St. John's wort: benefits, dosage, contraindications
Other name(s)
St. John's wort
Scientific name(s)
Hypericum perforatum
Family or group:
Plants
Active ingredients:
Quercetin
Flavonoids
Hypericin
Hyperforin
Xanthophylls
Melatonin
Indications
Scoring methodology
EFSA approval.
Depression ✪✪✪✪✪
The efficacy and safety of standardized hydroalcoholic St. John's wort extracts have been evaluated in more than 50 double-blind, controlled trials involving 8,327 patients, and 15 open studies, post-marketing surveillance studies and numerous case reports involved a further 15,359 patients. The primary indication in most studies was mild depressive disorders or mild to moderate depressive disorders. A significant improvement in the core symptoms (mood, loss of interest and activity) and other symptoms of the 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 extracts standardized to 0.3% hypericin or 3 to 6% hyperforin. In order to characterize mild to moderate depression, ESCOP proposed the ICD-10, or International Classification of Diseases, 10th Revision. It is a classification system used in medicine 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 depressed mood or marked sadness, loss of interest or pleasure, and fatigue or loss of energy. The symptoms associated with depression, according to the ICD-10 classification, are: - Sleep disturbances, - Feelings of guilt and worthlessness, - Decreased self-esteem and self-confidence, - Difficulty 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 disorder.
Posologie
Oral administration: 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 St. John's wort extract may help combat seasonal affective disorders. St. John's wort appears to improve symptoms of anxiety, decreased libido and sleep disturbances associated with seasonal depression. Furthermore, the EMA recognizes the use of St. John's wort as a traditional herbal medicinal product for the relief of temporary mental exhaustion, for supportive treatment of nervous agitation and sleep disturbances. St. John's wort can be taken as a dry extract or as an herbal tea: 2 to 3 g of the crushed plant material in 150 ml of boiling water as an infusion, twice a day.
Posologie
Oral use: 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 with placebo in premenopausal, perimenopausal and postmenopausal women. Women in the extract group reported a significantly better quality of life with fewer sleep problems compared with placebo. The effectiveness on menopausal symptoms appears to be more pronounced from week 4 onward. St. John's wort was found to be significantly superior to placebo in a meta-analysis comparing the efficacy and adverse effects of St. John's wort extracts, combination products and placebo in menopausal women. The extracts contained 0.2 mg/ml hypericin, taken as 20 drops three times a day or 405 to 900 mg of St. John's wort in three doses per day.
Posologie
Orally: flowering tops
400 - 900 mg
5 weeks
mother tincture, standardized extract
Hypericum perforatum 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 the fresh flowering tops in a vegetable oil, often olive oil, exposed to light for several days or weeks. The EMA recognizes St. John's wort as a traditional medicinal product, used for the symptomatic treatment of minor inflammations of the skin, such as sunburn, as well as to support the healing of minor wounds.nnSome clinical studies corroborate these uses. In a randomized double-blind clinical trial (n=144), ointments containing either an oily extract of St. John's wort (20%) or a placebo were applied topically to surgical wounds three times a day for 16 days, starting 24 hours after cesarean section. An additional control group received no postoperative intervention. Compared with the placebo and control groups, significant improvements were observed in the group using the St. John's wort extract for wound healing on day 10 and for scar formation on day 40 postpartum.nn
Posologie
Topical use: 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 St. John's wort cream (1.5% hyperforin) or a placebo. This cream was applied twice daily. The results showed a significant improvement in eczema as well as a reduction in the presence of Staphylococcus aureus on the skin.nnFurthermore, the EMA recognizes St. John's wort as a traditional treatment for mild skin inflammations, such as sunburn, and to promote the healing of minor wounds.nn
Posologie
Topical: flowering tops
1 - weeks
ointment, cream, oil
Attention deficit disorders ✪✪✪✪✪
A small open study shows that taking 30 mg of St. John's wort per day 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 a dose of 300 mg three times a day for 8 weeks, does not significantly improve ADHD symptoms compared with placebo in children aged 6 to 17 years. nnFurther studies are needed to confirm these results.nn
Posologie
Oral: flowering tops
30 mg
4 - weeks
Adolescents
mother tincture, standardized extract
Premenstrual syndrome ✪✪✪✪✪
Some preliminary clinical evidence shows that a standardized 900 mg St John's wort extract, taken in two or three divided doses per day for two menstrual cycles, reduces PMS symptoms, including insomnia, impaired coordination, confusion, crying spells, headaches and fatigue, as well as physical symptoms such as cravings and bloating by 40 to 51% compared with 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 with placebo. However, some clinical research shows that taking 600 mg of St John's wort (standardized to contain 1.8 mg of hypericin) does not reduce anxiety or other PMS symptoms compared with placebo. The St John's wort extracts used were standardized to 0.18% hypericin and 3.38% hyperforin.
