Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
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,
breastfeeding, for pediatric patients, 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
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
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.
Data is coming, although slowly. Dr. Lucinda Miller of Texas
Tech University Health Sciences reviewed known herb-drug
interactions. Her review was published for doctors in the medical
journal Archives of Internal Medicine. The list that follows is derived from this article and includes summaries
of various herbs with particular focus on potential herb-drug
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.
Chamomile drug interactions
Uses: Chamomile is often used in the form of a tea as a sedative.
Drug interactions: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)
Echinacea drug interactions
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.
Uses:St. John's Wort is popularly used as an herbal treatment for
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).
Drug interactions: 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 (Feldene). St. John's wort can also cause
sweating, and agitation when used in combination with
serotonin reuptake inhibitor medications (SSRIs) such as
and paroxetine (Paxil).
Garlic Drug interactions
Uses:Garlic has been used to
blood pressure and
(Dr. Lucinda Miller notes that there is "...still insufficient evidence
to recommend its routine use in clinical practice.")
Drug interactions: 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).
Drug interactions: Feverfew can cause allergic reactions, especially in
persons who are allergic to chamomile, ragweed, or yarrow.
NSAIDs such as
naproxen (Aleve) or
Motrin can reduce the effect of feverfew. A
condition called "post-feverfew syndrome" features symptoms including
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).
Ginkgo Biloba drug interactions
Uses: This herb is very popular as a treatment for
progressive brain dysfunction) and to improve thinking.
Drug interactions: Mild stomach upset and
headache have been reported.
seems to have blood thinning properties. Therefore, it is not
recommended to be taken with
aspirin, nonsteroidal anti-inflammatory
drugs such as ibuprofen (Advil), naproxen (Aleve) or Motrin, or
medications to prevent blood clotting (anticoagulants) such as warfarin (Coumadin). Ginkgo should be avoided in patients with
medicines, such as
(Tegretol), and phenobarbital.
Ginseng drug interactions
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.")
Drug interactions: Ginseng can cause elevation in blood pressure,
nose bleeding. Ginseng can also cause falsely
abnormal blood tests for
(Lanoxin) levels in persons taking the drug for
heart disease. 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
anti-inflammatory drugs such as ibuprofen (Advil), naproxen (Aleve) or Motrin, or medications to prevent blood clotting
(anticoagulants) such as warfarin (Coumadin). Ginseng may also cause
tremors, nervousness, and
sleeplessness. It should be
avoided in persons with
manic disorder and psychosis.
Ginger drug interactions
Uses: Ginger has been used as a treatment for
nausea and bowel spasms.
Drug interactions: 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 drug interactions
Saw palmetto has been most commonly used for
enlargement of the
prostate gland. Saw palmetto has also been touted as a
diuretic and urinary antiseptic to prevent
bladder infections. However,
according to the National Institutes of Health (NIH), there is insufficient
scientific evidence to support the use of saw palmetto for treatment of enlarged
prostate or any other conditions.
Drug interactions: Saw palmetto can cause
upset stomach. 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 (for example,
This listing represents only a small portion of herbal
treatments. Nevertheless, the popularity of herbal therapies is
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.
Medically reviewed by John A. Daller, MD; American Board of Surgery with subspecialty certification in surgical critical care
L. Miller. "Herbal Medicinals." Archives of Internal
UpToDate. Clinical use of saw palmetto.
Medically Reviewed by a Doctor on 12/1/2016
Get the latest health and medical information delivered direct to your inbox!