Drug interactions
Fosinopril-hydrochlorothiazide + Thioridazine
Severity: Moderate
Fosinopril-hydrochlorothiazide and Thioridazine: moderate 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
Thioridazine has alpha-blocking properties and can cause orthostatic hypotension, which may add to the blood-pressure lowering of fosinopril and hydrochlorothiazide. Thioridazine also prolongs the QT interval, and thiazide-induced hypokalemia or hypomagnesemia can increase the risk of torsades de pointes.
What this interaction means in plain words
Fosinopril-hydrochlorothiazide and Thioridazine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Fosinopril-hydrochlorothiazide belongs to Cardiovascular; Thioridazine belongs to Central Nervous System.
Why it happens
Additive hypotensive effects via alpha-adrenergic blockade, plus electrolyte disturbance from the thiazide that potentiates thioridazine QT prolongation.
What to do
Monitor blood pressure, especially on standing, and check potassium and magnesium regularly, correcting deficits. Obtain an ECG if other QT-prolonging factors are present.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Fosinopril-hydrochlorothiazide and Thioridazine, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
Other interactions of Fosinopril-hydrochlorothiazide
- Aliskiren + Fosinopril-hydrochlorothiazide Contraindicated
- Dofetilide + Fosinopril-hydrochlorothiazide Contraindicated
- Fosinopril-hydrochlorothiazide + Protein a column Contraindicated
- Fosinopril-hydrochlorothiazide + Sacubitril / valsartan Contraindicated
- Aldesleukin + Fosinopril-hydrochlorothiazide Major
- Amifostine + Fosinopril-hydrochlorothiazide Major
Other interactions of Thioridazine
- Abiraterone + Thioridazine Contraindicated
- Adagrasib + Thioridazine Contraindicated
- Amiodarone + Thioridazine Contraindicated
- Amisulpride + Thioridazine Contraindicated
- Amitriptyline + Thioridazine Contraindicated
- Amoxapine + Thioridazine Contraindicated
Frequently asked questions
Can I take Fosinopril-hydrochlorothiazide with Thioridazine?
MediHelp rates the interaction as moderate. Fosinopril-hydrochlorothiazide and Thioridazine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Thioridazine has alpha-blocking properties and can cause orthostatic hypotension, which may add to the blood-pressure lowering of fosinopril and hydrochlorothiazide. Thioridazine also prolongs the QT interval, and thiazide-induced hypokalemia or hypomagnesemia can increase the risk of torsades de pointes.
How serious is the interaction between Fosinopril-hydrochlorothiazide and Thioridazine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor blood pressure, especially on standing, and check potassium and magnesium regularly, correcting deficits. Obtain an ECG if other QT-prolonging factors are present.
What other medicines interact with Fosinopril-hydrochlorothiazide?
MediHelp also lists interactions of Fosinopril-hydrochlorothiazide with, for example, Aliskiren, Dofetilide, Protein a column. The full list is on the Fosinopril-hydrochlorothiazide page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