Posologie
Oral: flowering tops
600 - 900 mg
2 - months
mother tincture, standardized extract
Anxiety ✪✪✪✪✪
St John's wort may help relieve anxiety disorder. Taking a complex 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
Oral: 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 treatment. However, other preliminary evidence shows that taking a St. John's wort extract at 300 mg once or twice a day, starting one week before and continuing for three months after quitting smoking, does not improve the continuous abstinence rate compared with placebo. The GABAergic properties of St. John's wort explain its use for withdrawal in addiction situations (tobacco, alcohol), but more studies are needed to draw conclusions.
Posologie
Oral: flowering tops
600 - 900 mg
3 - months
mother tincture, standardized extract
Psoriasis ✪✪✪✪✪
Preliminary clinical research shows that applying an ointment containing a 5% St. John's wort extract twice daily for 4 weeks reduces the severity, size, thickness and degree of erythema of psoriasis plaques compared with placebo or no treatment. Furthermore, the EMA recommends St. John's wort for the symptomatic treatment of minor skin inflammations and as an aid to the healing of minor wounds.
Posologie
Topical: 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 the application of a single dose of a topical product containing St. John's wort at 0.10% and copper sulfate pentahydrate at 5% helps reduce symptoms such as tingling and burning, erythema and pain in patients infected with herpes simplex virus 1 (HSV-1) or 2 (HSV-2). In fact, the combined product appears to reduce erythema, itching and pain in more patients than 5% Acyclovir applied five times a day for 7 days. Acyclovir is an antiviral medication effective against viruses of the herpes group, recommended for cold sores and genital herpes.
Posologie
Topical use: flowering tops
1 - weeks
ointment, cream, oil
Synergies
Digestive disorders ✪✪✪✪✪
St. John's wort is traditionally recommended for the symptomatic relief of mild gastrointestinal discomfort. As an infusion: 2 g of crushed plant material in 150 ml of boiling water, infused, twice a day.
Posologie
Oral use: flowering tops
2 g
1 - weeks
herbal tea/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. In addition, St. John's wort acts as an antagonist of the serotonergic 5-HT3 and 5-HT4 receptors, and downregulates certain beta-adrenergic and serotonergic 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 main 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 people with depression. Dopamine, associated with motivation and pleasure, is also often affected in depression. Norepinephrine, which plays a role in attention and the stress response, can also be imbalanced. An imbalance in these neurotransmitters is often targeted by antidepressant treatments to help restore their normal function and improve symptoms of depression.
Usages associés
Anti-inflammatory
St. John's wort has anti-inflammatory properties thanks to active compounds such as hyperforin and hypericin. Hyperforin, one of the main constituents of St. John's wort, has been shown to modulate several aspects of inflammation. It positively influences the production of certain substances such as IL-8, which is involved in recruiting immune cells to sites of inflammation, and ICAM-1, which is essential for cell-to-cell communication within the immune system. These actions, combined with the regulation of key signaling pathways such as AP-1 and ERK1/2, underscore its role in modulating the inflammatory response. Furthermore, hyperforin affects tryptophan, an amino acid, by reducing its degradation. In addition, it influences 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 the anti-inflammatory action by inhibiting the accumulation of NF-kappaB, a key regulator of inflammation, and by altering the levels of certain proteins involved in inflammatory responses. Previous research has established that St. John's wort also acts as a potent inhibitor of opioid receptors, which are involved in pain perception, and modulates the expression of COX-2, a key enzyme in inflammatory processes. Thus, the effectiveness of St. John's wort in managing pain and inflammation is 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 leukemic cells. In addition, it downregulates the expression of P-glycoprotein, a protein involved in the resistance of leukemia cells to chemotherapeutic agents. Interestingly, preliminary clinical research has shown that taking hypericin at 0.05-0.50 mg/kg for a period of up to 3 months may reduce the size of gliomas in patients with recurrent malignant gliomas.
