Can You Take st johns wort and warfarin Together?
Evidence-based clinical pharmacological assessment, adverse synergy evaluation, and administration separation protocols.
Co-administering st johns wort and warfarin has documented pharmacodynamic or pharmacokinetic antagonism capable of triggering acute clinical harm. Do not combine without explicit specialist oversight.
Clinical Mechanism & Evidence Details
Hyperforin potently induces hepatic CYP3A4 and intestinal P-gp, dramatically accelerating estrogen and progestin breakdown and causing contraceptive failure and unplanned pregnancies.
Additive inhibition of serotonin reuptake precipitates life-threatening Serotonin Syndrome (hyperthermia, autonomic rigidity, delirium, seizures).
Accelerated drug clearance drops serum drug levels below therapeutic range, triggering acute organ transplant rejection or fatal stroke/thromboembolism.
Vitamin K directly bypasses VKORC1 inhibition, rapidly dropping INR and triggering catastrophic stroke or thromboembolic events.
Additive antiplatelet and antithrombotic mechanisms significantly increase spontaneous internal and intracranial bleeding risks.
Inhibits intestinal CYP3A4-mediated first-pass metabolism, elevating systemic drug concentrations and increasing toxic adverse effect risks.
John’s wort can weaken the effects of many medicines, including crucially important medicines such as: Some antidepressants, including amitriptyline and bupropion Birth control pills Cyclosporine, which prevents the body from rejecting transplanted organs Some drugs used to prevent seizures, including phenytoin and carbamazepine Some heart medications, including digoxin and ivabradine Some HIV drugs, including indinavir and nevirapine Some cancer medications, including irinotecan, imatinib, and docetaxel Warfarin, an anticoagulant (blood thinner) Certain statins, including simvastatin In addition, taking St.
John’s wort can weaken the effects of many medicines, including crucially important medicines such as: Some antidepressants, including amitriptyline and bupropion Birth control pills Cyclosporine, which prevents the body from rejecting transplanted organs Some drugs used to prevent seizures, including phenytoin and carbamazepine Some heart medications, including digoxin and ivabradine Some HIV drugs, including indinavir and nevirapine Some cancer medications, including irinotecan, imatinib, and docetaxel Warfarin, an anticoagulant (blood thinner) Certain statins, including simvastatin In addition, taking St.
Reported to interact with Antidepressants (SSRIs, SNRIs, MAOIs) in clinical studies.
John’s wort with certain antidepressants or other drugs that affect serotonin (a substance produced by some nerve cells) may lead to increased serotonin-related side effects, which can be serious.
John’s wort can weaken the effects of many medicines, including crucially important medicines such as: Some antidepressants, including amitriptyline and bupropion Birth control pills Cyclosporine, which prevents the body from rejecting transplanted organs Some drugs used to prevent seizures, including phenytoin and carbamazepine Some heart medications, including digoxin and ivabradine Some HIV drugs, including indinavir and nevirapine Some cancer medications, including irinotecan, imatinib, and docetaxel Warfarin, an anticoagulant (blood thinner) Certain statins, including simvastatin In addition, taking St.
John’s wort can weaken the effects of many medicines, including crucially important medicines such as: Some antidepressants, including amitriptyline and bupropion Birth control pills Cyclosporine, which prevents the body from rejecting transplanted organs Some drugs used to prevent seizures, including phenytoin and carbamazepine Some heart medications, including digoxin and ivabradine Some HIV drugs, including indinavir and nevirapine Some cancer medications, including irinotecan, imatinib, and docetaxel Warfarin, an anticoagulant (blood thinner) Certain statins, including simvastatin In addition, taking St.
Reported to interact with Anticonvulsants / seizure medications (Phenytoin, Carbamazepine) in clinical studies.
Reported to interact with Statins (Simvastatin, Atorvastatin) in clinical studies.
John’s wort can weaken the effects of many medicines, including crucially important medicines such as: Some antidepressants, including amitriptyline and bupropion Birth control pills Cyclosporine, which prevents the body from rejecting transplanted organs Some drugs used to prevent seizures, including phenytoin and carbamazepine Some heart medications, including digoxin and ivabradine Some HIV drugs, including indinavir and nevirapine Some cancer medications, including irinotecan, imatinib, and docetaxel Warfarin, an anticoagulant (blood thinner) Certain statins, including simvastatin In addition, taking St.
John’s wort can weaken the effects of many medicines, including crucially important medicines such as: Some antidepressants, including amitriptyline and bupropion Birth control pills Cyclosporine, which prevents the body from rejecting transplanted organs Some drugs used to prevent seizures, including phenytoin and carbamazepine Some heart medications, including digoxin and ivabradine Some HIV drugs, including indinavir and nevirapine Some cancer medications, including irinotecan, imatinib, and docetaxel Warfarin, an anticoagulant (blood thinner) Certain statins, including simvastatin In addition, taking St.
Eat a healthy diet. Some foods and beverages that contain vitamin K can affect how warfarin works. Ask your doctor or pharmacist for a list of foods that contain vitamin K. Eat consistent amounts of vitamin K-containing food on a week-to-week basis. Do not eat large amounts of leafy, green vegetables or certain vegetable oils that contain large amounts of vitamin K. Be sure to talk to your doctor before you make any changes in your diet. Talk to your doctor about eating grapefruit and drinking grapefruit juice while taking this medication. <div
Taking other supplements, foods, or medications with this pair?
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Clinical mechanism and interaction severity derived from openFDA Drug Structured Product Labeling (Section 7), NIH Office of Dietary Supplements (ODS), and NIH NCCIH clinical botanicals database.