Drug interactions
Hyoscyamine + Pyridostigmine
Severity: Moderate
Hyoscyamine and Pyridostigmine: 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 blocks muscarinic receptors and is sometimes used deliberately to reduce pyridostigmine's gastrointestinal and secretory side effects. It will oppose those muscarinic effects but can mask early signs of cholinergic overdose and may add to anticholinergic effects such as constipation or urinary retention.
What this interaction means in plain words
Hyoscyamine and Pyridostigmine 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 belongs to Genitourinary; Pyridostigmine belongs to Central Nervous System.
Why it happens
Pharmacodynamic antagonism of muscarinic effects of acetylcholine accumulation.
What to do
Monitor muscle strength and for cholinergic crisis, and use the lowest effective hyoscyamine dose if given for side-effect control.
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 Pyridostigmine
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 Hyoscyamine with Pyridostigmine?
MediHelp rates the interaction as moderate. Hyoscyamine and Pyridostigmine 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 blocks muscarinic receptors and is sometimes used deliberately to reduce pyridostigmine's gastrointestinal and secretory side effects. It will oppose those muscarinic effects but can mask early signs of cholinergic overdose and may add to anticholinergic effects such as constipation or urinary retention.
How serious is the interaction between Hyoscyamine and Pyridostigmine?
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 muscle strength and for cholinergic crisis, and use the lowest effective hyoscyamine dose if given for side-effect control.
What other medicines interact with Pyridostigmine?
MediHelp also lists interactions of Pyridostigmine with, for example, Echothiophate iodide, Huperzine a, Neostigmine. The full list is on the Pyridostigmine page.
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