St. John's Wort: Benefits, Dosage, Contraindications
Other name(s)
St. John's Herb
Scientific name(s)
Hypericum perforatum
Family or group:
Plants
Active ingredients:
Quercetin
Flavonoids
Hypericin
Hyperforin
Xanthophylls
Melatonin
Indications
Rating methodology
EFSA approval.
Depression ✪✪✪✪✪
The efficacy and safety of standardized hydro-alcoholic extracts of St. John's wort have been evaluated in more than 50 controlled double-blind studies involving 8,327 patients and 15 open studies, medication surveillance studies and numerous case reports that involved another 15,359 patients. The main indication in most studies was mild depressive disorders or mild to moderate. A significant improvement in the major symptoms (mood, loss of interest and activity) and other symptoms of depressive syndrome (sleep, concentration, somatic complaints) was demonstrated in many of these trials. The activity has even been studied in comparison with various antidepressants (Amitriptyline, Imipramine, Maprotiline, Fluoxetine, Sertraline, Citalopram). Nine meta-analyses and 18 systematic reviews of clinical trials with different selection criteria have confirmed the efficacy of various St. John's wort extracts in mild to moderate depression, but not in severe depression. Most clinical studies on the efficacy of St. John's wort used preparations containing St. John's wort extracts standardized to 0.3% hypericin or 3 to 6% hyperforin. To characterize mild to moderate depression, ESCOP proposed the ICD-10, or International Classification of Diseases, 10th Revision. It's a classification system used in the medical field to code diseases, their signs, and symptoms, as well as their social and environmental circumstances: Mild depressive episode: First mild manifestation or mild recurrence of at least two target signs and at least two associated symptoms. Moderate depressive episode: Two or three target signs and at least three or four associated symptoms (first manifestation or recurrent episode). The target signs are: a marked depressive mood or sadness, loss of interest or pleasure, and fatigue or lack of energy. The symptoms associated with depression, according to the ICD-10 classification, are: - Sleep disorders, - Feelings of guilt and worthlessness, - Decreased self-esteem and confidence, - Difficulties concentrating, - Disturbed appetite, - Decreased libido, - Suicidal thoughts or acts, - Agitation or slowing of movement or speech, - Weight loss, - Symptoms of anxiety or nervousness. More recently, the guidelines of the World Federation of Societies of Biological Psychiatry and the Canadian Network for Mood and Anxiety Treatments Taskforce indicate that St. John's wort is recommended as monotherapy for mild to moderate forms of major depressive disorders.
Posologie
Oral: flowering tops
900 - 1800 mg
6 - weeks
mother tincture, standardized extract
St. John's wort for depression: an overview and meta-analysis of randomized clinical trials.
Comparison of equivalence between the St. John's wort extract LoHyp-57 and fluoxetine.
Equivalence of St. John's wort extract (Ze 117) and fluoxetine: a randomized, controlled study in mild-moderate depression.
A systematic review of newer pharmacotherapies for depression in adults: Evidence report summary.
St. John's wort for depression: A meta-analysis of well-defined clinical trials.
Hypericum treatment of mild depressions with somatic symptoms.
LI 160, an extract of St. John's wort, versus amitriptyline in mildly to moderately depressed outpatients - a controlled 6-week clinical trial.
Acute treatment of moderate to severe depression with hypericum extract WS 5570 (St John's wort): randomised controlled double blind non-inferiority trial versus paroxetine.
Hypericum extract versus imipramine or placebo in patients with moderate depression: randomized multicentre study of treatment for eight weeks.
Open-label pilot study of St. John's wort in adolescent depression.
Controlled clinical trials of hypericum extracts in depressed patients - an overview.
E/S/C/O/P: 2nd Edition of the ESCOP Monographs
Clinician guidelines for the treatment of psychiatric disorders with nutraceuticals and phytoceuticals: The World Federation of Societies of Biological Psychiatry (WFSBP) and Canadian Network for Mood and Anxiety Treatments (CANMAT) Taskforce
St John's wort for depression.
