Both FDA-approved. One clear winner in the data. A side-by-side comparison using 10,464 real patient posts from Reddit, published clinical trial data, and 768 people who switched between them. Not medical advice — evidence to inform your conversation with your doctor.
Clinical trial results at the highest studied doses. No head-to-head trial exists — these are cross-trial comparisons.
These trials enrolled similar populations but were not head-to-head. SURMOUNT-1 mean BMI was 38.0; STEP 1 mean BMI was 37.9 — the closest baseline comparison of any two GLP-1 trials. Tirzepatide’s dual GIP/GLP-1 mechanism provides additional metabolic activity that semaglutide’s single GLP-1 action doesn’t have. This 6-percentage-point gap is consistent across multiple trial readouts.
Percentage of Reddit posts for each drug mentioning each side effect, with raw post counts shown. Based on 5,380 tirzepatide and 5,084 semaglutide posts.
| Side Effect | Tirzepatide | Semaglutide | Signal |
|---|---|---|---|
| Nausea | 14.3%769 posts | 21.2%1,076 posts1.5× | Sema-Elevated Semaglutide has the highest nausea rate of all three GLP-1 drugs. 1,076 posts — the single largest side effect signal in the dataset. |
| Fatigue | 9.1%488 posts | 9.8%497 posts | Similar rates. Sema fatigue (9.8%) near-perfectly matches the Wegovy FDA label (11%). |
| Diarrhea | 5.2%279 posts | 6.6%335 posts | Sema modestly higher. |
| Constipation | 5.8%311 posts | 6.3%322 posts | Both elevated. Sema slightly higher. |
| Acid Reflux | 2.8%148 posts | 4.5%229 posts1.8× | Sema-Elevated Sema nearly double tirz. Consider PPI prophylaxis when starting semaglutide. |
| Hair Loss | 4.2%228 posts1.7× | 3.1%159 posts | Tirz-Elevated Tirzepatide’s main unique burden. Telogen effluvium from more rapid weight loss. Appears months 3–6. Confirmed by meta-analysis (OR 5.76). |
| Vomiting | 1.8%97 posts | 3.0%150 posts1.6× | Sema-Elevated Both massively underreported vs trials (sema trial: 24.8%, tirz trial: 12.2%). |
| Depression | 1.1%60 posts | 1.9%98 posts2.1× | Sema-Elevated 12.4% of depression posts led to stopping in our dataset. FDA reviewed suicidal ideation concerns in 2024 and found no causal link. Document baseline mood when starting either drug. |
| Gallbladder Issues | 1.3%71 posts | 0.8%42 posts | Tirz-Elevated Tirz modestly higher. 14.4% stop rate in our dataset when it occurs — the highest of any side effect. |
Semaglutide has a worse side effect profile across nearly every GI metric — nausea (1,076 vs 769 posts), vomiting (150 vs 97), acid reflux (229 vs 148), diarrhea (335 vs 279), and depression (98 vs 60). Tirzepatide’s main unique burden is hair loss (228 posts, 1.4× sema) and slightly elevated gallbladder issues (71 posts). This is the simplest comparison of the three: semaglutide hits harder on nearly everything, but has the longer safety track record.
Published trial results compared to what 10,464 Reddit users reported. Arrows show whether Reddit under- or over-counts relative to trials.
| Side Effect | Tirz Trial | Tirz Reddit | Sema Trial | Sema Reddit | Pattern |
|---|---|---|---|---|---|
| Nausea | 31.0% | 14.3%769 | 43.9% | 21.2%1076 | ↓ Undercounted |
| Vomiting | 12.2% | 1.8%97 | 24.8% | 3.0%150 | ↓↓ Heavily under |
| Diarrhea | 23.0% | 5.2%279 | 29.7% | 6.6%335 | ↓ Undercounted |
| Constipation | 11.7–16.8% | 5.8%311 | 24.2% | 6.3%322 | ↓ Undercounted |
| Fatigue | N/A | 9.1%488 | 11% | 9.8%497 | → Sema aligned |
| Hair Loss | OR 5.76 | 4.2%228 | N/A | 3.1%159 | → Consistent |
| Palpitations | Not in SURMOUNT | 2.4%128 | N/A | 1.8%91 | ★ New signal |
Reddit systematically undercounts acute GI symptoms (nausea, vomiting, diarrhea) because people don’t open Reddit mid-episode. But the relative ranking is preserved: semaglutide has higher GI rates in both trials and Reddit data. Semaglutide’s fatigue rate is the single best Reddit-to-trial alignment in the dataset — 9.8% vs the Wegovy label’s 11%. When Reddit and trials measure the same quality-of-life effect, they converge.
