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★★☆Single study — solid evidence, such as one good trial or a large observational dataset, but not replicated at the top tier.
On an MAO inhibitor, phenylephrine can raise blood pressure sharply
Case reports describe systolic pressure rising more than 60 mmHg in people on MAO inhibitors, and the US tablet label forbids taking the two together.
What the study found
Reports on MAO inhibitors describe systolic rises above 60 mmHg
Reports of people taking phenylephrine while on a monoamine oxidase (MAO) inhibitor, a class of antidepressant, describe systolic pressure rising by more than 60 mmHg. The US label for 10 mg phenylephrine tablets forbids use with one, or within 2 weeks of stopping.
The caveat · Case reports, no count of how often
These are reports of individual cases gathered in a narrative review, so they show that it can happen, not how often.