severe rheumatoid
                                             arthritis or psoriasis.

idinavir (Crixivan)                          Treat HIV.
saquinavir (Fortovase, Invirase)

levodopa (Atamet, Larodopa)                  Treats Parkinson's Disease.

methotrexate (Rheumatrex)                    Used to treat several types
                                             of cancer.

theophylline (Quibron-T, Respbid, Slo-Bid    Treats and prevents the
Gyrocaps, Slo-Phyllin, Theo-24, Theobid      symptoms of asthma,
Duracpas, Theo-Dur, Theolair,, Theo-Time,    chronic bronchitis and
Uni-Dur, Uniphyl)                            emphysema.

Antibiotics:                                 Fight infection.
  ampicillin (Polycillin)
  ciprofloxacin (Cipro)

Anticonvulsants:                             Act on the central nervous
  ethosuximide (Zarontin)                    system to reduce number
  fosphenytoin (Cerebyx)                     and severity of seizures.
  phenytoin (Dilantin)

Estrogen Replacement:                        Female hormone
  conjugated estrogens (Premarin)            replacement.
  estradiol (Alora, Climara, Depogen,

Oral Contracentives:                         To prevent pregnancy.
  levonorgestrel & ethinyl estradiol
    (Alesse, Levlen, Levlite)
  norethindrone & ethinyl estradiol
    (Brevicon, Genora, Jenest,
    Ortho 7/7/7)

Over-the-Counter Medications

acetaminophen (Anacin-Free, Panadol,         Pain relief.

aspirin (Anacin, Bayer, Excedrin)            Pain relief.

Medications                                  Selected Herb Interactions
Generic name (sample brand names)            Common name (Latin name)

Cardiovascular Medications

Anti-Arrhythmia Medications:                 * Siberian ginseng
  digoxin (Lonoxicaps, Lanoxin)                (Eleutherococcus
  digitoxin (Crystodigin)                      senticosis) may falsely
                                               elevate digoxin levels.
                                             * The following contain
                                               digoxin-like substances
                                               and may contribute to
                                               digoxin toxicity:
                                               * milkweed
                                               * hawthorne leaf with
                                                 flower (Crategus spp.)
                                             * The following decrease
                                               digoxin concentrations in
                                               the blood:
                                               * St. John's wort
                                                 (Hypericum perforatum)
                                               * guar gum slows absorption

Calcium Channel Blockers:                    * The following cause
  diltiazem (Cardizem, Dilacor XR, Diltia      potassium losses and may
    XT, Taztia XT)                             trigger the toxicity of
  nifedipine (Adalat, Procardia)               certain cardiac
  propranolol HCI (Inderal)                    medications:
  verapamil (Calan, Isoptin, Verelan)          * aloe latex and drug aloe
                                                 (not juice) (Aloe vera)
                                               * buckthorn bark and berry
                                                 (Rhamnus frangula)
                                               * cascara sagrada bark
                                                 (Rhamus purshiana)
                                               * senna leaf (Cassia senna)

Blood Thinners:                              * The following have
  warfarin sodium (Coumadin)                   anticoagulant effects that
                                               may exacerbate the drug's
                                               effect, possibly
                                               triggering post-operative
                                               * dong quai (Angelica
                                               * fenugreek (Trigonelle
                                               * feverlew (Tanacetum
                                               * garlic (Allium sativum)
                                               * ginger (Zingiber
                                               * ginkgo (Ginkgo biloba)
                                                 may also cause brain
                                               * ginseng (Panax ginseng)
                                                 may also trigger blood

Blood Pressure Medications:                  * kava (Pipermethysticum)
  clonidine (Catapres)                         may cause lethargy and
  terazosin (Hytrin)                           disorientation.
                                             * The following increase
                                               blood pressure,
                                               counteracting the effects
                                               of the medication:
                                               * ma huang (Ephedra sinica)
                                               * yohimbe (Pausinystalia
                                               * fenugreek (Trigonelle
                                               * licorice (Glycyrrhiza
                                                 glabra) also increases
                                                 sodium and decreases

