Does Retatrutide Cause Low Libido or ED? What the Trial Tables Say
What retatrutide and tirzepatide trial tables report on erectile dysfunction and libido, with the limits of the screened evidence.
Research use only. This page provides scientific background and community-report context. Every compound sold here is supplied strictly for in-vitro research. Nothing on this page is a protocol, a recommendation, or medical advice.
TL;DR: an event row, an unmeasured endpoint
The question people actually type: does retatrutide cause low libido or erectile dysfunction?
What the published data say: the retatrutide trial table reports the MedDRA term “Erectile dysfunction” in 2/36 participants in its lowest arm versus 0/36 placebo through 52 weeks; that does not establish causation. [NCT04881760]
What has not been studied: there are no human data from a dedicated retatrutide sexual-function endpoint in the screened records. [ClinicalTrials.gov outcome screen, 2026-09-13]
What research communities report: in the Reddit corpus we track, 131 question posts in 12 months and 5 in the 4 to 12 Sept 2026 window matched a compound anchor near a sexual term. These are reports, not evidence of frequency; the count is an upper bound. [Internal corpus audit, 2026-09-13]
What do the retatrutide tables report about erectile dysfunction?
The posted obesity trial reports the MedDRA term “Erectile dysfunction” in its lowest study arm. The table gives participants affected over participants at risk, through 52 weeks. [NCT04881760]
In the obesity trial, the once-weekly subcutaneous study arms ran for 48 weeks; adverse events were observed through 52 weeks. [NCT04881760]
- Erectile dysfunction, n/N
- 2/36
- Comparator, n/N
- Placebo: 0/36
- Observation window
- To 52 weeks
- Erectile dysfunction, n/N
- 0/17; 0/18; 0/18; 0/18; 0/32
- Comparator, n/N
- Placebo: 0/36
- Observation window
- To 52 weeks
These are the study arms of the cited trials, not an application protocol for research vials.
The other-event table has a 5% reporting floor: a term appears when it reaches that threshold in any arm. The 2/36 entry equals 5.6%; printed zeros elsewhere do not establish a dose-response or a ranking of arms. A missing term below this reporting floor cannot be read as absence of events. [NCT04881760]
The diabetes trial's reproductive rows were “Penile swelling,” 1/13 in the dulaglutide comparator and zero in every retatrutide arm, and “Vaginal haemorrhage,” 1/16 in a retatrutide arm versus 0/23 placebo, through 280 days. [NCT04867785] Neither is a sexual-function measure; the obesity trial's other-event table has a 5% reporting floor. [NCT04881760]
The serious-event tables contained no reproductive or sexual term in the screen; those tables have no reporting floor, unlike the 5% floor for the obesity trial's other-event table. [NCT04881760; NCT04867785]
Is there a libido row anywhere in the retatrutide records?
No libido term was found in either posted record; the obesity trial's 5% reporting floor means a missing row is not a measured zero rate. The whole-record search covered libido, sexual, erectile, erection, orgasm, anorgasm, ejacul, impoten, dyspareunia, hypogonad, testosterone and arousal. [NCT04881760; NCT04867785; screen, 2026-09-13]
Only 2 of 34 registered retatrutide studies had posted results; every phase 3 TRIUMPH and TRANSCEND record lacked them. Across 333 retatrutide outcome measures, none matched the sexual-function screen. That is an endpoint gap, separate from an adverse-event reporting threshold. [ClinicalTrials.gov retatrutide search, 2026-09-13]
What do the tirzepatide and semaglutide records and labels add?
They add sparse MedDRA event rows, label searches and observational comparisons, without establishing retatrutide causation. SURMOUNT-OSA lists “Libido decreased”: 1/114 in the tirzepatide MTD_GPI1 arm versus 0/120 placebo. The observation window is not specified in the available extract. [NCT05412004]
SURPASS-CVOT reports serious “Erectile dysfunction”: 1/4744 in the tirzepatide arm versus 1/4702 dulaglutide. Another trial reports the same term in 0/113, 1/119 and 1/132 across its tirzepatide arms versus 0/117 dulaglutide, without a dose trend. Observation windows are not specified in these extracts either. [NCT04255433; NCT03861052]
The full DailyMed label texts for WEGOVY, ZEPBOUND and MOUNJARO had no matches for the sexual-term screen. Label absence is not a sexual-function assessment. [DailyMed SPL screen, 2026-09-13]
An FDA spontaneous-report analysis counted 182 male sexual-dysfunction reports from Q4 2003 to Q1 2024, with a reporting odds ratio of 0.41 versus other drugs (95% CI 0.36 to 0.48); this is reporting disproportionality, not incidence. [PMID 40240532]
A matched cohort of men with type 2 diabetes reported erectile-dysfunction risk ratios of 0.70 (0.64 to 0.76) versus sitagliptin, 0.67 (0.62 to 0.72) versus injectable semaglutide and 0.55 (0.51 to 0.59) versus dulaglutide in the tirzepatide comparison. These observational associations do not establish a causal effect. [PMID 40614622]
PeptidesDirect does not sell tirzepatide. PeptidesDirect does not sell semaglutide. PeptidesDirect does not sell dulaglutide. PeptidesDirect does not sell sitagliptin.
Has any trial measured sexual function with an instrument?