St. John's wort for depression.
Comparison of an extract of Hypericum (LI 160) and sertraline in the treatment of depression: A double-blind, randomized pilot study.
Efficacy and tolerability of St. John's wort extract LI 160 versus imipramine in patients with severe depressive episodes according to ICD-10
Emotional Balance ✪✪✪✪✪
Preliminary clinical research shows that the extract of St. John's wort might help combat seasonal affective disorders. St. John's wort seems to improve symptoms of anxiety, decreased libido, and sleep disorders associated with seasonal depression. Moreover, the EMA recognizes the use of St. John's wort as a traditional herbal medicine for the relief of temporary mental exhaustion, for supportive treatment of nervous agitation and sleep disorders. St. John's wort can be taken in the form of a dry extract or herbal tea: 2 to 3 g of the crushed plant substance in 150 ml of boiling water as an infusion, 2 times a day.
Posologie
Oral: flowering tops
180 - 1000 mg
2 - weeks
mother tincture, standardized extract
European Union herbal monograph on Hypericum perforatum L., herba (traditional use)
St John's Wort Extract (LI 160) in Somatoform Disorders: Results of a Placebo-Controlled Trial
Treatment of Somatoform Disorders With St. John's Wort: A Randomized, Double-Blind and Placebo-Controlled Trial
Hypericum in Seasonal Affective Disorder (SAD)
E/S/C/O/P: 2nd Edition of the ESCOP Monographs
Menopause ✪✪✪✪✪
Several studies with St. John's wort extracts significantly reduced the frequency, severity, and duration of hot flashes compared to a placebo in premenopausal, perimenopausal, and postmenopausal women. Women in the extract group reported significantly better quality of life with fewer sleep problems compared to placebo. The effectiveness on menopause symptoms seems more significant from week 4. St. John's wort has proven to be significantly superior to placebo in a meta-analysis comparing the efficacy and side effects of St. John's wort extracts, combined products, and placebo in menopausal women. The extracts contained 0.2 mg/ml of hypericin, taken at 20 drops three times a day or 405 to 900 mg of St. John's wort in three doses, per day.
Posologie
Oral: flowering tops
400 - 900 mg
5 - weeks
mother tincture, standardized extract
Hypericum perforatum preparations L. preparations for menopause: a meta-analysis of efficacy and safety.
Effects of Hypericum perforatum (St. John's wort) on hot flashes and quality of life in perimenopausal women: a randomized pilot trial.
Skin Healing ✪✪✪✪✪
St. John's wort is recognized for its soothing and healing properties. Traditionally, St. John's wort oil is obtained by macerating fresh flowering tops in vegetable oil, often olive oil, exposed to light for several days or weeks. The EMA recognizes St. John's wort as a traditional medicine used for the symptomatic treatment of minor skin inflammations, such as sunburn, as well as to support the healing of minor wounds. Some clinical studies support these uses. In a randomized double-blind clinical trial (n=144), ointments containing either an oil extract of St. John's wort (20%) or a placebo were applied topically on surgical wounds three times a day for 16 days, starting 24 hours after the cesarean section. An additional control group remained without any postoperative intervention. Compared to the placebo and control groups, significant improvements were observed in the group using the St. John's wort extract for wound healing on the 10th day and for scar formation on the 40th day postpartum.
Posologie
Topical: flowering tops
1 - weeks
ointment, cream, oil
Dermatoses ✪✪✪✪✪
In a randomized, placebo-controlled, double-blind study, 21 patients with mild to moderate atopic dermatitis were treated for 4 weeks with a cream containing St. John's Wort (1.5% hyperforin) or a placebo. The cream was applied twice daily. Results showed a significant improvement in eczema and a reduction in the presence of Staphylococcus aureus on the skin. Furthermore, the EMA recognizes St. John's Wort as a traditional treatment for mild skin inflammations, such as sunburns, and to promote healing of small wounds.
