Imcivree (Setmelanotide) Explained: Who It's For and How It Works
Imcivree (setmelanotide) is an MC4 receptor agonist for rare obesity caused by hypothalamic injury or specific genetic conditions — not for ordinary obesity. On March 19, 2026, the FDA expanded approval to acquired hypothalamic obesity, making it the first approved therapy for that condition.
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Imcivree is the brand name for setmelanotide, a once-daily injection made by Rhythm Pharmaceuticals that targets a brain pathway called the melanocortin 4 receptor (MC4R) pathway [1][2]. It is approved in the United States for three narrow groups: people age 4 and older with acquired hypothalamic obesity, and people age 2 and older with Bardet-Biedl syndrome or with POMC, PCSK1, or LEPR deficiency confirmed by genetic testing [1]. Its initial U.S. approval was in 2020 [1], and on March 19, 2026, the FDA expanded the label to include acquired hypothalamic obesity, making it the first and only FDA-approved therapy for that condition [2][4].
It is not an alternative or upgrade to Ozempic, Wegovy, or Zepbound. Imcivree works on the MC4R pathway in the hypothalamus rather than on incretin receptors [1][2], and the label explicitly states it is not indicated for general (polygenic) obesity, because it would not be expected to work [1][2].
What is Imcivree and who makes it?
Imcivree is setmelanotide injection, given under the skin (subcutaneously). It comes as a 10 mg/mL solution in a 1 mL multiple-dose vial [1]. The FDA label describes it as a melanocortin 4 (MC4) receptor agonist indicated to reduce excess body weight and maintain that reduction long term [1].
The maker is Rhythm Pharmaceuticals, a commercial-stage biopharmaceutical company headquartered in Boston, Massachusetts, that focuses on rare neuroendocrine diseases [2]. Rhythm describes setmelanotide as an MC4R agonist designed to treat hyperphagia (constant, hard-to-control hunger) and severe obesity [2].
How does the MC4R pathway cause hunger and weight gain?
The MC4R pathway in the brain controls energy expenditure, hunger, and weight regulation [2]. When this pathway is impaired, people experience accelerated and sustained weight gain, often with hyperphagia and/or decreased energy expenditure [2].
In acquired hypothalamic obesity, injury to the hypothalamus can decrease production of alpha-melanocyte-stimulating hormone (α-MSH), which impairs MC4R pathway signaling [2]. In the genetic forms covered by the label, the problem sits in the leptin-melanocortin pathway, while acquired hypothalamic obesity arises from structural damage to the hypothalamic nuclei [4]. In Bardet-Biedl syndrome and Alström syndrome, impaired cilial signaling in the MC4R pathway may contribute to obesity [6].
Hyperphagia means constant, hard-to-control hunger — not feeling full or satisfied after meals [3][4]. The Imcivree patient materials describe MC4R pathway impairment as a root cause of weight gain and hunger in acquired hypothalamic obesity, BBS, and POMC, PCSK1, or LEPR deficiency [3].
Who does the FDA label cover — and who does it exclude?
The label covers three specific populations [1]:
| Indication | Age | How it’s diagnosed |
|---|---|---|
| Acquired hypothalamic obesity (HO) | 4 years and older | Clinical diagnosis [1] |
| Bardet-Biedl syndrome (BBS) | 2 years and older | Clinical diagnosis; genetic confirmation considered in patients under 6 [1] |
| POMC, PCSK1, or LEPR deficiency | 2 years and older | Genetic testing showing variants interpreted as pathogenic, likely pathogenic, or of uncertain significance (VUS) [1] |
The label carries two explicit limitations of use. Imcivree is not indicated when POMC, PCSK1, or LEPR variants are classified as benign or likely benign, and it is not indicated for other types of obesity — including obesity associated with other genetic syndromes and general (polygenic) obesity — because it would not be expected to be effective [1][2].
