Common Herbs

Herbs: Toxicities and Drug Interactions

Any conventional Medication can have side effects. These side effects are described and reported after drug trials and research studies have been conducted. Side effects are further reported and evaluated after the marketing of the medication. Information about drug components, interactions, usage in pregnancy, nursing and childhood, and dosing limits are outlined and made available in standard references for doctors treating patients. Furthermore, the formulations of the drugs must satisfy strict quality control standards to ensure conformity. These medications regularly contain virtually uniform quantities and ratios of substances.

In contrast to conventional medications, unconventional treatments (such as herbs) have little or no actual scientific basis so doctors can guide their patients regarding proper usage or potential toxicity. There are no standardized references and most of the herbal formulations have not been analyzed, are not uniform, and have not been quality controlled. One batch can be very different from the next.
Moreover, even if a given herb has a known toxicity, the manufacturer may or may not warn consumers. Manufacturers are not required to alert consumers to known dangers.

The point is that these "supplements" are not sanctioned, regulated, or supervised by any agency.
The data are coming, although slowly. Dr. Lucinda Miller of Texas Tech University Health Sciences recently reviewed known herb-drug interactions. Her review was published for doctors in the medical journal Archives of Internal Medicine 1998;158:2200- 2209. The list that follows is derived from this article and includes summaries of various herbs with particular focus on potential herb-drug interactions.
Keep in mind that the information in the "Uses" section is for the most part unsupported by verification of scientific studies. It should be noted that simply because herbs are "natural" treatments, they are not necessarily free from side effects.

[ Heroin ] -
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[Valarian ]
Chamomile
Echinacea
St. John's Wort
Garlic
Feverfew
Ginko Biloba
Ginseng
Ginger
Saw Palmetto
Black Cohosh

Chamomile

Uses: Chamomile is often used in the form of a tea as a sedative.

Reactions: Allergic reactions can occur, particularly in persons allergic to ragweed. Reported reactions include abdominal cramps, tongue thickness, tightness in the throat, swelling of the lips, throat and eyes, itching all over the body, hives, and blockage of the breathing passages. Close monitoring is recommended for patients who are taking medications to prevent blood clotting (anticoagulants) such as warfarin.

Echinacea

Uses: Largely because white blood cells in the laboratory can be stimulated to eat particles, Echinacea has been touted to be able to boost the body's ability to fight off infection.
Reactions: The most common side effect is an unpleasant taste. Echinacea can cause liver toxicity. It should be avoided in combination with other medications that can affect the liver (such as ketaconazole, leflunomide (Arava), methotrexate (Rheumatrex), isoniazide (Nizoral).

St. John's Wort

Uses: St. John's Wort is popularly used as an herbal treatment for depression, anxiety, and sleep disorders. It is technically known as Hypericum perforatum. Chemically, it is composed of at least 10 different substances that may produce its effects. The ratios of these different substances varies from plant to plant (and manufacturer). Studies of its effectiveness by the National Institutes of Health are in progress.
Reactions: The most common side effect has been sun sensitivity which causes burning of the skin. It is recommended that fair- skinned persons be particularly careful while in the sun. St. John's wort may also leave nerve changes in sunburned areas. This herb should be avoided in combination with other medications that can affect sun sensitivity (such as tetracycline/Achromycin, sulfa- containing medications, piroxicam (Feldend). St. John's wort can also cause headaches, dizziness, sweating, and agitation when used in combination with serotonin reuptake inhibitor medications such as fluoxetine (Prozac) and paroxetine (Paxil).

Garlic

Uses: Garlic has been used to lower blood pressure and cholesterol (Dr. Lucinda Miller notes that there is "...still insufficient evidence to recommend its routine use in clinical practice.")
Reactions: Allergic reactions, skin inflammation, and stomach upset have been reported. Bad breath is a notorious accompaniment. Studies in rats have shown decreases in male rats' ability to make sperm cells. Garlic may decrease normal blood clotting and should be used with caution in patients taking medications to prevent blood clotting (anticoagulants) such as warfarin /Coumadin.

Feverfew

Uses: Most commonly used for migraine headaches.
Reactions: Feverfew can cause allergic reactions, especially in persons who are allergic to chamomile, ragweed, or yarrow. Nonsteroidal anti-inflammatory drugs (NSAIDs such as ibuprofen (Advil), naproxen (Aleve) or Motrin) can reduce the effect of feverfew. A condition called "postfeverfew syndrome" features symptoms including headaches, nervousness, stiffness, joint pain, tiredness, and nervousness. Feverfew can impair the action of the normal blood clotting element (platelets). It should be avoided in patients taking medications to prevent blood clotting (anticoagulants) such as warfarin (Coumadin).

Ginko Biloba

Uses: This herb is very popular as a treatment for dementia (a progressive brain dysfunction) and to improve thinking.
Reactions: Mild stomach upset and headache have been reported. Ginko seems to have blood thinning properties. Therefore, it is not recommended to be taken with aspirin, nonsteroidal anti-inflammatory drugs (Advil), naproxen (Aleve) or Motrin), or medications to prevent blood clotting (anticoagulants) such as warfarin (Coumadin). Ginko should be avoided in patients with epilepsy taking seizure medicines, such as phenytoin (Dilantin), carbamazepine (Tegretol), and phenobarbital.

Ginseng

Uses: Ginseng has been used to stimulate the adrenal gland, and thereby increase energy. It also may have some beneficial effect on reducing blood sugar .in patients with diabetes mellitus. (Dr. Miller emphasized that there is substantial variation in the chemical components of substances branded as "Ginseng.")
Reactions: Ginseng can cause elevation in blood pressure, headache, vomiting, insomnia, and nose bleeding. Ginseng can also cause falsely abnormal blood tests for digoxin level. It is unclear whether ginseng may affect female hormones. Its use in pregnancy is not recommended. Ginseng may affect the action of the normal blood clotting element (platelets). It should be avoided in patients taking aspirin, nonsteroidal antiinflammatory drugs (such as ibuprofen (Advil), naproxen (Aleve) or Motrin), or medications to prevent blood clotting (anticoagulants) such as warfarin (Coumadin). Ginseng may also cause headaches, tremors, nervousness, and sleeplessness. It should be avoided in persons with manic disorder and psychosis.

Ginger

Uses: Ginger has been used as a treatment for nausea and bowel spasms.
Reactions: Ginger may lead to blood thinning. It is not recommended to be taken with medications that prevent blood clotting (anticoagulants) such as warfarin (Coumadin).

Saw Palmetto

Uses: Saw palmetto has been most commonly used for enlargement of the prostate gland. (Dr. Miller emphasized that studies verifying this assertion are necessary.) Saw palmetto has also been touted as a diuretic and urinary antiseptic to prevent bladder infections.
Reactions: This herb may affect the action of the sex hormone testosterone, thereby reducing sexual drive or performance. Dr. Miller states that "While no drug-herb interactions have been documented to date, it would be prudent to avoid concomitant use with other hormonal therapies (e.g., estrogen replacement therapy and oral contraceptives...")
This listing represents only a small portion of herbal treatments. Nevertheless, the popularity of herbal therapies is unquestionable. Doctors routinely confront the unknown with their patients who are using herbs. Doctors simply do not have any way of helping you to decide whether these herbs are helpful or harmful for you, or whether they are interacting with your current medications. There are no data.

Black Cohosh

Claims, Benefits: A natural way to treat menopausal symptoms.
Bottom Line: Little is known about its benefits and its risks. If you try it, tell your physician, since it might interact with other medications you are taking.

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