Posologie
Topically: flowering tops
1 - weeks
ointment, cream, oil
Attention Deficit Disorders ✪✪✪✪✪
A small open study shows that taking 30 mg of St. John's Wort daily for 4 weeks improves inattention, immaturity, and hyperactivity in adolescents with ADHD. However, other clinical research shows that taking a specific St. John's Wort extract standardized to 0.3% hypericin, at 300 mg three times daily for 8 weeks, does not significantly improve ADHD symptoms compared to placebo in children aged 6 to 17 years. Further studies are needed to confirm these results.
Posologie
Orally: flowering tops
30 mg
4 - weeks
Adolescents
mother tincture, standardized extract
Premenstrual Syndrome ✪✪✪✪✪
Some preliminary clinical evidence shows that a standardized extract of St. John's Wort 900 mg, taken in two to three divided doses per day for two menstrual cycles, reduces PMS symptoms, including insomnia, coordination issues, confusion, crying spells, headaches, and fatigue, as well as physical symptoms such as cravings and bloating by 40 to 51% compared to pretreatment. Other evidence shows that St. John's Wort extract containing hypericin at a dose of 1.36 mg per day for two menstrual cycles may reduce PMS symptoms including anxiety, depression, forgetfulness, headaches, and fatigue, compared to placebo. However, some clinical research shows that taking 600 mg of St. John's Wort (standardized to contain 1.8 mg hypericin) does not reduce anxiety or other PMS symptoms compared to placebo. The St. John's Wort extracts used were standardized for hypericin 0.18% and hyperforin 3.38%.
Posologie
Orally: flowering tops
600 - 900 mg
2 - months
mother tincture, standardized extract
Anxiety ✪✪✪✪✪
St. John's Wort might help relieve anxiety disorder. Taking a compound containing 100 mg of St. John's Wort and 50 mg of valerian root for two weeks reduces moderate to severe anxiety in more patients than 2 mg diazepam.
Posologie
Orally: flowering tops
200 - 900 mg
2 - weeks
mother tincture, standardized extract
Synergies
Smoking Cessation ✪✪✪✪✪
In an open study on St. John's Wort, conducted with 24 smokers, taking 900 mg per day for 3 months was associated with a smoking abstinence rate of 24% at the end of the treatment. However, other preliminary evidence shows that taking a St. John's Wort extract at a dose of 300 mg once or twice daily starting one week before and for three months during smoking cessation does not improve continuous abstinence rates compared to placebo. The GABAergic properties of St. John's Wort justify its use in withdrawal situations (tobacco, alcohol), but more studies are needed for conclusive evidence.
Posologie
Orally: flowering tops
600 - 900 mg
3 - months
mother tincture, standardized extract
Psoriasis ✪✪✪✪✪
Preliminary clinical research shows that applying an ointment containing a 5% extract of St. John's Wort twice daily for 4 weeks reduces the severity, size, thickness, and degree of erythema of psoriasis plaques compared to placebo or no treatment. Furthermore, the EMA recommends St. John's Wort in the symptomatic treatment of minor skin inflammations and as an aid in healing minor wounds.
Posologie
Topically: flowering tops
1 - weeks
ointment, cream, oil
Topical Application of St. John's Wort (Hypericum Perforatum)
The Impact of Topical Saint John's Wort ( Hypericum perforatum) Treatment on Tissue Tumor Necrosis Factor-Alpha Levels in Plaque-Type Psoriasis: A Pilot Study
Herpes ✪✪✪✪✪
Preliminary research shows that applying a single dose of a topical product containing 0.10% St. John's Wort and 5% copper sulfate pentahydrate helps reduce symptoms such as tingling and burning, erythema, and pain in patients with herpes simplex virus 1 (HSV-1) or 2 (HSV-2). In fact, the combined product seems to reduce erythema, itching, and pain in more patients than Acyclovir 5% applied five times daily for 7 days. Acyclovir is an antiviral medication, effective against herpes virus group, used for cold sores and genital herpes.