A few other points from the label and patient materials: no FDA-approved test exists for detecting POMC, PCSK1, or LEPR gene variants [1], and it is not known whether Imcivree is safe and effective in children under 2 years of age [3]. In the European Union and the United Kingdom, authorization covers genetically confirmed BBS or biallelic POMC (including PCSK1) or LEPR deficiency in adults and children 2 and older [2].
What is acquired hypothalamic obesity, and what changed in March 2026?
On March 19, 2026, the FDA approved an expanded Imcivree indication for acquired hypothalamic obesity in adults and pediatric patients age 4 and older, making it the first and only FDA-approved therapy for the condition [2][4]. The label’s Indications and Usage section and Warnings 5.5 and 5.6 carry a 03/2026 revision date [1]. Rhythm stated the drug would be available to U.S. patients immediately at approval [2].
Acquired hypothalamic obesity is rare, marked by accelerated and sustained weight gain caused by injury to the hypothalamus or hypothalamic dysfunction [2]. It most often follows the growth or treatment of craniopharyngioma, astrocytoma, or other hypothalamic-pituitary tumors, including surgery and radiation. Other causes include traumatic brain injury, stroke, and inflammation [2][4]. It can begin as early as six months after the hypothalamic injury [2].
Based on analysis of the literature, tumor registries, and claims data, Rhythm estimates about 10,000 people in the U.S. live with acquired hypothalamic obesity [2]. Before this approval, lifestyle interventions had largely failed to produce meaningful, sustained weight loss in these patients, and researchers studying the condition — including work on insulin modulators, stimulants, incretin-based therapies such as GLP-1 receptor agonists, and MC4R agonists — concluded that acquired HO is “no longer untreatable” [4].
What did the TRANSCEND trial show in acquired hypothalamic obesity?
The approval was supported by the global Phase 3 TRANSCEND trial (NCT05774756), which is ongoing and enrolled 142 patients with acquired HO over 52 weeks: 94 on setmelanotide and 48 on placebo [2][4]. Topline results from a prespecified 120-patient cohort were announced in April 2025, and the extended 142-patient data were read out on March 1, 2026 [4].
The study met its primary endpoint. Rhythm’s release reported a -18.4% placebo-adjusted reduction in BMI, with mean BMI change of -15.8% for setmelanotide versus +2.6% for placebo at 52 weeks (p<0.0001) [2]. AJMC’s reporting of the same dataset gives slightly different figures: a -18.8% placebo-adjusted difference, with -16.4% versus +2.4% (P<.0001) [4]. The two reports disagree on the exact numbers.
Hunger also improved. Among patients age 12 and older (n=98), the weekly average “most hunger” score fell 2.5 points on setmelanotide versus 1.3 points on placebo (P=.0015) [4]. The most common adverse events in TRANSCEND, each affecting more than 20% of participants, were skin hyperpigmentation, nausea, vomiting, and headache; Rhythm described the drug as generally well tolerated in the trial [2].
These figures come from Rhythm’s press release and AJMC’s news reporting, not from the FDA label’s Clinical Studies section, and they reflect 52 weeks of data [2][4].
What did the trials show in Bardet-Biedl syndrome?
The BBS evidence comes from a multicenter, randomized, double-blind, placebo-controlled 14-week Phase 3 trial followed by a 52-week open-label period, run at 12 sites in the USA, Canada, UK, France, and Spain (NCT03746522) [6]. Between December 10, 2018, and November 25, 2019, 38 patients age 6 and older were enrolled and split evenly — 19 on setmelanotide (dosed up to 3.0 mg subcutaneously once daily) and 19 on placebo, with 16 BBS and 3 Alström syndrome patients in each group [6].
The primary endpoint was the share of patients age 12 and older with Bardet-Biedl syndrome who reached at least a 10% bodyweight reduction after 52 weeks of treatment. That figure was 32.3% (95% CI 16.7 to 51.4; p=0.0006) [6]. The most common treatment-emergent adverse events were skin hyperpigmentation in 23 of 38 patients (61%) and injection site erythema in 18 (48%). Two patients had four serious adverse events — blindness, an anaphylactic reaction, and suicidal ideation — none considered related to setmelanotide [6].
