MariTide vs. Wegovy vs. Zepbound: Monthly vs. Weekly Shots Compared

MariTide, Amgen's once-monthly obesity shot, is still in phase 3 trials as of October 2026 and is not approved anywhere, so you cannot get it outside a clinical trial. Its phase 2 results (up to about 20% weight loss at 52 weeks) look competitive with Zepbound and stronger than Wegovy, but those numbers come from a different trial design and a more favorable way of counting. For most people deciding now, the real choice is between two weekly drugs you can start today and a monthly drug that is likely years away.

The three drugs at a glance

Cross-trial comparison, not head to head. Sources: Amgen, STEP 1, NEJM 2021, Zepbound label, NovoCare, Lilly.

Why MariTide's numbers are not directly comparable

Three differences make the MariTide figure look better than a fair comparison would.

1. The counting method. Amgen reported its phase 2 results using the efficacy estimand, which estimates weight loss as if everyone stayed on treatment, according to the company's November 2024 announcement. The Zepbound and Wegovy figures above count everyone who started, including people who stopped. Efficacy-estimand numbers typically run higher.
2. The timeline. MariTide's results are at 52 weeks; Wegovy's at 68 and Zepbound's at 72. Amgen said it saw no weight-loss plateau at 52 weeks, which suggests the gap could widen with time, but that remains to be shown.
3. The phase. Phase 2 trials are smaller and used to choose doses. Results in larger phase 3 trials can differ from phase 2 headlines. MariTide's phase 3 MARITIME trials will settle the question.

Even so, the phase 2 data are strong. In people with type 2 diabetes, MariTide produced up to about 17% weight loss and lowered HbA1c by up to 2.2 percentage points, per Amgen.

Monthly vs. weekly: what you would actually gain

The main appeal of MariTide is fewer injections: 12 shots a year instead of 52, and fewer still if dosing every 8 or 12 weeks proves to work. It is also built differently from other GLP-1 drugs. Amgen describes it as an antibody-peptide conjugate that activates the GLP-1 receptor and blocks the GIP receptor, and it is being studied as a monthly or less frequent injection, per Amgen.

Interestingly, MariTide blocks GIP while Zepbound activates it. Both approaches have produced substantial weight loss, which shows the science of GIP is still being worked out.

Side effects and tolerability

All three drugs cause mainly gastrointestinal side effects. The differences lie in timing and how often people quit.

• MariTide: Nausea, vomiting, and constipation were most common, mostly mild and short-lived and concentrated around the first dose. Starting at a lower dose and stepping up reduced them. In the dose-escalation groups, about 11% stopped for any side effect, and under 8% for gastrointestinal ones, per Amgen.
• Wegovy: In weight-loss trials, 6.8% of people on 2.4 mg stopped because of side effects, versus 3.2% on placebo, per the Wegovy label.
• Zepbound: Between 4.8% and 6.7% stopped for side effects depending on dose, versus 3.4% on placebo. Nausea affected 25% to 29% of people across doses, per the Zepbound label.

These discontinuation rates come from different trials and are not directly comparable either.

Wegovy vs. Zepbound: the choice you can make today

Among the two approved drugs, Zepbound has produced more weight loss. In SURMOUNT-5, a 72-week head-to-head trial in 751 adults with obesity and no diabetes, tirzepatide at the maximum tolerated dose led to 20.2% average weight loss versus 13.7% with semaglutide, according to the NEJM publication. In Zepbound's label trial, 56.7% of people on 15 mg lost at least 20% of their body weight.

Wegovy has its own advantages. Its label includes a proven reduction in heart attacks and strokes for people with heart disease, a daily pill version, and a higher 7.2 mg dose (Wegovy HD) for people who need more weight loss after tolerating 2.4 mg. NovoCare lists Wegovy HD at $399 per month self-pay, and the standard pens at $349, with a $199 introductory price for the first two starter fills through December 31, 2026.

Zepbound self-pay prices are $299 per month at 2.5 mg, $399 at 5 mg, and $449 at 7.5 mg through 15 mg, for either vials or the KwikPen. Lilly set those vial prices in December 2025, according to BioSpace. Lilly's savings page lists the same tiers for the KwikPen, with two conditions: the $449 KwikPen price requires a refill within 45 days of the last one, and the current self-pay card ends December 31, 2026.

Where MariTide stands in October 2026

Amgen's phase 3 program includes trials in people with and without type 2 diabetes. Public registries show:

• MARITIME-1 extension: Started July 23, 2026, enrolling about 3,200 people who finished 72 weeks in the main obesity trial. Participants on medium or high doses are re-randomized to dosing every 4 or 8 weeks (and, at the high dose, every 12 weeks) or placebo. Its primary completion is estimated for December 2027, per ClinicalTrials.gov.
• MARITIME-2 extension: For people with obesity and type 2 diabetes, it re-randomizes some participants to dosing every 4 weeks or every 8 weeks, per its ClinicalTrials.gov record.
• MARITIME-SWITCH: Tests moving people who lost at least 10% on a weekly GLP-1 over to MariTide, with about 300 participants, per its listing.
• MARITIME-3-J: A 72-week Japanese trial of 272 people that began enrolling in June 2025, per Japan's trial registry.

Phase 3 efficacy results have not been reported yet, so no approval date is in sight. The existence of the switch trial is a useful signal: if MariTide is approved, moving from a weekly drug to it is a scenario Amgen expects and is studying.

Questions to ask before you decide to wait

If a monthly shot sounds appealing, these questions can help you and your prescriber weigh the tradeoff honestly.

• What does waiting cost me? If you have weight-related conditions such as high blood pressure, prediabetes, sleep apnea, or heart disease, months or years without treatment carry real health costs. Wegovy and Zepbound have approved uses for some of these conditions.
• Is injection frequency my real barrier? If weekly shots are the main reason you are hesitating, a daily pill may be another route. Wegovy is available as a tablet, per its label.
• Can I switch later? Likely, if MariTide is approved. MARITIME-SWITCH is enrolling adults with a BMI of 25 or higher who lost at least 10% on a weekly GLP-1 and are on a stable, tolerated dose. People with diabetes are excluded from that trial.
• What will it cost? MariTide's price is unknown. Wegovy and Zepbound both have self-pay programs today, and Lilly cut Zepbound's self-pay prices as recently as December 2025.

Sources

1. Amgen: MariTide phase 2 52-week results (November 2024)
2. Amgen: Inside the phase 3 MARITIME program (June 2025)
3. ClinicalTrials.gov: MARITIME-1-EXTENSION (NCT07684235)
4. ClinicalTrials.gov: MARITIME-2-EXTENSION (NCT07684144)
5. MARITIME-SWITCH (NCT07575399) trial record
6. Japan Registry of Clinical Trials: MARITIME-3-J
7. Zepbound (tirzepatide) prescribing information
8. Wegovy (semaglutide) prescribing information
9. Wilding JPH, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). NEJM, 2021
10. Aronne LJ, et al. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity (SURMOUNT-5). NEJM, 2025
11. NovoCare: Wegovy self-pay pricing
12. BioSpace: Lilly cuts Zepbound prices again in its direct-to-consumer program
13. Eli Lilly: Zepbound coverage and savings

Medical disclaimer: This article is general information, not medical advice, and does not replace a licensed clinician who knows your history. Approvals, labels, coverage and prices change; check the linked sources and talk with your prescriber or pharmacist before making decisions about any medication.