Yes, a dulaglutide crossover trial measured sexual desire, but the screened retatrutide and SURMOUNT/SURPASS records had no such endpoint. None of their 670 outcome measures matched the screen. [ClinicalTrials.gov outcome screen, 2026-09-13]
Among 24 of 26 healthy men, the dulaglutide versus placebo MGH-SFQ difference after 4 weeks was 0.58 (95% CI -0.83 to 2.00; p = 0.402), with no significant questionnaire change. Total testosterone was a measured trial variable: difference 0.9 nmol/l (-1.5 to 3.3). [PMID 39232425]
A controlled pilot study involving 83 men with obesity and metabolic hypogonadism reported higher IIEF-5 scores in the tirzepatide group at two months; testosterone was also measured. Its population and design differ from the crossover trial. A completed semaglutide hypogonadism study had no posted results, so no questionnaire conclusion follows from that record. [PMID 40604795; NCT06489457]
Why is obesity part of the picture, and what happens to testosterone?
The study populations matter: a meta-analysis reported higher baseline erectile-dysfunction odds among men with obesity versus normal-weight comparators, OR 1.60 (95% CI 1.29 to 1.98). [PMID 32002782]
Another meta-analysis pooled testosterone as a measured variable across 7 studies involving 680 participants with overweight or obesity. It reported higher total serum testosterone but could not demonstrate direct drug action; that laboratory result does not answer the desire question. [PMID 40105090]
Gelfand and colleagues proposed a theoretical GLP-1/serotonin link through the 5-HT2C route, explicitly describing their lowered-desire forecast as non-quantitative. [PMID 41404471]
Related evidence is covered in menstrual-cycle and reproductive research and heart-rate and fatigue research.
Products mentioned
Retatrutide (LY3437943) is a synthetic 39-amino-acid peptide that acts on three receptors at once: GLP-1, GIP and glucagon. Supplied as a lyophilized powder for in-vitro research, with a batch-specific third-party certificate of analysis.
Research use only. Materials sold here are supplied strictly for in-vitro research. Nothing on this page is an application protocol or medical advice.
Sources
- ClinicalTrials.gov, screened 2026-09-13. Posted retatrutide obesity results, other and serious events. NCT04881760.
- ClinicalTrials.gov, screened 2026-09-13. Retatrutide diabetes results, other and serious events. NCT04867785.
- ClinicalTrials.gov, screened 2026-09-13. Retatrutide, SURMOUNT tirzepatide and SURPASS tirzepatide record and outcome-measure searches; sexual-function and discontinuation searches.
- ClinicalTrials.gov, screened 2026-09-13. SURMOUNT-OSA, other events. NCT05412004.
- ClinicalTrials.gov, screened 2026-09-13. SURPASS-CVOT, serious events. NCT04255433.
- ClinicalTrials.gov, screened 2026-09-13. Tirzepatide trial, other events. NCT03861052.
- DailyMed, 2026-06-30. WEGOVY SPL label. Setid ee06186f-2aa3-4990-a760-757579d8f77b.
- DailyMed, 2026-09-02. ZEPBOUND SPL label. Setid 487cd7e7-434c-4925-99fa-aa80b1cc776b.
- DailyMed, 2026-09-02. MOUNJARO SPL label. Setid d2d7da5d-ad07-4228-955f-cf7e355c8cc0.
- Pourabhari Langroudi A et al., 2025, Int J Impot Res. FDA spontaneous reports of male sexual dysfunction. PMID 40240532.
- Cowart K, Murphy C, Carris N, 2025, J Diabetes Complications. Matched cohort comparison of erectile dysfunction. PMID 40614622.
- Lengsfeld S et al., 2024, EBioMedicine. Randomised sexual-desire questionnaire trial. PMID 39232425; PMC11404067.
- La Vignera S et al., 2025, Reprod Biol Endocrinol. Controlled pilot with IIEF-5 and testosterone measurements. PMID 40604795; PMC12220628.
- ClinicalTrials.gov, screened 2026-09-13. Semaglutide vs Testosterone Replacement Therapy on Functional Hypogonadism and Sperm Quality. NCT06489457.
- Pizzol D et al., 2020, Rev Endocr Metab Disord. Obesity and erectile dysfunction meta-analysis. PMID 32002782.
- Salvio G et al., 2025, Andrology. Total serum testosterone meta-analysis. PMID 40105090; PMC12569732.
- Gelfand ST, Tveit MC, Simon JA, 2026, Obes Pillars. Theoretical sexual-desire model. PMID 41404471; PMC12704374.
- PubMed and ClinicalTrials.gov, 2026-09-13. Recovery-after-discontinuation searches documented in the C036 audit.
- Internal Reddit corpus audit, 2026-09-13. Compound anchors near sexual terms in question-posts.jsonl and delta2/questions.json.
Research context for English-speaking buyers
Most of our English-speaking customers ship to the UK, Ireland, Malta or other English-as-second-language EU territories. The regulatory picture differs per country.
- Relevant authorities
- MHRA (UK, post-Brexit), HPRA (Ireland, EU-aligned), FDA Section 503A bulks list (US, restricted Cat 2 status of several peptides as of 2026)
- Customs and VAT
- EU shipments include VAT, the rate depends on the destination country; UK shipments after Brexit are now extra-EU and may attract UK VAT plus a handling fee at import
- Typical shipping window
- EU 2-4 working days, UK 4-7 working days, other international 7-14 working days, depending on customs
Research-grade peptides shipped from our EU warehouse are sold for laboratory use only and are not authorised for human or veterinary therapeutic application in any of the destination jurisdictions. US customers should be aware that the FDA Section 503A bulks list classification (and the April 2026 reclassification of twelve compounds) only governs compounding pharmacies, not direct-to-researcher imports for non-clinical work. UK buyers should declare the consignment on import and may be asked for a research justification by HMRC. We provide a CoA per batch identified by colour code rather than serial number; customs sometimes asks for this document when clearing the parcel.