Signals invisible to clinical research by design — plus where trials and Reddit agree.
Semaglutide fatigue on Reddit (9.8%) near-perfectly matches the Wegovy FDA label (11%) — the single best Reddit-to-trial alignment in the dataset. Tirzepatide hair loss on Reddit (4.2%) is consistent with the meta-analysis finding (OR 5.76). When the two data sources measure the same quality-of-life effect, they converge — which gives us confidence in the signals Reddit captures that trials don’t.
Of all side effect reports, what percentage were rated mild, moderate, or severe.
Semaglutide has the worst severity profile of all three GLP-1 drugs — 30% of 4,144 reports rated severe, vs 27% for tirzepatide. Semaglutide also has the lowest mild rate (27% vs 32%). This likely reflects semaglutide’s more intense GI burden: nausea and vomiting are inherently more acutely debilitating than tirzepatide’s characteristic side effects like hair loss or constipation.
Positive effects reported beyond weight loss, with raw post counts. Benefits are underreported — people post about problems more than wins.
| Benefit | Tirzepatide | Semaglutide | Signal |
|---|---|---|---|
| Food Noise Eliminated | 18.0%967 posts | 17.3%879 posts | Essentially identical rates. Both drugs are highly effective at eliminating food noise. |
| Energy Increased | 12.3%663 posts2.6× | 5.0%253 posts | Tirz Leads The biggest benefit gap between these two drugs. Multiple posts describe energy gains appearing before significant weight loss. |
| Blood Pressure Normalized | 7.3%393 posts2.5× | 4.9%250 posts | Tirz Leads Tirz leads in both rate and raw count. |
| Inflammation Reduced | 7.1%384 posts2.6× | 2.8%141 posts | Tirz Leads Joint pain and CRP improvements frequently cited. Benefits appear before major weight loss in multiple posts. |
| Mental Clarity | 6.2%331 posts2.5× | 3.1%158 posts | Tirz Leads Tirz leads at 2.5× the rate. |
| Reduced Alcohol Cravings | 3.2%173 posts | 2.9%148 posts | Essentially identical — mechanism-level GLP-1 effect on nucleus accumbens. |
Tirzepatide has a dramatically stronger benefit profile — 2.5× the rate of energy gains (663 vs 253 posts), blood pressure improvement (393 vs 250), inflammation reduction (384 vs 141), and mental clarity (331 vs 158). Food noise elimination and alcohol craving reduction are identical across both drugs. Tirzepatide’s dual GIP/GLP-1 mechanism appears to deliver substantially more anti-inflammatory, cardiovascular, and energy effects than semaglutide’s single GLP-1 action.
The SELECT trial (n=17,604) showed semaglutide reduced major adverse cardiovascular events by 20% in people with existing cardiovascular disease but without diabetes. No other GLP-1 drug has this evidence yet. This is not captured in the Reddit benefit data above, but it’s the single strongest clinical argument for semaglutide — particularly for patients with a history of heart disease. Tirzepatide’s SURPASS-CVOT cardiovascular outcomes trial is ongoing.
768 people in our dataset switched between these two drugs. The flow — and the satisfaction data — tells a clear story.
How people felt after switching — based on posts with outcome data.
Tirzepatide is the most satisfying switch destination in the entire dataset — 36% positive with just 4% negative. Semaglutide as a destination performs poorly: 16% positive, 13% negative. The switching flow is 2:1 sema→tirz, and the satisfaction gap is 9:1. Most tirz→sema switches are insurance-driven, not by choice — which explains the low satisfaction. When people switch for efficacy reasons, they move toward tirzepatide.
Based on the data — not a recommendation. Always discuss with your healthcare provider.
Search all 14,252 posts across retatrutide, tirzepatide, and semaglutide.
22-page analysis — side effects, remedies, benefits, women’s health, clinical trial comparisons, and recommendations by drug.