Diuretics:                                   * fenugreek (Trigonelle
Thiazide Diuretics:                            foenum-graecum) has
  bendroflumethiazide (Naturetin)              diuretic properties and
  chlorothiazide (Diuril)                      may exacerbate water loss.
  hydrochlorothiazide (Esidrix,              * ginkgo (Ginkgo biloba) may
    Hydrodiuril, Microzide, Oretic)            raise blood pressure with
Loop Diuretics:                                thiazide diuretics.
  bumetanide (Bumex)
  furosemide (Lasix)
  torsemide (Demadex)
spironolactone (Aldactone)                   * yohimbe (Pausinystalia
amiloride (Midamor)                            yohimbe) may counteract
                                               drug's effect.


methylprednisolone (Medrol)                  * betel nut (Areca catechu)
prednisone (Cordol, Deltasone, Orasone)        counteracts effects of
                                             * ginseng (Panax ginseng)
                                               may cause steroid toxicity.
                                             * licorice (Glycyrrhiza
                                               glabra) increases
                                               prednisone levels in blood
                                               and contributes to high
                                               blood pressure.

Diabetes Medications

chlorpropamide (Diabenese)                   * The following may decrease
glipizide (Glucotol, Glucotrol XL)             blood sugar, leading to
glyburide (DiaBeta, Glynase, Micronase)        hypoglycemia:
                                               * fenugreek (Trigonelle
                                               * ginseng (Panax ginseng)
                                               * karela or bitter melon
                                                 (Morodica charantia)
                                             * echinacea (Echinanacea
                                               purpurea) alters metabolic
                                               control in people with

Psychotherapeutic Medications

Antidepressants:                             * ginseng (Panax ginseng)
Tricyclics:                                    may cause mania.
  amitriptyline (Elavil, Endep)              * The following may enhance
  imipramine (Tofranil)                        the effects of tricyclics,
  nortriptyline (Aventyl, Pamelor)             causing restlessness:
                                               * ma huang (Ephedra)
                                               * St. John's wort
                                                 (Hypeifcum perforatum)
                                               * ginkgo (Ginkgo biloba)
                                               * yohimbe (Pausinystalia
                                                 yohimbe) may cause high
                                                 blood pressure with

Selective Serotonin Re-uptake Inhibitors     * The following may enhance
    (SSRI's):                                  the effects of SSRI's,
  fluoxetine (Prozac, Sarafem)                 causing restlessness:
  paroxetine (Paxil)                           * St. John's wort
  sertraline (Zoloft)                            (Hypericum perforatum)
                                               * mahuang (Ephedra)
Barbiturates:                                * The following enhance the
  phenobarbital (Barbita, Luminal,             effects of medication,
    Solfoton)                                  causing sleepiness and
                                               * valerian (Valeriana
                                               * St. John's wort
                                                (Hypericum perforatum)
                                               * kava (Piper methysticum)
Benzodiazepines:                             * The following enhance the
  alprazolam (Alprazolam, Intensol, Xanax)     effects of medication,
  diazepam (Valium, Diastat, Dizac)            causing sleepiness and
  Iorazepam (Ativan)                           lethargy:
                                               * kava (Piper methysticum)
                                               * valerian (Valeriana

Mood Stabilizers:                            * psyllium (Plantago avato)
  divalproex sodium (Depakote)                 decreases lithium
  lithium (Eskalith, Lithobid)                 concentration.
                                             * ginseng (Panax ginseng)
                                               may cause mania.

