Tirzepatide Versus Semaglutide on Mood

People choosing between these two drugs often want to know whether one is harder on mood. A study of roughly 80,000 matched pairs followed for two years gives an unusually clean answer: no difference. The composite psychiatric outcome came out at 0.984 in year one and 1.002 in year two.^[1]

The head-to-head

Hazard ratios that land on 0.98 and 1.00 across two years, in a sample that size, are about as close to a genuine null as observational data produces. Whatever separates these two drugs, psychiatric risk over two years does not appear to be it.^[1]

The comparison that did show something

Against earlier-generation GLP-1 drugs rather than against tirzepatide, semaglutide looked different — and consistently so across every psychiatric outcome measured in year one.

The suicidal ideation figure is the one to sit with, given how much public argument this drug class has attracted on exactly that point. It halves, with an interval nowhere near one.

Where this sits with everything else

Three independent bodies of evidence now point the same way. A Swedish national cohort found semaglutide associated with lower risk of worsening mental illness and the class associated with less self-harm, which we covered in worsening mental illness. This study finds lower psychiatric event rates against older drugs in the class. And a randomized trial in major depressive disorder found no increase in suicidal ideation, covered here.

Pointing the other way is a spontaneous-reporting signal from FDA adverse event data, discussed in the FAERS analysis. That is the weakest design of the four, and the most susceptible to amplification by the news coverage this question generated.

Three matched cohorts and a randomized trial on one side. Voluntary reports on the other.

The same caution applies here as everywhere in this class: semaglutide reaching better outcomes than older drugs may reflect who receives the newest and most effective option rather than the molecule. That confound does not touch the tirzepatide comparison, though — both are current, both are prescribed to similar people, and the answer there was no difference.