Antioxidant
The free radical-scavenging activity of St. John's wort correlates with its flavonoid constituents, notably hyperoside and quercetin.
Immunomodulatory
An immunosuppressive effect of hypericin has been observed in vitro, by inhibiting the release of arachidonic acid and interleukin-6, of leukotriene B4, and of interleukin-1 alpha production. An effect that included inhibition of T-cell proliferation was 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 epidermal inflammatory response. It is likely that both hypericin and hyperforin contribute to this effect. Elevated tumor necrosis factor alpha (TNF-alpha) levels found in the plasma and skin of people 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 may improve the healing of pressure ulcers by promoting wound repair.
Usages associés
Neurological
Quercetin, kaempferol, and biapigenin significantly reduced chemically induced neuronal death in hippocampal neurons from rat embryos. Neuroprotection was correlated with prevention of delayed calcium dysregulation and with maintenance of the mitochondrial transmembrane electrical potential in the brain. The compounds reduced lipid peroxidation and loss of mitochondrial transmembrane electrical potential caused by oxidative stress. On the other hand, hypericin has been shown to interfere with the early stages of the polymerization process responsible for neurodegenerative disorders. Other studies have shown that hyperforin and quercetin may be involved in the neuroprotective action of standardized St. John's wort extracts, which could benefit depressed elderly patients suffering from degenerative disorders.
Usages associés
Antibacterial
St. John's wort and its constituents, hypericin in particular, have activity against viruses and bacteria, notably 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
Hypericin and pseudohypericin, substances present in St. John's wort, have been identified as having antiretroviral activity in in vitro studies and in animal models. However, it is important to emphasize that two clinical trials did not confirm 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 may be related to direct inactivation of the virus, or to prevention of its release, budding, or assembly at the cell membrane. An interesting point to note is that the presence of light appears to be a necessary condition for hypericin's antiretroviral activity to be effective, since its effect seems to be photoactivated. In human research, a topical product combining copper sulfate pentahydrate and St. John's wort has been shown to be effective in improving symptoms of herpetic lesions such as pain and erythema.
Usages associés
Safe dosage
Adults from 12 years of age: 180 mg - 1000 mg
The effectiveness of St. John's wort is dose-dependent and progressive. It is not recommended to abruptly stop treatment with St. John's wort; doses should be gradually reduced over one to two weeks to avoid withdrawal syndrome.
Child aged 6 to 12 years: 30 mg - 900 mg
Children aged 6 to 12 years under medical supervision only.
Interactions
Médicaments
Triptans: moderate interaction
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 reduce the effect of alprazolam. Alprazolam, which is used as a probe for cytochrome P450 3A4 (CYP3A4) activity, has twice the clearance when administered with St. John's wort. St. John's wort reduces the half-life of alprazolam 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 oncologic diagnostic procedures) can cause a burning erythematous rash and marked swelling of the face, neck, and hands when taken with St. John's wort.
Antidepressant: moderate interaction
Concurrent use can increase serotonin production and lead to serotonin syndrome.
Sedatives: moderate interaction
St. John's wort may reduce the sedative effect (sleep) produced by the use of barbiturates.
Cytochrome P450 substrate: strong interaction
St. John's wort, a hepatic enzyme inducer, acts on the cytochrome P450 system and by inducing P-glycoprotein P40,41, causing drug interactions with certain medications such as cyclosporine, anticancer drugs (including protease inhibitors), digoxin, nifedipine, simvastatin, midazolam, antimigraine agents, and bronchodilators.