Posologie
Topically: flowering tops
1 - weeks
ointment, cream, oil
Synergies
Digestion Disorders ✪✪✪✪✪
St. John's Wort is traditionally recommended for the symptomatic relief of mild gastrointestinal discomfort. As a tea: 2 g of crushed herbal substance in 150 ml of boiling water, infused, twice a day.
Posologie
Orally: flowering tops
2 g
1 - weeks
tea/infusion
Properties
Antidepressant
St. John's Wort acts against depression by affecting several key neurotransmitters. Its components, hyperforin and adhyperforin, modulate the effects of serotonin, dopamine, and norepinephrine by inhibiting their reuptake. Moreover, St. John's Wort acts as an antagonist of serotoninergic receptors 5-HT3 and 5-HT4 and down-regulates certain beta-adrenergic and serotoninergic receptors with prolonged use. These interactions with neurotransmitters can cause a dose-dependent increase in cortisol. St. John's Wort also affects other neurotransmitters related to depression, such as glutamate and GABA. Hypericin, another constituent, inhibits certain enzymes and receptors, thereby contributing to the antidepressant effect. It is important to note that the effect on serotonin is often considered the primary mechanism of its antidepressant action. The relationship between these neurotransmitters and depression is complex. To simplify, serotonin, often linked to the regulation of mood, sleep, and appetite, is generally decreased in depressed individuals. Dopamine, associated with motivation and pleasure, is also often affected in depression. Norepinephrine, which plays a role in attention and stress response, may also be imbalanced. An imbalance in these neurotransmitters is often targeted by antidepressant treatments to help restore their normal function and improve depression symptoms.
Usages associés
Anti-inflammatory
St. John's Wort has anti-inflammatory properties due to active compounds such as hyperforin and hypericin. Hyperforin, one of the main constituents of St. John's Wort, has demonstrated the ability to modulate several aspects of inflammation. It positively influences the production of certain substances such as IL-8, involved in recruiting immune cells to sites of inflammation, and ICAM-1, essential in cell communication within the immune system. These actions, combined with the regulation of important signaling pathways like AP-1 and ERK1/2, underscore its role in modulating inflammatory response. Furthermore, hyperforin has an effect on tryptophan, an amino acid, by reducing its degradation. Additionally, it acts on calcium regulation and the reduction of reactive oxygen species, important factors in inflammatory processes. Hypericin, another component of St. John's Wort, also contributes to its anti-inflammatory action by inhibiting the accumulation of NF-kappaB, a key regulator of inflammation, and by modifying the levels of certain proteins involved in inflammatory responses. Previous research has established that St. John's Wort also acts as a powerful inhibitor of opioid receptors, involved in pain perception, and modulates the expression of COX-2, a key enzyme in inflammatory processes. The efficacy of St. John's Wort in managing pain and inflammation is therefore supported by a variety of mechanisms.
Usages associés
Anticancer
Hyperforin may have activity against cancer cells. It appears to inhibit the growth of various types of cancer cells, including leukemia and glioma cell lines, by inducing apoptosis. Hyperforin targets molecules involved in signaling pathways controlling proliferation, survival, apoptosis, migration, and angiogenesis of leukemia cells. Additionally, it negatively regulates the expression of P-glycoprotein, a protein involved in leukemia cells' resistance to chemotherapeutic agents. Interestingly, preliminary clinical research has shown that taking hypericin in doses of 0.05-0.50 mg/kg for up to 3 months can reduce the size of gliomas in patients with recurrent malignant gliomas.
Antioxidant
The free radical scavenging activity of St. John's Wort is correlated with its flavonoid constituents, particularly hyperoside and quercetin.
