Summary
Common Side Effects
Important Context: All side effect data below come from Phase 2 clinical trials of Maritide. These are typical for the GLP-1 receptor agonist class and are generally mild to moderate in severity. Most GI events occurred with the first dose and resolved within days.
Most Common Adverse Events (Phase 2)
| Adverse Event | Maritide Frequency | Severity | Resolution Time |
|---|---|---|---|
| Nausea | Common (% not disclosed) | Predominantly mild | Median: 6 days |
| Vomiting | 22-24% (Phase 1) | Predominantly mild and transient | Median: 1-2 days |
| Constipation | Common (reported) | Mild to moderate | Variable |
| Diarrhea | Common (reported) | Mild to moderate | Self-limiting |
| Retching | Reported | Mild to moderate | Variable |
Discontinuation Due to Adverse Events
Individual Side Effect Details
Nausea
Vomiting
Constipation
Diarrhea
Retching (Dry Heaves)
Timeline
Understanding the Pattern
Maritide's monthly dosing creates a unique side effect timeline. Most GI events occur with the first injection, with subsequent monthly doses better tolerated as your body adapts.
Typical Side Effect Progression
First Injection (Day 1-7): Initial Dose
What to expect: Nausea, vomiting, or constipation most likely to occur. These are typically mild to moderate and transient.
Key finding: Nausea resolves within a median of 6 days; vomiting within 1-2 days.[1]
Management tip: Prepare for the first injection by having bland foods available and clearing your schedule if possible for the first few days.
Weeks 2-4: Between First and Second Dose
What to expect: GI symptoms should have resolved or significantly improved. Maritide's 21-day half-life maintains steady drug levels throughout the month.
Management tip: This is when you'll experience the benefits (appetite suppression, weight loss) without acute GI side effects.
Second Injection (Week 4-5): Dose Escalation
What to expect: If using dose escalation protocol, the second dose may be higher. GI events can recur but are typically milder than the first dose.
Key finding: Dose escalation substantially reduces GI side effects compared to fixed high-dose initiation.[2]
Management tip: Use the same strategies that worked for your first injection. Side effects should be briefer this time.
Month 2-3+: Maintenance Dosing
What to expect: Your body has adapted to Maritide. Monthly injections should cause minimal to no GI side effects.
Key finding: Over 90% of eligible participants chose to continue treatment in Phase 2 extension, indicating high long-term tolerability.[1]
Management tip: If GI side effects persist beyond month 2-3, discuss with your doctor whether a lower maintenance dose might be appropriate.
Monthly Dosing Advantage: With only 12 injections per year (vs. 52 for weekly GLP-1s), you experience 40 fewer "first-dose" GI events annually—potentially improving overall tolerability despite similar side effect types.
Mechanism
How Maritide Works
Maritide is a unique GLP-1 receptor agonist + GIP receptor antagonist. While this dual mechanism is highly effective for weight loss, the GLP-1 activation component explains why gastrointestinal side effects occur—these are a class effect of all GLP-1 therapies.
The Connection Between How It Works and Side Effects
What it does: GLP-1 receptor agonists slow the rate at which food moves from your stomach to your intestines. This helps you feel full longer and reduces appetite.
Side effect connection: Food staying in your stomach longer can cause nausea, bloating, feeling overly full after small meals, and potentially vomiting.
Why it improves: Your digestive system gradually adapts to the slower emptying rate over days to weeks, which is why most nausea resolves within 6 days.
What it does: Activating GLP-1 receptors in the brain's appetite centers reduces hunger signals and increases satiety.
Side effect connection: GLP-1 receptors are also present in the gut's nausea/vomiting centers, which can be overstimulated initially—especially with the first dose or dose increases.
Why it improves: These receptors become less sensitive to stimulation over time (desensitization), reducing nausea and vomiting with subsequent doses.
What it does: GLP-1 affects the coordinated muscle contractions that move food through your digestive system.
Side effect connection: Altered motility can cause either diarrhea (if motility is too fast in intestines) or constipation (if too slow), depending on individual response and which part of the GI tract is most affected.
Why it improves: Your gut's nervous system adjusts to the new signaling pattern, restoring more normal motility over time.
What it does: Maritide's 21-day half-life provides sustained drug exposure throughout the entire month between injections.
Side effect connection: Steady drug levels between doses may prevent the "peaks and valleys" that contribute to GI symptoms with some shorter-acting medications. However, the longer duration means once dosed, you're committed to that dose level for several weeks.
Why it improves: Most GI events are concentrated at the injection day (first dose effect), with minimal side effects between injections thanks to stable drug levels.
Class Effect: These GI side effects are seen with all GLP-1 receptor agonists (injectable and oral) because they share GLP-1 activation. Maritide's safety profile for GI events is consistent with semaglutide (Wegovy, Ozempic), tirzepatide (Zepbound), and other GLP-1 therapies. The GIP antagonism component is unique to Maritide but does not appear to add additional GI side effects.