Monoamine Oxidase Inhibitors (MAOI's):       * St. John's wort (Hypericum
  isocarboxazid (Marplan)                      perforatum) slightly
  phenelzine (Nardil)                          inhibits effect of drug.
  selegiline (Carbex, Eldepryl)              * yohimbe (Pausinystalia
  tranylcypromine (Pamate)                     yohimbe) increases toxic
                                               effects of medication.
                                             * ma huang (Ephedra)
                                               enhances action of MAOI's,
                                               possibly resulting in
                                               life-threatening high
                                               blood pressure, high fever
                                               and coma.
                                             * ginseng (Panax ginseng)
                                               may cause headache, mania,

Other Medications

bisacodyl (Dulcolax)                         * The following
                                               herbs can enhance laxative
                                               * aloe (Aloe barbadensis)
                                               * cascara sagrada (Rhamnus
                                               * senna (Senna alexandrina)
                                               * yellow dock (Rumex

cyclosporine (Gengraf, Neoral, Sandimmune,   * St. John's wort (Hypericum
  SangCya)                                     perforatum) decreases
                                               amount of drug in blood,
                                               which may result in
                                               transplant rejection.
                                             * echinacea (Echinacea
                                               pupurea) alters immune
                                               function, possibly
                                               counteracting drug's

idinavir (Crixivan)                          * The following can decrease
saquinavir (Fortovase, Invirase)               effectiveness of the drug:
                                               * garlic
                                               * St. John's wort
                                                 (Hypericum perforatum)

levodopa (Atamet, Larodopa)                  * kava (Piper methysticum)
                                               may decrease drug's

methotrexate (Rheumatrex)                    * echinacea (Echinacea
                                               pupurea) may damage the

theophylline (Quibron-T, Respbid, Slo-Bid    * St. John's wort (Hypericum
Gyrocaps, Slo-Phyllin, Theo-24, Theobid        Perforatum) can inhibit
Duracpas, Theo-Dur, Theolair,, Theo-Time,      drug's effectiveness.
Uni-Dur, Uniphyl)

Antibiotics:                                 * The following decrease
  ampicillin (Polycillin)                      drug availability:
  ciprofloxacin (Cipro)                        * dandelion (Taraxacum
                                               * fennel (Foeniculum
                                               * khat (Catha edulis)

Anticonvulsants:                             * The following may
  ethosuximide (Zarontin)                      interfere with seizure
  fosphenytoin (Cerebyx)                       control:
  phenytoin (Dilantin)                         * evening primrose oil
                                                 (Primula veris)
                                               * ginkgo (Ginkgo biloba)
                                               * kava (Piper methysitcum)

Estrogen Replacement:                        * saw palmetto (Seronoa
  conjugated estrogens (Premarin)              serrulata) can exacerbate
  estradiol (Alora, Climara, Depogen,          breast tenderness

Oral Contracentives:                         * The following may increase
  levonorgestrel & ethinyl estradiol           blood pressure:
    (Alesse, Levlen, Levlite)                  * licorice (Glycyrrhiza
  norethindrone & ethinyl estradiol              glabra)
    (Brevicon, Genora, Jenest,                 * St. John's Wort
    Ortho 7/7/7)                                 (Hypericum perforatum)
                                                 may also cause
                                                 breakthrough menstrual

Over-the-Counter Medications

acetaminophen (Anacin-Free, Panadol,           * ginkgo (Ginkgo biloba)
  Tylenol)                                       may cause brain

aspirin (Anacin, Bayer, Excedrin)              * tamarind (Tamarindus
                                                 jadica) increases blood
                                                 levels of aspirin.
                                               * ginkgo (Ginkgo biloba)
                                                 may cause prolonged
                                                 bleeding and eye
                                               * garlic (Allium sativum)
                                                 can cause prolonged

Sources: An EN original compilation of information from journal articles and
experts in the field.

[C] Copyright, 2001 by Environmental Nutrition, Inc., 52 Riverside Drive,
New York, NY 10024;
COPYRIGHT 2001 Belvoir Media Group, LLC
No portion of this article can be reproduced without the express written permission from the copyright holder.
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Author:Golub, Catherine
Publication:Environmental Nutrition
Geographic Code:1USA
Date:Oct 1, 2001
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