Immunomodulator
An immunosuppressive effect of hypericin was found in vitro by inhibiting the release of arachidonic acid and interleukin-6, leukotriene B4, and the production of interleukin-1-alpha. An effect, including inhibition of T-cell proliferation, has been observed in vitro and in vivo in response to St. John's Wort.
Dermatological Effect
Topical preparations of St. John's Wort are considered beneficial for inflammatory skin conditions and superficial wounds by inhibiting the inflammatory response of the epidermis. It is likely that hypericin and hyperforin both contribute to this effect. High levels of tumor necrosis factor-alpha (TNF-alpha) found in the plasma and skin of individuals with psoriasis are significantly reduced by treatment with a 5% St. John's Wort ointment for 4 weeks. A case report also shows that St. John's Wort can improve the healing of pressure ulcers by enhancing scar formation.
Usages associés
Neurological
Quercetin, kaempferol, and biapigenin significantly reduced chemically induced neuronal death in hippocampal neurons from rat embryos. Neuroprotection was correlated with the prevention of delayed calcium deregulation and the maintenance of mitochondrial transmembrane electrical potential in the brain. The compounds reduced lipid peroxidation and transmembrane electrical potential loss caused by oxidative stress. On another hand, hypericin has been demonstrated to interfere with the early stages of the polymerization process responsible for neurodegenerative disorders. Other studies have shown that hyperforin and quercetin could be involved in the neuroprotective action of standardized St. John's Wort extracts, which could benefit elderly depressed patients suffering from degenerative disorders.
Usages associés
Antibacterial
St. John's Wort and its constituents, especially hypericin, have activity against viruses and bacteria, including the influenza virus, herpes simplex virus types I and II, Sindbis virus, poliovirus, retrovirus, hepatitis C, and Gram-negative and Gram-positive bacteria. Hyperforin can inhibit the growth of penicillin-resistant Staphylococcus aureus and other Gram-positive organisms, but not Gram-negative organisms.
Usages associés
Antiviral
The substances hypericin and pseudohypericin, present in St. John's wort, have been identified as having antiretroviral activity in vitro studies and animal models. However, it is important to stress that two clinical trials have not confirmed these effects in humans, even at high doses of hypericin. The exact mechanism by which hypericin acts against retroviruses remains mysterious. It is suspected that its action could be related to the direct inactivation of the virus, or to the prevention of its release, budding, or assembly at the cellular membrane level. An interesting point to note is that the presence of light appears to be a necessary condition for the antiretroviral activity of hypericin to be effective, as its effect seems to be photoactivated. In human research, a combined topical product containing copper sulfate pentahydrate and St. John's wort has demonstrated effectiveness in improving symptoms of herpetic lesions such as pain and erythema.
Usages associés
Safety dosage
Adults from 12 years: 180 mg - 1000 mg
The efficacy of St. John's Wort is dose-dependent and progressive. It is not advisable to abruptly stop St. John's Wort treatment; doses should be gradually reduced over one to two weeks to avoid withdrawal syndrome.
Children from 6 up to 12 years: 30 mg - 900 mg
Children 6 to 12 years under medical supervision only.
Interactions
Médicaments
Triptans: moderate interaction
The concurrent use of St. John's Wort and serotonin agonists could increase serotonergic effects. Concomitant use should be avoided.
Alprazolam: strong interaction
St. John's Wort may decrease the effect of alprazolam. Alprazolam, used as a probe for cytochrome P450 3A4 (CYP3A4) activity, has a twofold higher clearance when administered with St. John's Wort. St. John's Wort reduces alprazolam's half-life from 12.4 hours to 6 hours.
Aminolevulinic Acid: moderate interaction
Concomitant use with St. John's Wort extract may cause synergistic phototoxicity. Delta-aminolevulinic acid (an experimental drug used in oncological diagnostic procedures) may cause a burning erythematous rash and significant swelling of the face, neck, and hands when taken with St. John's Wort.
