** (Please see the warning from the UK Government's
Committee on Safety of Medicines, before taking St John's Wort.)
St John's Wort (Hypericum Perforatum) has been labelled the new
Prozac. In Germany it is prescribed to patients at least twice as
often as the Prozac type drugs, the selective serotonin re-uptake
inhibitor (SSRI) family. St John's Wort works in the same way as
SSRIs, by inhibiting re-absorption of the brain chemical serotonin,
keeping the natural serotonin around the synapses (junctions between
nerve cells by which messages are passed throughout the brain) for
longer, thereby producing good feelings. Serotonin is essential
for normal, healthy mental wellbeing, & when not enough of it
is present, or if it is dispersing too quickly from the areas where
it is most needed, a depression often results.
For those currently taking prescription anti-depressants-
If you are taking prescription antidepressants & want to switch
to St John's Wort, you must observe certain safeguards-
Do not stop taking prescription antidepressants without proper
medical care. The withdrawal effects of stopping them too abruptly
can be severe.
Do not take St John's Wort for severe depression or bipolar (manic
depressive) illness. Not enough research has been done on St John's
Wort in relation to these types of depression.
Do not take St John's Wort while taking mono-amino-oxidase (MAO)
inhibitors such as Nardil, Parstelin, or Parnate. It appears that
St John's Wort works at least in part as a serotonin re-uptake inhibitor
(SRI), & combining an SRI with an MAO inhibitor can produce
a dangerous rise in blood pressure. After stopping MAO inhibitors,
you should wait four weeks before taking SRIs (prescription or St
The best way to change from SRIs (Prozac, Seroxat, Cipramil, etc)
to St John's Wort is not known. If St John's Wort acts as a serotonin
uptake inhibitor in the same way as prescription SRIs, then it would
appear that gradual introduction of St John's Wort while tapering
off the prescription antidepressant would be in order. St John's
Wort appears to take longer than prescription antidepressants to
reach maximum effect. At the same time, care must be taken not to
take too many SRIs, to avoid the medical condition known as Serotonin
Syndrome, where the brain has too much serotonin.
It is reported that the benefits of St John's Wort can be felt
after taking a 300mg tablet three times daily for a month. It is
not a good idea to take any self-prescribed supplements indefinitely,
so take a break from the St John's Wort after about 6 months, by
which time your serotonin levels may have corrected themselves.
If you start to relapse, then start taking it again.
Unlike prescription drugs or generic drugs, herbal preparations
are sold in a variety of formulations & methods of extraction.
So when buying St John's Wort, you don't know what you're getting.
Try to buy a reputable make of St John's Wort, such as Kwai, or
Side effects of high doses of St John's Wort may include heightened
sensitivity to sunlight, & more rarely stomach irritation, allergic
reaction, tiredness & restlessness.
St John's Wort warning, from the UK
Government's Committee on Safety of Medicines
MESSAGE FROM PROFESSOR A BRECKENRIDGE, CHAIRMAN, COMMITTEE ON SAFETY
OF MEDICINES. 29 FEBRUARY 2000
IMPORTANT INTERACTIONS BETWEEN ST JOHN'S WORT (HYPERICUM PERFORATUM)
PREPARATIONS AND PRESCRIBED MEDICINES
This is to inform you of new evidence of important interactions
between St John's Wort (Hypericum perforatum) preparations and certain
prescribed medicines leading to loss of therapeutic effect of the
prescribed medicines. St John’s Wort (SJW) preparations are unlicensed
herbal remedies. Their levels of active ingredients can vary from
one preparation to another. They are available from pharmacies,
health food shops and herbal practitioners. Because St John’s Wort
preparations are so widely available, your patients may be taking
them without your knowledge. This letter and the enclosed Fact Sheets
summarise the Committee on Safety of Medicines’ (CSM) advice and
provide guidance on management of patients.
New evidence suggests that preparations of St John's Wort are inducers
of various drug metabolising enzymes. This may result in a reduction
in blood levels and therapeutic effect of some medicines metabolised
by these enzymes. Because levels of active ingredients can vary
from one preparation of St John's Wort to another, and patients
may switch between preparations, the degree of induction is likely
to vary. It is important to note that when patients stop taking
a preparation containing St John’s Wort, blood levels of interacting
medicines may rise resulting in toxicity. CSM has advised that St
John’s Wort should not be used with the following medicines:
· oral contraceptives
Although there is no direct evidence, clinically important interactions
are also likely with: · other HIV protease inhibitors (saquinavir,
ritonavir, nelfinavir) · HIV non-nucleoside reverse transcriptase
inhibitors (efavirenz, nevirapine) · anticonvulsants (phenytoin,
Furthermore, St John’s Wort preparations affect neurotransmitters
in the brain and may interact with psychotropic medicines including
Selective Serotonin Reuptake Inhibitors (SSRIs). St John’s Wort
preparations may also have pharmacodynamic interactions with triptans
used to treat migraine. These interactions may result in serious
Patients already taking these prescribed medicines should not take
St John’s Wort. Doctors and pharmacists are advised to ask patients
about use of non-prescription medicines including herbal remedies.