Oral contraceptives: strong interaction
St. John's wort can reduce norethindrone and ethinylestradiol levels by 13 to 15%, which can lead to heavy bleeding, irregular menstrual bleeding, or an unplanned pregnancy. Irregular bleeding usually occurs within the week after starting St. John's wort treatment and regular cycles generally return when St. John's wort treatment is discontinued. An unplanned pregnancy has occurred during concurrent use of oral contraceptives and St. John's wort extract.
Cyclosporine: strong interaction
Concurrent use may reduce cyclosporine plasma levels by 30% to 70%. Using St. Johns wort with cyclosporine in patients who have undergone heart, kidney, or liver transplantation can result in subtherapeutic cyclosporine levels and acute graft rejection. This interaction has occurred with a St. Johns wort extract standardized to 0.3% hypericin and dosed at 300-600 mg per day. Withdrawal of St. Johns wort can lead to a 64% increase in cyclosporine levels. St. Johns wort induces cytochrome P450 3A4 (CYP3A4), which increases the clearance of cyclosporine.
Digoxin: strong interaction
St. Johns wort may reduce the bioavailability, serum levels, and therapeutic effects of digoxin, which may necessitate dosage adjustments when St. Johns wort is started or stopped. Oral administration of a St. Johns wort extract, 900 mg containing 7.5 mg or more of hyperforin per day for 10-14 days, can reduce serum digoxin levels by 25% in healthy individuals. It is believed that St. Johns wort affects the multidrug transporter P-glycoprotein, which is involved in the absorption and elimination of digoxin and other drugs. St. Johns 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 300 mg three times a day for 14 days increases docetaxel clearance by about 14%, resulting in a decreased plasma concentration of docetaxel in cancer patients. This is most likely due to St. John's wort's inducing effect on cytochrome P450 3A4 (CYP3A4).nnTaking St. John's wort with docetaxel may reduce the effectiveness 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, and the hypoglycemic effect of gliclazide would be reduced.
Statins: moderate interaction
St. John's wort accelerates the elimination of statins and thus decreases their effects.
Meperidine: moderate interaction
Concurrent use would increase serotonergic effects.
Methadone: moderate interaction
St. John's wort reduces the effectiveness 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 and decreases its serum level by 30% in healthy volunteers. This is most likely due to St. John's wort's inducing 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
Concurrent use with St. John's wort may reduce the effectiveness of irinotecan. St. John's wort, at 900 mg per day for 18 days, reduces serum irinotecan levels by at least 50%.
Ketamine: strong interaction
Taking 300 mg of St. John's wort three times daily for 14 days can significantly reduce peak serum ketamine levels by about 66%. This is most likely due to St. John's wort's inducing effect on cytochrome P450 3A4 (CYP3A4). Theoretically, taking St. John's wort with ketamine could reduce ketamine's analgesic effects.
Non-nucleoside reverse transcriptase inhibitor: strong interaction
Concurrent use may reduce serum NNRTI levels. St. John's wort can increase the oral clearance of nevirapine by 35%. Subtherapeutic concentrations are associated with treatment failure, the development of viral resistance, and the development of resistance to the drug class. 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 a day for 14 days, reduces serum omeprazole concentrations by inducing its metabolism via cytochromes P450 2C19 and 3A4 (CYP2C19, CYP3A4). The degree of reduction in serum omeprazole concentrations depends on the person's CYP2C19 genotype; it can reach 50% in extensive metabolizers and 38% in poor metabolizers.
Oxycodone: strong interaction
St. John's wort may increase oxycodone metabolism 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 an efflux mechanism responsible for transporting drugs and other substances across cell membranes. When P-glycoprotein is induced in the gastrointestinal tract, it can prevent the absorption of certain drugs. In addition, 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), some calcium channel blockers (diltiazem, verapamil), corticosteroids, erythromycin, cisapride (Propulsid), fexofenadine (Allegra), cyclosporine, loperamide (Imodium), quinidine, and others.
Phenobarbital: strong interaction
St. John's wort may increase the metabolism of phenobarbital, resulting in loss of seizure control. Phenobarbital plasma concentrations should be closely monitored. It may be necessary to increase the dose of phenobarbital when St. John's wort is started and to decrease it when it is stopped.