Antidepressant: moderate interaction
Simultaneous use may lead to increased serotonin production and induce serotonin syndrome.
Sedatives: moderate interaction
St. John's Wort may reduce the duration of effect (sleep) produced by the use of barbiturates.
P450 cytochrome substrate: strong interaction
St. John's Wort, a hepatic enzyme inducer, acts on the P450 cytochrome, and by inducing P-glycoprotein P40,41, causes drug interactions with medications like cyclosporine, anti-cancer drugs (including protease inhibitors), digoxin, nifedipine, simvastatin, midazolam, anti-migraines, bronchodilators.
Oral contraceptives: strong interaction
St. John's Wort can reduce norethindrone and ethinylestradiol levels by 13 to 15%, leading to significant bleeding, irregular menstrual bleeding, or unplanned pregnancy. Irregular bleeding generally occurs in the week following the start of St. John's Wort treatment, and regular cycles typically return when St. John's Wort treatment is stopped. An unplanned pregnancy has occurred when using oral contraceptives and St. John's Wort extract simultaneously.
Cyclosporine: strong interaction
Concomitant use may reduce plasma cyclosporine levels by 30% to 70%. The use of St. John's Wort with cyclosporine in patients who have undergone heart, renal, or hepatic transplantation may cause subtherapeutic cyclosporine levels and acute graft rejection. This interaction occurred with a standardized St. John's Wort extract of 0.3% hypericin, dosed at 300-600 mg per day. Withdrawal of St. John's Wort may lead to a 64% increase in cyclosporine levels. St. John's Wort induces cytochrome P450 3A4 (CYP3A4), which increases cyclosporine clearance.
Digoxin: strong interaction
St. John's Wort may reduce the bioavailability, serum levels, and therapeutic effects of digoxin, necessitating dosage adjustments when starting or stopping St. John's Wort. Oral intake of a St. John's Wort extract, 900 mg containing hyperforin 7.5 mg or more per day for 10-14 days, can reduce digoxin serum levels by 25% in healthy individuals. It is thought that St. John's Wort affects the multi-drug transporter, P-glycoprotein, involved in absorption and elimination of digoxin and other drugs. St. John's Wort products providing less than 7.5 mg of hyperforin per day do not appear to affect digoxin levels.
Docetaxel: strong interaction
Clinical research shows that taking a specific St. John's Wort product at a dose of 300 mg three times daily for 14 days increases docetaxel clearance by approximately 14%, resulting in decreased plasma concentration of docetaxel in cancer patients. This is most likely due to the inductive effect of St. John's Wort on cytochrome P450 3A4 (CYP3A4). Taking St. John's Wort with docetaxel may reduce the efficacy of docetaxel in cancer treatment.
Fenfluramine: strong interaction
Concomitant use of St. John's Wort may increase the risk of serotonergic side effects and symptoms similar to serotonin syndrome. Administration of 600 mg of St. John's Wort per day with fenfluramine may cause nausea, headaches, and anxiety.
Fexofenadine: moderate interaction
St. John's Wort reduces the elimination of Fexofenadine.
Gliclazide: moderate interaction
St. John's Wort accelerates the elimination of Gliclazide, potentially decreasing its hypoglycemic effect.
Statins: moderate interaction
St. John's Wort accelerates the elimination of statins, thus decreasing their effects.
Meperidine: moderate interaction
The concurrent use may enhance serotonergic effects.
Methadone: moderate interaction
St. John's Wort reduces the efficacy of methadone by lowering its blood concentration.
Imatinib: strong interaction
Taking 900 mg of St. John's Wort per day for 2 weeks reduces the bioavailability and half-life of a single dose of Imatinib, decreasing its serum levels by 30% in healthy volunteers. This is most likely due to St. John's Wort's inductive effect on cytochrome P450 3A4 (CYP3A4), which increases Imatinib clearance. Advise patients not to take St. John's Wort if they are taking Imatinib.
