Drug interactions
Hydrochlorothiazide + Lily of the valley
Severity: Major
Hydrochlorothiazide and Lily of the valley: major interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Lily of the valley contains cardiac glycosides (e.g., convallatoxin) with digoxin-like activity. Thiazide-induced hypokalemia and hypomagnesemia increase myocardial sensitivity to these glycosides and raise the risk of arrhythmias.
What this interaction means in plain words
Hydrochlorothiazide and Lily of the valley can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Why it happens
Thiazide-induced potassium and magnesium depletion enhances cardiac glycoside toxicity (pharmacodynamic).
What to do
Avoid use of lily of the valley preparations; if exposure occurs, monitor serum potassium, magnesium and ECG and correct electrolyte deficits promptly.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Hydrochlorothiazide
Frequently asked questions
Can I take Hydrochlorothiazide with Lily of the valley?
MediHelp rates the interaction as major. Hydrochlorothiazide and Lily of the valley can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Lily of the valley contains cardiac glycosides (e.g., convallatoxin) with digoxin-like activity. Thiazide-induced hypokalemia and hypomagnesemia increase myocardial sensitivity to these glycosides and raise the risk of arrhythmias.
How serious is the interaction between Hydrochlorothiazide and Lily of the valley?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid use of lily of the valley preparations; if exposure occurs, monitor serum potassium, magnesium and ECG and correct electrolyte deficits promptly.
What other medicines interact with Hydrochlorothiazide?
MediHelp also lists interactions of Hydrochlorothiazide with, for example, Dofetilide, Amifostine, Amiodarone. The full list is on the Hydrochlorothiazide page.
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