Course 13: Botanical Medicine
Lesson 11 of 12. These notes synthesize uploaded historical botanical lectures with separately identified current safety guidance. Traditional uses are not evidence of clinical efficacy or a prescribing directive.
Medication reconciliation
- List prescriptions, OTC medications, supplements, alcohol, recreational products, recent starts and stops. Capture brand, botanical species, part, dose, manufacturer and batch, not just “herbal tea.”
Pharmacokinetic mechanisms
- St. John’s wort is a major inducer of CYP/P-glycoprotein pathways, reducing exposure to some contraceptives, transplant drugs, anticoagulants and other medicines. Goldenseal can inhibit drug-metabolizing enzymes and has been shown to lower metformin exposure in a study.
Pharmacodynamic mechanisms
- Sedative herbs may add to alcohol, benzodiazepines or hypnotics. Anticoagulant or antiplatelet exposure prompts a bleeding-risk screen. Licorice can affect blood pressure and potassium. Glucose-lowering drugs require a hypoglycemia safety plan.
Pregnancy, organ disease and surgery
- Screen pregnancy and lactation, age, liver or renal disease, cardiac arrhythmias, autoimmune conditions, surgery timing and prior allergic reactions. Kava products have been associated with rare, sometimes severe liver injury.
Practical response
- If risk is unknown or potentially significant, defer starting the botanical, contact prescriber/pharmacist, use product-level evidence, document informed consent, and monitor for unexpected loss of drug effect or toxicity.
Applied clinical case
A patient using warfarin and an oral contraceptive asks whether St. John’s wort is “safe because it is natural.” What should happen?
Show model reasoning and clinical disposition
Do not add it casually. It can decrease effectiveness of several medicines, with consequential outcomes. Obtain pharmacist/prescriber review and ensure appropriate contraception and anticoagulation follow-up.
Knowledge checks
- Describe CYP induction versus enzyme inhibition.
- Which patients need especially careful interaction review?
- What should be documented when an herb is stopped or started?
Source and safety links
- Health Canada: Natural Health Products (licensing, NPN, risk) (external)
- NCCIH: Herbs at a Glance (evidence and safety monographs) (external)
- NCCIH: Herb–Drug Interaction Evidence Digest (external)
- NCCIH: St. John’s Wort (external)
Downloadable study materials
- Botanical Safety and Toxicity Matrix (PDF)
- Formulation and Posology Worksheet (PDF)
- Herb-Drug Interaction Checklist (PDF)
- Botanical Herb and Action Reference (PDF)
- Complete Botanical Medicine Handbook (12 Lessons) (PDF)
- Exam-Focused Easy-Read Student Handbook (PDF)
- Botanical Medicine 300 MCQs with Explained Answers (PDF)