Irinotecan: strong interaction
Concomitant use with St. John's Wort may reduce the efficacy of Irinotecan. St. John's Wort, at doses of 900 mg per day for 18 days, reduces the serum levels of Irinotecan by at least 50%.
Ketamine: strong interaction
Taking 300 mg of St. John's Wort three times daily for 14 days can significantly reduce the maximum serum levels of ketamine by about 66%. This is most likely due to St. John's Wort's inductive effect on cytochrome P450 3A4 (CYP3A4). Theoretically, taking St. John's Wort with ketamine could diminish ketamine's analgesic effects.
Non-nucleoside reverse transcriptase inhibitor: strong interaction
Concomitant use may reduce serum levels of NNRTIs. St. John's Wort can increase the oral clearance of nevirapine by 35%. Subtherapeutic concentrations are associated with therapeutic failure, development of viral resistance, and class-wide drug resistance. St. John's Wort induces intestinal and hepatic cytochrome P450 3A4 (CYP3A4) and intestinal P-glycoprotein/MDR-1, a drug transporter. Other NNRTIs include etravirine, delavirdine, and efavirenz.
Omeprazole: strong interaction
Taking St. John's Wort, 300 mg orally three times daily for 14 days, reduces serum concentrations of omeprazole by inducing its metabolism via cytochromes P450 2C19 and 3A4 (CYP2C19, CYP3A4). The extent of reduction in serum concentrations of omeprazole depends on the person's CYP2C19 genotype; it can reach up to 50% in extensive metabolizers and 38% in poor metabolizers.
Oxycodone: strong interaction
St. John's Wort may increase the metabolism of oxycodone by inducing cytochrome P450 3A4 (CYP3A4), reducing plasma levels and analgesic activity.
P-GLYCOPROTEIN substrate: strong interaction
St. John's Wort induces P-glycoprotein. P-glycoprotein is a carrier mechanism responsible for the transport of drugs and other substances across cell membranes. When P-glycoprotein is induced in the gastrointestinal tract, it can prevent the absorption of certain medications. Moreover, the induction of P-glycoprotein can decrease drug entry into the central nervous system (CNS) and reduce access to other sites of action. Drugs that may be affected include certain chemotherapeutic agents (etoposide, paclitaxel, vinblastine, vincristine, vindesine), antifungals (ketoconazole, itraconazole), protease inhibitors (amprenavir, indinavir, nelfinavir, saquinavir), H2 antagonists (cimetidine, ranitidine), certain calcium channel blockers (diltiazem, verapamil), corticosteroids, erythromycin, cisapride (Propulsid), fexofenadine (Allegra), cyclosporine, loperamide (Imodium), quinidine, and others.
Phenobarbital: strong interaction
St. John's Wort can increase the metabolism of phenobarbital, leading to a loss of seizure control. Plasma concentrations of phenobarbital should be closely monitored. The dose of phenobarbital may need to be increased when St. John's Wort is started and decreased when it is stopped.
Platelet Aggregation Inhibitors/Anticoagulant: strong interaction
The use of St. John's Wort significantly increases the clearance of warfarin. Moreover, simultaneous intake of warfarin and St. John's Wort can reduce the bioavailability of warfarin.
Protease Inhibitor: strong interaction
Concomitant use may reduce serum concentrations of PIs. Theoretically, St. John's Wort could also affect other antiretroviral medications of the PI type, including amprenavir, nelfinavir, ritonavir, and saquinavir. St. John's Wort also induces P-glycoprotein, which can lead to decreased intracellular protease inhibitor concentrations and increased elimination.
Tacrolimus: strong interaction
Taking St. John's Wort extract at a dose of 600 mg per day significantly reduces serum levels of tacrolimus. A dose increase of 60% may be necessary to maintain therapeutic levels of tacrolimus in patients taking St. John's Wort at the same time. It is believed that St. John's Wort lowers tacrolimus levels by inducing cytochrome P450 3A4 (CYP3A4) enzymes.