Dose Escalation Strategy
The most important factor determining Maritide tolerability is dose escalation—starting low and increasing gradually. Phase 3 trials use an optimized 8-week escalation protocol that dramatically reduces side effects:
- Week 0: 21 mg starting dose
- Week 4: Increase to 35 mg
- Week 8: Increase to 70 mg
- Week 12+: Continue at target maintenance dose or escalate further if tolerated
Why Dose Escalation Works
| Dosing Strategy | Discontinuation Rate (GI Events) | Key Finding |
|---|---|---|
| Dose Escalation (Optimized) | <8% | Phase 1: 0% GI discontinuations[2] |
| Non-Escalated (Fixed High Dose) | 12-27% | 2-3x higher discontinuation[1] |
Mechanism: Gradual dose increases allow your body's GLP-1 receptors to adapt slowly, preventing the overstimulation that causes severe nausea and vomiting. Starting at 21 mg instead of jumping to 420 mg reduces the "shock" to your system.
Clinical Impact: The difference between <8% and 27% discontinuation rates is substantial—optimized dose escalation allows 3x more patients to successfully stay on treatment long-term.
Bone Mineral Density: No Safety Signal
In November 2024, Amgen proactively addressed market speculation about potential bone density effects from Maritide's unique mechanism (GIP antagonism):[3]
- "No association between MariTide administration and bone mineral density changes"
- "Phase 1 study results do not suggest any bone safety concern"
- Comprehensive bone safety monitoring included in Phase 3 MARITIME program
Why this matters: Some researchers theorized that GIP receptor antagonism (Maritide's unique feature) might affect bone density because GIP plays a role in bone metabolism. However, Phase 1 data showed no such effect, and Amgen is continuing to monitor bone health closely in Phase 3 trials.
Comparison to other GLP-1 therapies: Bone density concerns have not been a significant issue with approved GLP-1 medications like Wegovy or Zepbound. Maritide appears to follow this same safe profile.
FAQs
Most gastrointestinal side effects with Maritide are concentrated around the injection day and resolve quickly. Nausea typically resolves within a median of 6 days, while vomiting resolves within 1-2 days. Because Maritide is dosed monthly (not weekly), you experience far fewer "first-dose" events compared to weekly GLP-1s—only 12 times per year versus 52.
No. While GI side effects are common with GLP-1 medications, they're not universal. With optimized dose escalation in Phase 1 studies, discontinuation due to GI events was 0%. Starting at a lower dose (21 mg) and escalating gradually over 8 weeks substantially reduces the risk and severity of nausea and other GI symptoms.
Maritide has a similar GI side effect profile to semaglutide (Ozempic/Wegovy) and tirzepatide (Zepbound/Mounjaro)—all primarily cause nausea, vomiting, and constipation. The key difference is dosing frequency: Maritide's monthly injection means you only experience potential first-dose side effects 12 times per year compared to 52 times with weekly options. This may improve overall tolerability for some people.
No safety signal has been identified. In November 2024, Amgen proactively addressed market speculation by stating there is "no association between MariTide administration and bone mineral density changes" based on Phase 1 data. Comprehensive bone safety monitoring continues in Phase 3 trials. This was a theoretical concern due to Maritide's unique GIP antagonism mechanism, but clinical data has not shown any bone-related issues.
Dose escalation dramatically improves tolerability. In Phase 2 trials, non-escalated dosing led to 12-27% discontinuation due to GI events, while dose escalation reduced this to less than 8%. Phase 1 studies with optimized escalation achieved 0% GI-related discontinuations. Starting at 21 mg and gradually increasing to 35 mg, then 70 mg over 8+ weeks allows your body to adapt to the medication.
Maritide combines GLP-1 receptor agonism (like Ozempic/Zepbound) with GIP receptor antagonism—a unique dual approach. The GLP-1 activation causes the typical GI side effects seen with all GLP-1 medications. The GIP antagonism is what sets Maritide apart and may contribute to its efficacy, but importantly, it does not appear to add additional GI side effects beyond what's expected from the GLP-1 component.
Sources
- Amgen. "AMGEN ANNOUNCES ROBUST WEIGHT LOSS WITH MARITIDE IN PEOPLE LIVING WITH OBESITY OR OVERWEIGHT AT 52 WEEKS IN A PHASE 2 STUDY." Amgen Newsroom. November 26, 2024. Link
- Amgen. "RESULTS FROM AMGEN'S PHASE 2 OBESITY STUDY OF MONTHLY MARITIDE PRESENTED AT THE AMERICAN DIABETES ASSOCIATION 85TH SCIENTIFIC SESSIONS." Amgen Newsroom. June 2025. Link
- Amgen. "AMGEN PROVIDES STATEMENT ON MARITIDE PHASE 1 DATA." Amgen Newsroom. November 13, 2024. Link
- FDA. "OZEMPIC (semaglutide) injection - Prescribing Information: Boxed Warning and Contraindications." DailyMed. 2025. Link
- Wilding JPH, Batterham RL, Calanna S, et al. "Once-Weekly Semaglutide in Adults with Overweight or Obesity." N Engl J Med. 2021;384(11):989-1002. doi:10.1056/NEJMoa2032183. Link
Last updated October 6, 2026
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