Many herbs can interfere with prescription drugs, or can be dangerous
if taken in large quantities. Always check with your doctor before
taking any herbal remedy or dietary supplement.
Bromelain (Pineapple enzyme) - May increase the effect of
blood-thinning drugs (e.g. Warfarin, Heparin).
Cat's Claw - May increase the risk of bleeding if taken
with blood-thinning drugs (e.g. Warfarin, Heparin).
Cayenne Pepper - Reports of possible interaction with MAO
inhibitors and antihypertensive therapy (used to lower blood pressure).
In large quantities, may cause damage to liver and kidneys.
Chamomile - Contains coumarin, but chamomile's effects
on the body's anticoagulation system have not been studied. If used
with anticoagulants such as warfarin, close monitoring by a doctor
Devil's Claw - May interfere with antacids, cardiac or diabetic
medications. Use with caution is taking NSAIDs, which can irritate
the stomach, as it can stimulate stomach acids.
DHEA - May cause liver damage if taking azathioprine or
methotrexate. Can increase insulin resistance or sensitivity in
Dong Quai - May interact with blood-thinning medications
(e.g. Warfarin, Heparin). May increase sun sensitivity.
Echinacea - May be toxic to the liver if used for more
than eight weeks. Should not be used with drugs that can cause liver
problems, such as anabolic steroids, amiodarone, methotrexate and
ketoconazole. Should not be given with immunosuppressants such as
corticosteroids and cyclosporine because it can stimulate the immune
Evening primrose oil and borage (GLA) - Should not be used
with anticonvulsants because they may lower the seizure threshold.
Not recommended for patients diagnosed with schizophrenia. May increase
the effects of anticoagulants and NSAIDs.
Feverfew - Effect on migraine headaches may be compromised
by non-steroidal anti-inflammatory drugs, such as aspirin and ibuprofen.
May increase blood-thinning effect of Warfarin or other anticoagulants,
including NSAIDs. Not to be used if pregnant, as it may cause miscarriage.
Fish Oil (Omega-3 fatty acids) - May increase the blood-thinning
effects of anticoagulants and NSAIDs.
Garlic - Should not be used with warfarin or other anticoagulents,
because it affects clotting. May also interact with hypoglycemic
medications, and anti-inflammatory drugs.
Ginger - Should not be used with warfarin because it affects
clotting. Do not use if you have gallstones. Large quantities may
interfere with cardiac, antidiabetic or anticoagulant (Warfarin,
Gingko - Can inhibit clotting so should not be used with
aspirin or other non-steroidal anti-inflammatory drugs or with anticoagulants
such as warfarin or heparin. Also should not be used in conjunction
with anticonvulsant drugs used by epileptics, such as carbamazepine,
phenytoin and phenobarbital, or with tricyclic antidepressants.
Ginseng - Should not be used with warfarin, heparin, aspirin
and other non-steroidal anti-inflammatory drugs because it can inhibit
clotting. Also may cause headache, tremulousness and manic episodes
in patients treated with phenelzine sulfate. Should not be used
with estrogens or corticosteroids because it may add to those drugs'
side effects. May also interfere with the heart drug digoxin or
with digoxin monitoring. Should not be used by diabetics because
it can affect blood glucose levels.
Goldenseal - Should be avoided by people with high blood
pressure. May interfere with anticoagulant therapy (Heparin).
Karela - Should not be used by patients with diabetes because
it can affect blood glucose levels.
Kava - Should not be used with the tranquilliser alprazolam
because it may result in coma. Do not take with sleeping medications
Kelp - May interfere with thyroid replacement therapies.
Liquorice - Can offset the effect of the diuretic drug
spironolactone. May also interfere with heart drug digoxin or with
digoxin monitoring. Potassium loss due to other drugs, e.g., thiazide
diuretics, can be increased.
Melatonin - Appears to boost the immune system, so should
be avoided by people with autoimmune diseases including lupus.
St. John's Wort - Can produce skin reactions to light so
fair-skinned users may wish to take care and anyone taking other
drugs that cause light sensitivity, such as piroxicam or tetracycline,
may want to avoid this herb. The active ingredient in St. John's
Wort is uncertain, so it should not be used with two common types
of psychiatric drugs called monoamine oxidase inhibitors and selective
serotonin reuptake inhibitors. Tannic acid in the herb may inhibit
absorption of iron. Can block the effects of drugs, including oral
contraceptives, tricyclic antidepressants, cyclosporin, several
heart drugs and warfarin.
Stinging Nettle - May increase the effects of tranquilisers
and sedative drugs. May decrease the effect of certain cardiac and
Valerian - Should not be used with barbiturates, such as
thiopental and pentobarbital -can cause excessive sedation. Do not
use if taking tranquilisers or sleep medications, as it increases
White willow bark - Aspirin is made from the drug salaicin,
which is contained in White Willow Bark .Do not take with aspirin
or other NSAIDs, as it increases their effects. May increase the
effects of anticoagulant drugs (e.g. Warfarin, Heparin).