Specific advice on dealing with the interactions listed above is
given in Table 1 of the attached Fact Sheet. Please note that the
action of many other drugs depends on their rate of metabolism and
thus other drugs may also interact with St John’s Wort preparations.
St John’s Wort preparations are unlikely to interact with topical
medicines with limited systemic absorption and non-psychotropic
medicines which are excreted renally.
Suspected interactions with St John’s Wort preparations should
be reported to the Medicines Control Agency/Committee on Safety
of Medicines through the Yellow Card Scheme. Professor A Breckenridge
Chairman, Committee on Safety of Medicines
FACT SHEET FOR HEALTH CARE PROFESSIONALS
Why do SJW preparations interact with other medicines? New evidence
suggests that SJW preparations may interact with medicines, either
by affecting drug metabolism or levels of neurotransmitters. Drug
metabolism may be affected by SJW preparations inducing certain
cytochrome P450 isoenzymes in the liver (CYP 3A4, 1A2 and 2C9),
as well as, P-glycoprotein. Pharmacodynamic (additive or potentiating)
interactions may occur through the effects of SJW preparations on
neurotransmitters in the brain (SJW may increase serotonin levels
through weak monoamine oxidase inhibiting (MAOI) activity and serotonin
What is the clinical significance of these interactions? Induction
of drug metabolism increases the breakdown of drugs so reducing
their blood levels and therapeutic effects. Because the levels of
active ingrediants can vary between preparations of SJW and patients
may switch between preparations, the degree of induction is likely
to change over time. When patients stop taking SJW preparations,
blood levels of interacting medicines may rise, leading to toxicity.
Pharmacodynamic (additive or potentiating) interactions may occur
with psychoactive medicines including Selective Serotonin Reuptake
Inhibitors (SSRIs). St John’s Wort preparations may also have pharmacodynamic
interactions with triptans used to treat migraine. These interactions
may result in serious adverse reactions.
Which medicines interact with SJW? Table 1 lists medicines where
in-vitro studies, pharmacokinetic studies or spontaneously reported
suspected adverse reactions demonstrate clinically important interactions.
In addition, other drugs are included where evidence is lacking
but clinically important interactions are likely. Please note that
the action of many other drugs depends on their rate of metabolism
and thus other drugs may also interact with SJW preparations. In
general, the following medicines are not likely to interact with
SJW preparations: · topical medicines with limited systemic absorption
(inhalers, creams, ointments, eye and ear drops, enemas etc). ·
Non-psychotropic medicines which are renally excreted.
-I am currently taking a St John’s Wort preparation, and I am not
taking any medicine(s). Advice: If you buy a medicine from a pharmacy
or are prescribed a medicine by your doctor you must tell your pharmacist
or doctor about the St John’s Wort preparation.
- I am already taking medicine(s) but I would like to start taking
a St John’s Wort preparation. Advice: You must not take a St John’s
Wort preparation until you have checked with your pharmacist or
doctor that it is safe for you to do so.
- Epilepsy or fits: I am on tablets for epilepsy/fits and I am
also taking a St John’s Wort preparation, Transplant: I am on tablets
following a transplant and I am also taking a St John’s Wort preparation.
Asthma or chronic bronchitis: I am on theophylline tablets for my
chest and I am also taking a St John’s Wort preparation
Heart condition: I am taking digoxin for a heart condition and I
am also taking a St John’s Wort preparation
Blood clots: I am taking warfarin to thin my blood and I am also
taking a St John’s Wort preparation,
Advice for patients with any of these conditions: You will need
to stop taking the St John’s Wort preparation as it may stop your
medicine from working properly. However, you should see your pharmacist
or doctor before stopping the St John’s Wort Preparation as the
dose of your medicine may need to be altered to prevent side effects.
-Contraceptive pill: I am on the pill and I am also taking a St
John’s Wort preparation, Advice: You should stop taking the St John’s
Wort preparation as it may stop your pill from working. Continue
to take your contraceptive pill as normal. There is no need to see
your pharmacist or doctor urgently, however, mention it when you
next consult your doctor or are dispensed a medicine.
-Migraine : I take treatment for migraine and I am also taking
a St John’s Wort preparation, Depression: I am on treatment for
depression and I am also taking a St John’s Wort preparation,. Advice:
You should stop taking the St John’s Wort preparation as it may
stop your medicine from working. There is no need to see your pharmacist
or doctor urgently, however, mention it when you next consult your
doctor or are dispensed a medicine
- I am currently taking both a St John’s Wort preparation and a
prescribed medicine not mentioned above. Advice: Tell your pharmacist
or doctor that you are taking a St John’s Wort preparation when
you are next dispensed a medicine or consult your doctor.
· It is important to always tell your pharmacist or doctor about
any herbal remedy or over the counter medicine you are taking.