The results were inconclusive in the Alström syndrome patients, and Alström is not part of the approved indication [6]. The trial was funded by Rhythm Pharmaceuticals [6].
What did the trials show in POMC and LEPR deficiency?
The POMC and LEPR evidence comes from two single-arm, open-label, multicenter Phase 3 trials at ten hospitals across Canada, the USA, Belgium, France, Germany, the Netherlands, and the UK (NCT02896192 and NCT03287960) [7]. Between February 14, 2017, and September 7, 2018, 10 participants enrolled in the POMC trial and 11 in the LEPR trial, all age 6 and older [7]. The design was 12 weeks of open-label treatment, then an 8-week placebo-controlled withdrawal sequence for responders, then 32 more weeks of open-label treatment [7].
At approximately one year, 8 of 10 participants (80%) in the POMC trial and 5 of 11 (45%) in the LEPR trial achieved at least 10% weight loss [7]. Mean change in the “most hunger” score was -27.1% in the POMC trial (n=7; 90% CI -40.6 to -15.0; p=0.0005) and -43.7% in the LEPR trial (n=7; -54.8 to -29.1; p<0.0001) [7].
Adverse events included injection site reaction and hyperpigmentation in all 10 POMC participants, nausea in 5, and vomiting in 3; in the LEPR trial, injection site reaction occurred in all 11, skin disorders in 5, and nausea in 4. No serious treatment-related adverse events occurred in either trial [7].
The evidence has real limits: 21 patients total, no placebo control arm, and an open-label design [7]. These are small rare-disease trials, not large randomized obesity trials.
How is Imcivree different from Ozempic, Wegovy, and Zepbound?
The core difference is the target. Imcivree is an MC4R agonist that acts on a hypothalamic pathway; it does not act on incretin receptors [1][2]. The label states plainly that Imcivree is not indicated for general (polygenic) obesity [1].
The published material reviewed here does not characterize the mechanisms or drug class of Ozempic, Wegovy, or Zepbound, and it does not report any head-to-head trial between Imcivree and any of them. What the sources do state is that research in acquired hypothalamic obesity has explored several mechanisms, including insulin modulators, stimulants, incretin-based therapies such as GLP-1 receptor agonists, and MC4R agonists [4]. That does not mean incretin drugs are ineffective in hypothalamic obesity — the published research only notes they are among the mechanisms being studied.
Imcivree is injected under the skin once daily, drawn from a vial [1]. Its distinctive side effects also differ from the GI-dominant effects of incretin drugs: skin hyperpigmentation, new or darkened nevi (moles), and spontaneous penile erection are called out on the Imcivree label [1].
What are the warnings and common side effects?
Imcivree is contraindicated in anyone with prior serious hypersensitivity to setmelanotide or its excipients, and serious hypersensitivity reactions including anaphylaxis have been reported [1].
The label’s warnings and precautions include [1]:
- Disturbance in sexual arousal: spontaneous penile erections in males and sexual adverse reactions in females. An erection lasting longer than 4 hours requires emergency medical attention [1][3].
- Depression and suicidal ideation: monitor for new or worsening symptoms; consider discontinuing if suicidal thoughts or behaviors occur, or if depression is clinically significant or persistent [1].
- Skin changes: generalized hyperpigmentation, darkening of existing nevi, and new melanocytic nevi. A full body skin exam is recommended before starting and periodically during treatment [1]. Patient materials state the pigment changes go away after stopping the drug [3].
- Acute adrenal insufficiency in acquired HO: the label says to monitor patients for signs of acute adrenal insufficiency [1]. Patient materials add that patients who have both acquired HO and adrenal insufficiency should have their adrenal function evaluated before starting [3].
- Sodium imbalance in acquired HO with central diabetes insipidus: monitor for hyponatremia and hypernatremia [1].