Warfarin: strong interaction
St. John's Wort may decrease the therapeutic effects of warfarin. Taking St. John's Wort significantly increases the clearance of warfarin. Taking warfarin simultaneously with St. John's Wort could reduce the bioavailability of warfarin.
Antiepileptics: strong interaction
St. John's Wort can increase the metabolism of phenobarbital and phenytoin, which may lead to reduced efficacy of these drugs.
Photosensitizers: moderate interaction
St. John's Wort may increase photosensitivity reactions due to its hypericin content. Theoretically, St. John's Wort could increase the possibility of photosensitivity reactions when used in combination with photosensitizing drugs. Photosensitizing drugs include naproxen, amiodarone, amitriptyline, ciprofloxacin, levofloxacin, moxifloxacin, trimethoprim/sulfamethoxazole, tetracycline, methoxsalen, glipizide, lamotrigine, and others.
Plantes ou autres actifs
St. John's Wort: weak interaction
St. John's Wort would theoretically reduce iron absorption.
St. John's Wort: weak interaction
Among the drugs whose action or toxicity is altered by St. John's Wort, there are most heart disorder medications. Theoretically, hawthorn is concerned.
Precautions
Alzheimer’s Disease: caution
St. John's Wort may induce psychosis in patients with Alzheimer's dementia. A case of psychotic delirium was reported three weeks after starting a low dose (75 mg per day) of St. John's Wort extract standardized to 0.3% hypericin. Symptoms disappeared several days after stopping St. John's Wort and starting Alzheimer’s treatment. St. John's Wort may contribute to worsening dementia in Alzheimer's patients.
Bipolar Disorder: avoid
St. John's Wort may trigger hypomania or mania when used in patients with bipolar disorder or depressed patients with bipolar disorder. In some cases, the manic episode appeared after two to eight weeks of St. John's Wort treatment and was effectively managed by reducing the St. John's Wort dose and increasing mood stabilizers like lithium.
Infertility: caution
Preliminary evidence suggests that St. John's Wort may inhibit oocyte fertilization and alter sperm DNA. This effect has not been demonstrated in humans, and animal studies suggest that St. John's Wort does not negatively impact fertility or gestation. However, caution is essential when used by couples trying to conceive, or it should be avoided entirely by those facing conception difficulties.
Surgical Intervention: avoid
St. John's Wort may cause cardiovascular collapse during anesthesia. St. John's Wort, used chronically for six months, appears to be the cause of severe hypotension following induction of anesthesia in an otherwise healthy patient. Theoretically, St. John's Wort could interfere with surgical procedures due to serotonergic effects on the central nervous system or vascular system. It is recommended to discontinue St. John's Wort at least two weeks prior to surgical procedures.
Schizophrenia: avoid
St. John's Wort could induce psychosis in patients with schizophrenia. There are two cases of relapse in non-medicated schizophrenic patients in remission who started taking St. John's Wort. Psychotic symptoms were resolved with the administration of antipsychotics and the cessation of St. John's Wort intake.
UV exposure: use with caution
Both topical and chronic oral use of St. John's Wort can cause significant photodermatitis. Women appear to be at higher risk of photosensitivity. Symptoms have been reported as mild to moderate and relieved after 12-16 days following treatment cessation. Fair-skinned individuals should take protective measures against direct sunlight when using St. John's Wort topically or orally.
Contraindications
Pregnancy: prohibited
St. John's Wort may have a uterotonic action (essential oil). Further research in animal models indicates that constituents of St. John's Wort could have teratogenic effects.
Breastfeeding: prohibited
Infants of mothers taking St. John's Wort have an increased tendency to suffer from colic, drowsiness, and lethargy (hyperforin is excreted in breast milk).
