Retatrutide and CagriSema keep appearing in headlines. Both are investigational medicines. That means they are still being tested in clinical trials, and neither is something TOM offers. This post is education only. It explains what the published trials report so you can read the news with context. It sits alongside our medications overview and our post on semaglutide versus tirzepatide.
Information on these drugs changes as trials finish and regulators act. This post reflects what was published as of October 2026. Check the FDA's drug approvals pages for the current status.
What "investigational" means
An investigational medicine is one that has not been approved by the FDA for general use. Researchers test it in stages. Early trials look at safety and dose. Later trials compare the drug with a placebo or another treatment in larger groups. Only after the FDA reviews the full results can a drug be approved.
Until then, a published result is a signal, not a guarantee. It can look strong and still change as larger trials report.
Retatrutide
Retatrutide is being developed by Eli Lilly. It acts on three hormone receptors: GIP, GLP-1, and glucagon. Semaglutide acts on GLP-1. Tirzepatide acts on GIP and GLP-1. That extra glucagon action is what makes retatrutide different on paper.
In a phase 2 trial published in the New England Journal of Medicine, 338 adults with obesity or overweight received retatrutide or placebo for 48 weeks. At the highest dose, the average weight change was about a 24% reduction, compared with about 2% with placebo. Gastrointestinal side effects were common, were related to dose, and were mostly mild to moderate. Heart rate rose with dose, peaked at 24 weeks, and then declined. The trial was funded by Eli Lilly (Jastreboff et al., NEJM, 2023).
That is a phase 2 result. It is a small group studied for under a year. Larger phase 3 trials are underway or have finished, and ClinicalTrials.gov lists the studies and their status (ClinicalTrials.gov: NCT05929066).
CagriSema
CagriSema is being developed by Novo Nordisk. It combines two medicines in one: semaglutide, a GLP-1 medicine, and cagrilintide, which acts on amylin receptors. Amylin is a hormone released with insulin that helps signal fullness.
In the REDEFINE 1 trial, 3,417 adults with obesity or overweight were randomly assigned to cagrilintide-semaglutide or placebo for 68 weeks, alongside lifestyle support. People on the combination lost about 20% of body weight on average, compared with about 3% on placebo. Gastrointestinal side effects were more common with the combination, about 80% versus 40% with placebo, and were mostly mild to moderate. The trial was funded by Novo Nordisk (Garvey et al., NEJM, 2025).
ClinicalTrials.gov lists the trial design and its record (ClinicalTrials.gov: NCT05567796).
How to read these numbers
Three cautions apply to any early-stage headline.
- Averages hide a range. Some people lose more and some lose less.
- Trial conditions are not daily life. Participants get structured follow-up and lifestyle support.
- Company funding does not make results wrong, but it is worth knowing. Both trials above were funded by the companies developing the drugs, and the authors disclose this.
Compare these figures with the medicines that are available now. In the STEP 1 trial of semaglutide, the average weight change was about 15% over 68 weeks (Wilding et al., NEJM, 2021). Trials differ in design, so putting numbers side by side is not a fair race. Only a head-to-head trial can compare two drugs directly.
What this means for you today
You cannot start retatrutide or CagriSema through TOM or through a regular pharmacy. Do not buy products sold online as "retatrutide" or under similar names. A drug that has not been approved can be mislabeled, contaminated, or the wrong strength, and no one has vetted its safety. Our post on compounded medications explains why sourcing matters.
What you can do is learn how approved options work and talk with a clinician about which fits your health. Our pages on semaglutide and tirzepatide describe the medicines Dr. Le can consider for you.
Why waiting is not always the answer
It is tempting to wait for the next big drug. But obesity and its related conditions are health matters now, not later. Starting an approved treatment today does not close any doors. Future drugs, if approved, would be discussed with your clinician at that time, using the evidence available then.
Talk with your care team
If you read about a new medicine and want to understand it, ask. Tell Dr. Le what you saw and what you hoped it would do for you. She can explain how it compares with approved options. You can message the care team any time, and replies usually come in less than 12 hours.
Frequently asked questions
Is retatrutide approved?
It is investigational. Check the FDA's drug approvals pages for the current status.
Does TOM offer retatrutide or CagriSema?
No. Both are investigational, and we do not offer them.
Are trial results the same as real-world results?
Not always. Trials are controlled, and averages vary from person to person.
Why are people buying them online?
Interest is high. Unapproved products carry real risks, so we advise against it.
Start with a free first visit
We serve patients in Texas and Utah. Your first visit with Dr. Le is free. Start here. This article is educational and does not replace medical advice.