The most common adverse reactions (incidence of at least 20% in at least one indication) were skin hyperpigmentation, injection site reactions, nausea, headache, diarrhea, abdominal pain, vomiting, depression, and spontaneous penile erection [1].
On pregnancy and lactation: patient materials state that losing weight while pregnant may harm the fetus and that a provider may stop treatment if pregnancy occurs [3]. The label states Imcivree is not recommended when breastfeeding [1], and patient materials likewise say not to breastfeed during treatment [3]. Suspected adverse reactions can be reported to Rhythm at 1-833-789-6337 or the FDA at 1-800-FDA-1088 [1].
How is Imcivree dosed?
The following is label background only — dosing decisions belong to a prescriber. Imcivree is injected subcutaneously once daily, with starting doses that vary by indication and age [1]:
| Group | Starting dosage (once daily for 2 weeks) |
|---|---|
| Acquired HO, age 4 and older | 0.5 mg (0.05 mL) [1] |
| BBS or POMC/PCSK1/LEPR deficiency, age 12 and older | 2 mg (0.2 mL) [1] |
| BBS or POMC/PCSK1/LEPR deficiency, age 6 to under 12 | 1 mg (0.1 mL) [1] |
| BBS or POMC/PCSK1/LEPR deficiency, age 2 to under 6 | 0.5 mg (0.05 mL) [1] |
For adults and pediatric patients age 6 and older across all indications, the maintenance dosage is 3 mg (0.3 mL) once daily [1]. For acquired HO patients age 6 and older, the label’s titration schedule is 0.5 mg in weeks 1–2, 1 mg in weeks 3–4, 2 mg in weeks 5–6, and 3 mg from week 7 onward [1]. If the starting dosage is not tolerated, the label says to discontinue the product, and patients should be monitored for GI adverse reactions during initiation and titration [1]. Maintenance dosing for acquired HO ages 4 to under 6, and for BBS/POMC/PCSK1/LEPR ages 2 to under 6, is determined by body weight, and separate recommendations exist for renal impairment [1]. Detailed Instructions for Use come with the product for preparation, injection, and disposal of syringes and needles [3].
What does Imcivree cost, and how do people get it?
No list price for Imcivree could be verified for this page. Vial price figures circulate only through third-party price guides, and no dollar figure from the manufacturer or the FDA label could be confirmed. Anyone considering the drug should ask the manufacturer and their insurer about cost and coverage.
Rhythm runs a support program called Rhythm InTune, which provides personalized, ongoing educational support for people with acquired HO, BBS, or POMC, PCSK1, or LEPR deficiency [2][3]. It includes education for patients and their health care providers, insurance navigation assistance at treatment initiation, injection support, and guidance on what to expect during treatment [2]. Patient Education Managers provide one-on-one support; they are Rhythm employees and do not provide medical care or advice [3]. The program can be reached at patientsupport@rhythmtx.com [2].
For POMC, PCSK1, or LEPR deficiency, a provider must order a genetic test to confirm the diagnosis before treatment starts [3].
What else is in the pipeline?
Rhythm is advancing two investigational MC4R agonists, bivamelagon and RM-718; neither is FDA approved [2][4]. The company is also developing setmelanotide in other rare diseases and preclinical small molecules for congenital hyperinsulinism [2]. A long-term study of bivamelagon in hypothalamic obesity is registered as NCT07156578 [9].
A note on scope: this page describes what has been published about an FDA-labeled drug for rare conditions. It is not medical advice, and nothing here should be read as suggesting a dose, a switch, or a treatment decision. Those belong with a prescriber who knows the individual case.
Sources
- US Food and Drug Administration. IMCIVREE (setmelanotide) injection, prescribing information. March 2026.
- Rhythm Pharmaceuticals. Rhythm Pharmaceuticals Announces FDA Approval of IMCIVREE (setmelanotide) for Patients with Acquired Hypothalamic Obesity. March 19, 2026.
