Online course: drug–supplement interactions
Warfarin, levothyroxine, antidepressants, statins: by drug class, you learn what happens, how serious it is, what to ask and what to do when a patient asks for a supplement.
What you learn
- Pharmacokinetics and pharmacodynamics, on classic examples
- Anticoagulants, antidiabetics, psychiatric drugs, immunosuppressants
- Severity: avoid, with monitoring, or separate in time
- How to check an interaction and what to do when data are missing
- Cases with patients on many medicines
Modules to start with
Drug–supplement interactions
By drug class: what happens, how serious it is, what to ask and what to do when counselling.
87 lessonsSafety: contraindications and interactions
Drug interactions, pregnancy, chronic disease and when to refer.
A few of the lessons
- How an interaction arises: pharmacokinetic or pharmacodynamic
- CYP3A4 and P-glycoprotein: why some herbs change drug levels
- Narrow therapeutic index drugs: where every interaction matters
- How to check an interaction: sources, level of evidence and missing data
- Medication history: the questions that uncover everything a patient takes
- Chelation: calcium, magnesium, iron, zinc and the spacing rule
- How to communicate an interaction: with the patient and with the doctor
- Warfarin and supplements: what moves the INR
The whole course: 904 lessons, in Romanian and English, for one year. See the full syllabus
What does your patient take? See what you check first.
Tap a medicine. A few classic examples from the interactions module.
Warfarin +
Lowers the anticoagulant effect. The INR (the clotting test) falls.
Opposes the effect. Steady intake matters, and any change calls for an INR check.
Possible bleeding risk, with mixed evidence. The doctor must know.
Direct anticoagulants +
May lower the drug level, and with it the protection against clots.
Added bleeding risk, with limited evidence. Ask the doctor first.
SSRI antidepressants +
Risk of serotonin syndrome: agitation, tremor, fever, sweating.
They add serotonin on top of the treatment. Same risk.
Levothyroxine +
They lower its absorption. Take them at least 4 hours apart.
May lower absorption. Coffee comes at least 30–60 minutes after the pill.
It does not change the treatment, but it can falsify the TSH test. Tell the lab.
Statins +
Raises simvastatin levels; with atorvastatin, large amounts matter. More muscle risk.
Monacolin K is lovastatin: in effect, the patient takes a second statin.
May lower the effect of some statins. Cholesterol rises for no obvious reason.
The pill +
Lowers hormone levels. Breakthrough bleeding and unplanned pregnancies are reported.
Antidiabetics +
Possible added effect, with variable evidence. The patient monitors, the doctor adjusts.
Metformin may lower it in the long term. Worth checking.
Quinolones, tetracyclines +
They bind the antibiotic in the gut. The exact gap is in the leaflet.
Educational examples for professionals, not a complete list. The patient does not stop or change a treatment alone. Sources: product information (SmPC), Stockley’s Drug Interactions, EMA/HMPC monographs, NIH ODS.
Frequently asked questions
Is it a complete list of interactions?
No. It teaches the mechanisms and the most important combinations. Always check the product information and reference sources.
What do I tell a patient if I find an interaction?
You do not advise them to stop treatment alone. The course practises how to explain it and refer to a doctor.
What level of knowledge does it need?
The lessons are made for pharmacists and pharmacy assistants, but start from the basics.