Tirzepatide vs Orforglipron: Weight Loss, Side Effects
Tirzepatide and orforglipron are both GLP-1 medicines, weekly injection versus daily tablet. In their own trials, average weight loss was 20.9% and 11.1%. Self-pay starts at $299 per month for Tirzepatide and $149 per month for Orforglipron.
Foundayo and Zepbound at a glance
Orforglipron and Tirzepatide side by side
| Tirzepatide | Orforglipron | |
|---|---|---|
| Medicine | tirzepatide |  orforglipron |
| Active ingredient | tirzepatide | orforglipron |
| Manufacturer | Eli Lilly | Eli Lilly |
| How it is taken | Weekly injection | Daily tablet |
| Approved for | Sleep apnea, heart risk, Type 2 diabetes, and weight loss | Weight loss |
| First FDA approval | 2022 | 2026 |
| Average weight loss in trials | 20.9% (SURMOUNT-1, 72 weeks) | 11.1% (ATTAIN-1, 72 weeks) |
| Most common side effect | Nausea 18% vs 4% on placebo | Nausea 35% vs 10% on placebo |
| List price | $1,112.16 per fill | $649 per month |
| Self-pay from | $299 per month | $149 per month |
| Medicare GLP-1 Bridge | $50 per month, eligible Part D | $50 per month, eligible Part D |
| FDA shortage | Resolved December 19, 2024 | Not listed |
Sources: FDA label, FDA label (DailyMed), pricinginfo.lilly.com, TrumpRx.
Weight loss compared
Since no trial has compared the drugs head to head, the numbers come from studies with different groups and durations.
| Trial | Who took part | Length | Group | Average weight loss | Placebo |
|---|---|---|---|---|---|
| SURMOUNT-1 | Adults with obesity or overweight, without diabetes | 72 weeks | Tirzepatide 5 mg weekly | 15% | 3.1% |
| SURMOUNT-1 | Adults with obesity or overweight, without diabetes | 72 weeks | Tirzepatide 10 mg weekly | 19.5% | 3.1% |
| SURMOUNT-1 | Adults with obesity or overweight, without diabetes | 72 weeks | Tirzepatide 15 mg weekly | 20.9% | 3.1% |
| SURMOUNT-2 | Adults with obesity or overweight who also have type 2 diabetes | 72 weeks | Tirzepatide 10 mg weekly | 12.8% | 3.2% |
| SURMOUNT-2 | Adults with obesity or overweight who also have type 2 diabetes | 72 weeks | Tirzepatide 15 mg weekly | 14.7% | 3.2% |
| ATTAIN-1 | Adults with obesity or overweight, without diabetes | 72 weeks | Foundayo 5.5 mg daily | 7.4% | 2.1% |
| ATTAIN-1 | Adults with obesity or overweight, without diabetes | 72 weeks | Foundayo 9 mg daily | 8.3% | 2.1% |
| ATTAIN-1 | Adults with obesity or overweight, without diabetes | 72 weeks | Foundayo 17.2 mg daily | 11.1% | 2.1% |
| ATTAIN-2 | Adults with obesity or overweight who also have type 2 diabetes | 72 weeks | Foundayo 5.5 mg daily | 5.1% | 2.5% |
| ATTAIN-2 | Adults with obesity or overweight who also have type 2 diabetes | 72 weeks | Foundayo 9 mg daily | 7% | 2.5% |
| ATTAIN-2 | Adults with obesity or overweight who also have type 2 diabetes | 72 weeks | Foundayo 17.2 mg daily | 9.6% | 2.5% |
Trial sources: SURMOUNT-1 (FDA label (DailyMed)), SURMOUNT-2 (PubMed), ATTAIN-1 (FDA label (DailyMed)).
Side effects compared
Testing under every label involved its own participants and its own placebo group. This means you should first compare each drug with its own placebo.
| Side effect | Mounjaro | Placebo (Mounjaro trials) | Foundayo | Placebo (Foundayo trials) |
|---|---|---|---|---|
| Nausea | 18% | 4% | 35% | 10% |
| Diarrhea | 17% | 9% | 25% | 11% |
| Decreased Appetite | 11% | 1% | Not listed | Not listed |
| Vomiting | 9% | 2% | 24% | 4% |
| Dyspepsia | 8% | 3% | 16% | 4% |
| Constipation | 7% | 1% | 27% | 9% |
| Abdominal Pain | 6% | 4% | 14% | 7% |
| Headache | Not listed | Not listed | 9% | 7% |
| Abdominal distension | Not listed | Not listed | 9% | 3% |
Price and coverage compared
| Medicine | How you pay | Price |
|---|---|---|
 Mounjaro | List price before insurance | $1,112.16 per fill |
| Mounjaro | Mounjaro Savings Card (insured) | from $25 for up to a 3-month fill |
| Mounjaro | Commercial plan that does not cover it | $499 per month |
 Zepbound | List price before insurance | $499 to $1,086 per fill |
| Zepbound | Zepbound Savings Program (insured) | from $25 for up to a 3-month fill |
| Zepbound | Self-pay: LillyDirect vial or KwikPen 2.5 mg | $299 per month |
| Zepbound | Commercial plan that does not cover it | $299 per month |
| Zepbound | Medicare GLP-1 Bridge (Zepbound KwikPen, eligible Part D) | $50 per month |
| Foundayo | List price before insurance | $649 per month |
| Foundayo | Foundayo Savings Card (insured) | from $25 per month |
| Foundayo | Self-pay: LillyDirect 0.8 mg and 2.5 mg | $149 per month |
| Foundayo | Medicare GLP-1 Bridge (Foundayo, eligible Part D) | $50 per month |
Prices checked November 2026 (9)
pricinginfo.lilly.com 1 2 3, mounjaro.lilly.com, zepbound.lilly.com, Eli Lilly 1 2, CMS, foundayo.lilly.com.
Who should pick which?
- No needles required: Orforglipron is a tablet, while Tirzepatide is given as a weekly injection.
- Type 2 diabetes: Only Tirzepatide has approval for it.
- Tirzepatide is approved as a treatment for sleep apnea.
- Heart attack and stroke risk: Tirzepatide has approval to lower it.
- Tirzepatide is approved for some children under 18.
- Paying cash: Orforglipron starts at a lower price, $149 per month.
Whether to switch is your prescriber's decision, based on your health history, other medicines, and coverage.