This is a systematic review and meta-analysis of 32 randomised trials enrolling 47,332 people treated with tirzepatide or semaglutide for type 2 diabetes or obesity, searched to September 2025. It pooled reported adverse events related to raised and to low blood pressure, rather than measured blood pressure readings.
The two drugs separated clearly. Tirzepatide reduced hypertension-related adverse events (risk ratio 0.40, 95% CI 0.26-0.60) but raised hypotension-related ones (RR 2.45, 95% CI 1.35-4.45), and more so at higher doses (RR 2.58, 95% CI 1.38-4.81). Semaglutide was close to neutral on both: hypertension-related events RR 0.81 (95% CI 0.57-1.15) and hypotension-related events RR 1.39 (95% CI 0.81-2.36), neither reaching significance.
The practical consequence is a deprescribing question that is easy to miss. A patient starting tirzepatide who is already on two or three antihypertensives, losing weight steadily and eating less is being pushed towards low blood pressure from several directions at once. The falls, the dizziness on standing and the near-syncope then get attributed to the injection when the real problem is that the antihypertensive regimen has become too large for the patient. Older patients and those on diuretics or alpha blockers are the ones to watch.
- Record a sitting and a standing blood pressure before each tirzepatide dose escalation, not only at initiation
- Ask directly about light-headedness on standing, morning dizziness and near-falls at every dose step
- Review diuretic and alpha blocker doses first when blood pressure falls; these contribute most to postural symptoms
- Warn patients that reduced food and fluid intake in the first weeks compounds the effect, particularly in hot weather
- Do not stop tirzepatide for a falling blood pressure before trying a reduction in antihypertensive burden
The statistics, in plain English
These are pooled adverse event reports from trial safety databases, not blood pressure measurements, so they capture what investigators judged worth recording rather than what a cuff showed. That makes the direction more trustworthy than the size. A risk ratio of 2.45 for hypotension-related events sounds alarming, but it multiplies a small baseline rate, so the absolute number of extra events is modest; the wide interval of 1.35 to 4.45 reflects how few events there were. Semaglutide's intervals both cross 1.0, which means no effect was shown in either direction rather than that the drug was proven neutral. The dose-dependence, with a higher ratio at higher doses, is the finding that most supports a real drug effect rather than a reporting artefact.
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