MariTide: The once-monthly weight loss medication in trials

Medications like Wegovy® and Zepbound® have become well-known in the weight loss space, but the field is moving faster than ever. Recent years have brought a wave of new options—from the Wegovy® pill and higher-dose Wegovy® 7.2 mg to the newly approved Foundayo®—and researchers are continuing to develop treatments that work through entirely different pathways. 

Two in particular have drawn significant attention: retatrutide, a triple-hormone agonist from Eli Lilly still in phase 3 trials, and CagriSema, a combination therapy from Novo Nordisk that is currently under FDA review. One newer medication in testing that is also getting a lot of attention is MariTide. Still in development, MariTide is an investigational treatment being studied for weight loss and related conditions, designed to be once-a-month instead of daily or weekly like today’s medications.

Aside from the frequency, MariTide also stands out for how it works. MariTide activates the GLP-1 receptor—similar to existing treatments—but also blocks (rather than activates) the GIP hormone pathway. Like the other GLP-1 medications, it’s designed to lower appetite, slow digestion, and regulate blood sugar. Early research has shown promising weight loss outcomes over the course of about a year.

MariTide is still in clinical trials, so it’s not yet available as a prescription option. It’s currently in a phase 3 trial for clinical development, which began in early 2025 and is projected to be completed in 2027. Researchers are continuing to study how effective and safe it is for different groups of people, and timelines for approval can change. 

While the early data is encouraging that this could be an option in the future, there’s still more to learn before it becomes widely available. We’ll break down everything you need to know below.

What is MariTide? 

MariTide (also known by its scientific name, maridebart cafraglutide) is a once-monthly injectable medication currently being studied for weight loss and other metabolic conditions, like type 2 diabetes.

This new medication is being developed by Amgen, a biotechnology company that’s newer to the weight-loss medication space compared to industry leaders like Novo Nordisk and Eli Lilly. Amgen has a long history in developing biologic therapies for complex diseases, and MariTide represents its entry into the rapidly evolving field of weight loss medications.

MariTide is designed to work on two hormone pathways that influence appetite and blood sugar:

• Activates GLP-1 receptors – Like medications such as Wegovy® and Zepbound®, MariTide activates GLP-1 receptors—this is the pathway that helps reduce appetite, slows down how quickly food leaves your stomach, and supports better blood sugar control.
• Blocks GIP receptors – Where things start to differ is with GIP. Unlike tirzepatide (Zepbound®), which activates GIP receptors, MariTide blocks them. By blocking GIP signaling, MariTide may reduce some of the body’s natural tendency to store fat and could shift how energy is used and stored.
• Stays in your system longer – MariTide is built as a peptide-antibody conjugate, a type of larger, long-acting molecule that breaks down more slowly than typical GLP-1 medications. Its half-life is approximately 21 days—about three times longer than the longest-acting weekly GLP-1 medications currently on the market—which is why it’s being studied as a once-monthly injection rather than something you have to take every week.
  • The phase 2 trial also tested an every-other-month dosing arm, and researchers are continuing to evaluate whether less frequent dosing could be an option. The exact dosing plan, including how treatment would start and whether doses would increase gradually, hasn’t been finalized yet.

By targeting these two pathways in different ways, MariTide takes a distinct approach compared to medications that focus on just one mechanism—or even those that activate both GLP-1 and GIP, like Zepbound®. Preclinical studies have suggested that simultaneously activating GLP-1 and blocking GIP may have a stronger effect on weight loss than targeting either pathway alone. And because of its extended half-life, it requires far fewer injections than weekly alternatives, which could make it a more manageable option for many people.

How effective is MariTide, and what is it being studied to treat?

Early research on MariTide has been promising. In a phase 2 clinical trial published in the New England Journal of Medicine, participants taking MariTide lost an average of 12% to 16% of their body weight over 52 weeks, and weight loss hadn’t plateaued by the end of the study, suggesting results could continue to build with longer treatment.

Beyond weight loss, participants also saw improvements in blood sugar levels, which points to potential benefits for people with type 2 diabetes as well as obesity.

As with any medication still in development, important questions remain. Larger phase 3 trials are underway to evaluate long-term safety, side effects, and the most effective dosing approach. MariTide will still need to complete the full regulatory review process before it becomes widely available.

When could MariTide be approved?

MariTide is currently in phase 3 clinical trials—the final stage of testing before Amgen can apply for FDA approval. Phase 3 launched in 2026 under Amgen’s MARITIME program, following phase 2 results published in the New England Journal of Medicine, which showed participants losing an average of 12% to 16% of their body weight over 52 weeks. Phase 3 is expected to run through January 2027. If results are successful, Amgen can submit MariTide for FDA review—a process that can take several months to over a year, putting a potential approval sometime in the late 2020s.

How is MariTide taken only once a month? 

MariTide doesn’t have finalized dosing instructions yet, since it’s still in clinical development. But ongoing research gives a good sense of how it may be used if it’s approved.

