Drug interactions
Phenylephrine po + Timolol
Severity: Moderate
Phenylephrine po and Timolol: 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
Oral phenylephrine is an alpha-1 agonist that raises blood pressure. In patients taking a nonselective beta-blocker such as timolol, vasoconstriction may go unopposed, and hypertensive episodes with reflex bradycardia are possible, although rare.
What this interaction means in plain words
Phenylephrine po and Timolol 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.
Why it happens
Pharmacodynamic synergism: beta-blockade removes vasodilatory opposition to alpha-1 mediated vasoconstriction.
What to do
Check blood pressure when oral phenylephrine decongestants are used with timolol, and prefer non-pressor alternatives in patients with hypertension.
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 Timolol
- Acebutolol + Timolol Major
- Albuterol + Timolol Major
- Aldesleukin + Timolol Major
- Amifostine + Timolol Major
- Amiodarone + Timolol Major
- Arformoterol + Timolol Major
Frequently asked questions
Can I take Phenylephrine po with Timolol?
MediHelp rates the interaction as moderate. Phenylephrine po and Timolol 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. Oral phenylephrine is an alpha-1 agonist that raises blood pressure. In patients taking a nonselective beta-blocker such as timolol, vasoconstriction may go unopposed, and hypertensive episodes with reflex bradycardia are possible, although rare.
How serious is the interaction between Phenylephrine po and Timolol?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check blood pressure when oral phenylephrine decongestants are used with timolol, and prefer non-pressor alternatives in patients with hypertension.
What other medicines interact with Timolol?
MediHelp also lists interactions of Timolol with, for example, Acebutolol, Albuterol, Aldesleukin. The full list is on the Timolol page.
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