Drug interactions
Fluphenazine + Hyoscyamine
Severity: Moderate
Fluphenazine and Hyoscyamine: 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
Hyoscyamine and fluphenazine both have anticholinergic activity, so combined use can cause dry mouth, constipation, urinary retention, tachycardia, blurred vision and confusion. Older patients and those with glaucoma or ileus are at greater risk.
What this interaction means in plain words
Fluphenazine and Hyoscyamine 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.
Fluphenazine belongs to Central Nervous System; Hyoscyamine belongs to Genitourinary.
Why it happens
Additive antimuscarinic pharmacodynamic effects.
What to do
Monitor for anticholinergic toxicity, particularly in older adults, and reduce the dose of hyoscyamine if needed. Avoid in patients with narrow-angle glaucoma or obstructive bowel or urinary conditions.
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?
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Other interactions of Fluphenazine
- Arsenic trioxide + Fluphenazine Contraindicated
- Dofetilide + Fluphenazine Contraindicated
- Fluphenazine + Ibutilide Contraindicated
- Fluphenazine + Pimozide Contraindicated
- Adagrasib + Fluphenazine Major
- Alfentanil + Fluphenazine Major
Other interactions of Hyoscyamine
- Amantadine + Hyoscyamine Moderate
- Amitriptyline + Hyoscyamine Moderate
- Aripiprazole + Hyoscyamine Moderate
- Atropine + Hyoscyamine Moderate
- Benztropine + Hyoscyamine Moderate
- Bethanechol + Hyoscyamine Moderate
Frequently asked questions
Can I take Fluphenazine with Hyoscyamine?
MediHelp rates the interaction as moderate. Fluphenazine and Hyoscyamine 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. Hyoscyamine and fluphenazine both have anticholinergic activity, so combined use can cause dry mouth, constipation, urinary retention, tachycardia, blurred vision and confusion. Older patients and those with glaucoma or ileus are at greater risk.
How serious is the interaction between Fluphenazine and Hyoscyamine?
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 for anticholinergic toxicity, particularly in older adults, and reduce the dose of hyoscyamine if needed. Avoid in patients with narrow-angle glaucoma or obstructive bowel or urinary conditions.
What other medicines interact with Fluphenazine?
MediHelp also lists interactions of Fluphenazine with, for example, Arsenic trioxide, Dofetilide, Ibutilide. The full list is on the Fluphenazine page.
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