?
★★★Well replicated — this finding’s sources average out to meta-analyses, systematic reviews or high-powered trials.
A week of phenylephrine has never been tested for blood pressure
A 2025 search for trials of oral decongestants taken daily for 7 days or more found none of phenylephrine that measured blood pressure.
What the study found
Nobody has measured blood pressure through a week of phenylephrine
A 2025 systematic search for placebo trials of oral decongestants taken daily for 7 days or more, with blood pressure measured, found none of phenylephrine. The dosing on its label, a tablet every 4 hours, has been checked for blood pressure only one dose at a time.
The caveat · Only other decongestants were tested
For the other oral decongestants pooled in that search, a week or more of daily use changed systolic pressure by 0.91 mmHg on average, at very low certainty. None of those trials used phenylephrine, so the figure cannot be carried over to it.