In clinical trials, MariTide is being studied as a once-monthly injection given under the skin. That’s possible because MariTide uses an antibody structure that allows it to stay in the body for 3 to 3.5 months, roughly three times longer than current weekly GLP-1 medications.

Researchers have tested several dose levels across trials. In phase 2, doses ranged from 140 mg to 420 mg monthly. The phase 3 MARITIME program is testing lower doses—starting at 21 mg and increasing to 35 mg, then 70 mg over eight weeks—to see whether a more gradual approach improves tolerability.

Some research is also exploring whether dosing could eventually be spaced out to once every three months, though that’s still being evaluated.

Because MariTide isn’t yet approved, final dosing details haven’t been established. If it does become available, your healthcare provider would determine the right plan based on your individual needs.

MariTide: How much weight loss is possible?

So far, the most detailed data comes from a phase 2 clinical trial. In that study, adults with an average BMI of 37.9 and a second group of adults with an average BMI of 36.5 and type 2 diabetes were given MariTide over a 52-week period. Here is what the results showed:

Depending on the dose, participants lost about 12% to 16% of their starting body weight on average. For someone weighing 200 pounds, that could translate to roughly 24 to 32 pounds. People who also had type 2 diabetes still saw meaningful results, though slightly lower on average, in the range of about 8% to 12% weight loss.

Dosing played a role in outcomes, too. In the trial, participants received monthly injections at different dose levels—140 mg, 280 mg, and 420 mg—which helped researchers understand how effectiveness and tolerability might change at higher doses. 

Researchers also looked at whether dose escalation (gradually increasing dose over time) impacted weight loss results, and found that the greatest weight loss of 16.2% occurred when doses were gradually increased every 12 weeks up to 420 mg. As with most medications, higher doses tended to be associated with greater weight loss, but also required careful monitoring for side effects.

When you compare these results to existing options like Zepbound® and Wegovy®, MariTide looks competitive—but it’s still early. At 12% to 16% average weight loss over 52 weeks, it’s in a similar range to Wegovy® (14–15%) and somewhat behind Zepbound® (20–21%). That said, these aren’t direct head-to-head comparisons, so it’s not possible to say definitively that one is better than another yet.

What stands out most is that MariTide may offer similar weight loss potential with a different dosing schedule—monthly instead of weekly—which could be a meaningful advantage for some people. 

MariTide: Side effects and safety

Like any medication, MariTide comes with potential side effects, and understanding them ahead of time can help you feel more prepared. Many of these side effects happen because of how the medication works in your body—especially its effects on hormones that control appetite, digestion, and blood sugar.

MariTide activates GLP-1 receptors and blocks GIP receptors, which changes how quickly your stomach empties, how full you feel, and how your body processes nutrients. Because digestion slows down, food stays in your stomach longer—which can lead to symptoms like nausea, vomiting, or a feeling of fullness. At the same time, shifts in hormone signaling can affect the gut and brain, which is why some people also experience things like diarrhea, constipation, or fatigue as their body adjusts.

The good news is that these side effects are often most noticeable early on and may improve over time, especially when dosing is increased gradually. Researchers are also studying ways to reduce side effects—like starting at lower doses or spacing out injections—to make the medication easier to tolerate.

Most common side effects

The most frequently reported side effects with MariTide are digestive-related, particularly nausea and vomiting, which is something we’ve also seen with other GLP-1–based medications. Here’s what the phase 2 study showed:

Dose	Nausea	Vomiting
140 mg every 4 weeks	8%	12%
280 mg every 4 weeks	9%	10%
420 mg every 4 weeks	14%	15%
420 mg every 8 weeks	16%	24%
420 mg every 4 weeks with 4-week dose escalation*	6%	6%
420 mg every 4 weeks with 12-week dose escalation**	2%	2%

*Participants started at a lower dose and had their dose increased every 4 weeks until 420 mg was reached.
**Participants started at a lower dose and had their dose increased every 12 weeks until 420 mg was reached.

In addition to nausea and vomiting, other gastrointestinal side effects that were seen less frequently (usually less than 5%) included:

• Retching
• Diarrhea
• Constipation
• Gastroesophageal reflux disease (GERD)
  

Other reported issues

Beyond digestive symptoms, some people in trials have reported:

• Headache
• Fatigue or low energy
• Injection-site reactions (like redness, swelling, or mild irritation where the shot is given)
• Malaise (general feeling of discomfort or being unwell)

Severe side effect indications

While less common, there are some more serious risks that are important to be aware of.

These may include:

• Severe or persistent gastrointestinal symptoms that don’t improve
• Acute kidney issues
• Gallbladder issues, such as gallstones
• Heart rate increase

These more serious effects, while uncommon, were reported by at least one participant in the phase 2 study, but more research will be needed to determine whether additional serious risks are possible.

MariTide: Clinical trials and FDA status

MariTide is currently in Phase 3 clinical development for weight loss—the final stage of testing before a medication can be submitted for FDA approval.