Antiplatelet agents/Anticoagulant: strong interaction
The use of St. John's wort significantly increases the clearance of warfarin. In addition, concomitant use of warfarin and St. John's wort may reduce warfarin bioavailability.
Protease inhibitor: strong interaction
Concomitant use may reduce serum concentrations of PIs. Theoretically, St. John's wort could also affect other antiretroviral drugs of the PI class, including amprenavir, nelfinavir, ritonavir, and saquinavir. St. John's wort also induces P-glycoprotein, which may lead to decreased intracellular protease inhibitor concentrations and increased elimination.
Tacrolimus: strong interaction
Taking a St. John's wort extract at 600 mg per day markedly decreases serum tacrolimus levels. A dose increase of 60% may be necessary to maintain therapeutic tacrolimus levels in patients who take St. John's wort concurrently. St. John's wort is thought to lower 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 markedly increases the clearance of warfarin. Taking warfarin at the same time as St. John's wort could reduce the bioavailability of warfarin.
Antiepileptics: strong interaction
St. John's wort may increase the metabolism of phenobarbital and phenytoin, which may lead to a reduction in the effectiveness of these medications.
Photosensitizing agents: moderate interaction
St. John's wort could increase photosensitivity reactions due to its hypericin content. Theoretically, St. John's wort could increase the likelihood 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: low interaction
St. John's wort would theoretically reduce iron absorption.
St. John's wort: low interaction
Among the drugs whose action or toxicity is altered by St. John's wort are most medications for heart conditions. Theoretically, hawthorn may be affected.
Precautions
Alzheimer's disease: use with caution
St. John's wort could induce psychosis in patients with Alzheimer's dementia. A case of psychotic delirium was reported three weeks after the start of administration of a low dose (75 mg per day) of St. John's wort extract standardized to 0.3% hypericin. The symptoms disappeared several days after stopping St. John's wort and starting treatment for Alzheimer's disease. St. John's wort could contribute to worsening dementia in patients with Alzheimer's disease.
Bipolar disorder: avoid
St. John's wort can cause hypomania or mania when used in patients with bipolar disorder or in depressed patients with bipolar disorder. In some cases, the manic episode appeared after two to eight weeks of treatment with St. John's wort and was effectively managed by decreasing the dose of St. John's wort and increasing the dose of mood stabilizers such as lithium.
Infertility: use with caution
Preliminary evidence suggests that St. John's wort may inhibit oocyte fertilization and alter sperm DNA. This effect has not yet been demonstrated in humans, and animal studies suggest that St. John's wort does not have a negative effect on fertility or pregnancy. However, it is essential to be cautious when using it if couples are trying to conceive, or to avoid it completely in those who are experiencing conception problems.
Surgical intervention : avoid
St. John's wort can cause cardiovascular collapse during anesthesia. St. John's wort, used chronically for six months, appears to have been the cause of severe hypotension after induction of anesthesia in an otherwise healthy patient. Theoretically, St. John's wort could interfere with surgical procedures because of serotonergic effects on the central nervous system or the vascular system. It is recommended to stop using St. John's wort at least two weeks before surgical procedures.
Schizophrenia : avoid
St. John's wort could induce psychosis in patients with schizophrenia. There are two cases of relapse in medication-free patients with schizophrenia who were in remission and began taking St. John's wort. The psychotic symptoms resolved with the administration of antipsychotics and discontinuation of St. John's wort
UV exposure : use with caution
Topical use and chronic oral use of St. John's wort can both cause significant photodermatosis. Women appear to be at higher risk of photosensitivity. Symptoms have been reported as mild to moderate and subsided 12-16 days after stopping treatment. Fair-skinned individuals should take protective measures against direct sunlight when using St. John's wort topically or orally.
Contraindications
Pregnant woman: prohibited
St. John's wort may have a uterotonic effect (from the essential oil). Other research in animal models shows that constituents of St. John's wort could have teratogenic effects.
Breastfeeding: prohibited
Infants of mothers who take St. John's wort are more likely to suffer from colic, drowsiness, and lethargy (hyperforin is excreted in breast milk).