- IMCIVREE (setmelanotide). Home page for patients and caregivers.
- AJMC. FDA Approves Setmelanotide for Adult and Pediatric Patients With Acquired Hypothalamic Obesity. March 20, 2026.
- ClinicalTrials.gov. A Trial of Setmelanotide in Acquired Hypothalamic Obesity (NCT05774756).
- PubMed. Efficacy and safety of setmelanotide in patients with Bardet-Biedl syndrome and Alström syndrome: a phase 3 trial.
- PubMed. Efficacy and safety of setmelanotide in individuals with severe obesity due to LEPR or POMC deficiency: phase 3 trials.
- Drugs.com. Imcivree Prices, Coupons, Copay Cards & Patient Assistance.
- ClinicalTrials.gov. A Long-Term Study of Bivamelagon in Participants With Hypothalamic Obesity (NCT07156578).
- DailyMed. IMCIVREE (setmelanotide) solution, drug label information. Updated April 1, 2026.
Frequently asked questions
Is Imcivree the same kind of drug as Ozempic or Zepbound?
No. Imcivree is a melanocortin 4 (MC4) receptor agonist that acts on a hypothalamic pathway, not on incretin receptors. The label states it is not indicated for general (polygenic) obesity, and the sources reviewed here do not report any head-to-head trial against Ozempic, Wegovy, or Zepbound.
Can someone with ordinary obesity take Imcivree?
No. The FDA label limits Imcivree to acquired hypothalamic obesity (age 4 and older), Bardet-Biedl syndrome, and genetically confirmed POMC, PCSK1, or LEPR deficiency (age 2 and older). It explicitly excludes general polygenic obesity and obesity from other genetic syndromes, where it would not be expected to be effective.
How much weight did patients lose in the trials?
In the 142-patient TRANSCEND trial in acquired hypothalamic obesity, BMI fell 15.8% on setmelanotide versus a 2.6% rise on placebo over 52 weeks (p<0.0001), a -18.4% placebo-adjusted reduction by Rhythm's release; AJMC reported slightly different figures. In Bardet-Biedl syndrome, 32.3% of patients age 12 and older with BBS lost at least 10% of body weight after 52 weeks of treatment.
Does Imcivree really darken skin, and is it permanent?
Yes, skin hyperpigmentation, darkening of existing moles, and new moles are recognized effects, and a full body skin exam is recommended before and during treatment. Patient materials from the manufacturer state these pigment changes go away after stopping the drug.
How is Imcivree injected and how often?
Imcivree is injected under the skin once daily from a 10 mg/mL multiple-dose vial. As label background only — dosing decisions belong to a prescriber — the maintenance dose for patients age 6 and older across all indications is 3 mg (0.3 mL) once daily, with lower starting doses that vary by indication and age. Detailed Instructions for Use come with the product.
What ages can take Imcivree?
The label covers age 4 and older for acquired hypothalamic obesity and age 2 and older for Bardet-Biedl syndrome and POMC, PCSK1, or LEPR deficiency. It is not known whether Imcivree is safe and effective in children under 2 years of age.
What does Imcivree cost, and does insurance cover it?
No list price could be verified for this page, and no dollar figure from the manufacturer or the FDA label could be confirmed. Rhythm's InTune support program offers insurance navigation assistance at treatment initiation and can be reached at patientsupport@rhythmtx.com. Cost and coverage questions should go to the manufacturer and the patient's insurer.
Is genetic testing required before starting?
For POMC, PCSK1, or LEPR deficiency, yes — patient materials state a provider should order a genetic test to confirm the deficiency before starting, and the label covers only variants interpreted as pathogenic, likely pathogenic, or of uncertain significance. Acquired hypothalamic obesity and BBS are diagnosed clinically, with genetic confirmation considered in BBS patients under 6.
This article summarizes FDA labeling, published research and company information current as of September 14, 2026. It is not medical advice and does not replace a conversation with your own healthcare provider. How we research and verify.