Here’s how it has progressed:

Phase 1 (2020-2022)

The earliest studies focused on safety, testing MariTide in a small group of participants. Researchers looked at how the body processes the medication, how long it stays active, and whether people could tolerate it. These findings helped confirm that a long-acting, less frequent dosing schedule could be possible.

Phase 2 (completed June 2025)

Next, MariTide was studied in a larger group of people with obesity, including some with type 2 diabetes. This phase focused on how effective the medication is for weight loss while continuing to monitor safety.

After 52 weeks, participants lost an average of 12% to 16% of their body weight, depending on the dose. In those with type 2 diabetes, average weight loss ranged from about 8% to 12%, along with improvements in blood sugar levels. The most common side effects were gastrointestinal (like nausea and vomiting), which were generally manageable and less frequent with gradual dose increases.

Phase 3 (current)

MariTide is now in Phase 3, the largest and most important stage of testing. These studies involve thousands of participants across multiple countries and are designed to confirm long-term safety and effectiveness.

Amgen, the company developing MariTide, is running a global set of trials known as the MARITIME studies. These trials are comparing MariTide to a placebo and evaluating how well it works across different populations.

Based on current timelines, the main Phase 3 trials are expected to wrap up around January 2027, though early updates may be shared sooner through medical conferences or research releases.

When could MariTide be approved?

If phase 3 results are successful, Amgen could submit MariTide to the FDA shortly after. The review process typically takes 6 to 12 months, which puts a realistic approval window sometime in the late 2020s, with wider availability likely coming after that.

FAQs: Other questions about MariTide

Here are answers to some of the most common concerns about MariTide, covering everything from availability timelines to how it might compare with current options.

When will MariTide be available?

MariTide is currently in clinical trials, with no official approval date announced yet. The timeline depends on study results and FDA review processes, which can take several years. Factors like safety data and manufacturing requirements also influence when new medications become available. If you’re interested in medical weight loss support now, see if you qualify for Noom Med. If so, you’ll be connected with a clinician who can go through your options and prescribe a medication if needed. 

Is MariTide more effective than Zepbound or Wegovy?

Early trial data suggest MariTide may help people lose an average of 12% to 16% of their body weight over one year. For context, Wegovy® averages 14–15% and Zepbound® averages 20–21%. That puts MariTide in a competitive range—though direct comparisons are difficult since these studies involved different populations, timeframes, and methods. It’s also worth noting that MariTide has only completed phase 2 trials, so the full picture is still developing.

What long-term safety data do we have?

Current MariTide studies have followed participants for about one year, showing side effects similar to other GLP-1 medications, like nausea, vomiting, and other digestive issues. In addition to gastrointestinal side effects, other symptoms like headache, fatigue, tiredness, and injection site reactions were also reported. 

More serious side effects were uncommon but included severe or persistent gastrointestinal symptoms, acute kidney issues, gallbladder issues, and an increase in heart rate. Longer-term safety data will come as trials continue. 

What could MariTide cost?

As of now, MariTide is still known by its scientific name, maridebart cafraglutide, rather than a commercial brand name. This is typical during the development phase. If the medication is approved, it would likely be launched under a branded name at that point, along with more information about pricing, insurance coverage, and access.

Because MariTide hasn’t been approved by the FDA yet, there’s no official price available, and Amgen hasn’t released any details about what it might cost if it reaches the market.

Could MariTide be used for conditions beyond weight loss and diabetes?

Research suggests GLP-1-type medications may help with heart health, sleep apnea, and other metabolic conditions. While MariTide trials have focused mainly on weight loss and diabetes management, broader applications are being studied. 

Amgen, MariTide’s manufacturer, is currently exploring additional phase 3 studies that would look at applications for cardiovascular disease, heart failure, kidney disease, and obstructive sleep apnea. Future research will help us understand the full range of potential benefits.

The bottom line: MariTide could be a once-monthly option in the late 2020s

The bottom line is that MariTide is part of a much bigger shift happening in weight loss treatment. It’s not just about newer versions of the same medications—it’s about entirely different approaches to how appetite, metabolism, and fat storage are regulated. A once-monthly option could make treatment feel more manageable for some people, and the early results suggest it may be competitive with what’s already available. But it’s still in development, and the details that matter most—long-term safety, side effects, and how it compares head-to-head—are still being worked out.

For now, MariTide is one to watch, not one to wait for. There are already effective, well-studied options available today, and the best approach is the one you can access, tolerate, and stick with over time. As new medications like MariTide move closer to approval, they’ll likely expand the range of choices—but they won’t replace the fundamentals of what drives results: consistency, support, and a plan that fits your life.

If you’re thinking about medication as part of your weight loss journey, see if you qualify for  Noom Med. If so, you’ll be connected with a clinician who can find the right medication for you and prescribe it if needed. Plus, you’ll get access to medical guidance and behavior-change coaching, helping you build healthier habits that help weight loss stick.