GLP-1 drugs, like Ozempic and Mounjaro, are dominating headlines for their ability to drive weight loss. What most people don't know is that despite this recent attention, they’re not new. They've been researched since the 1980’s and used to treat type 2 diabetes for nearly two decades.
But the weight loss story isn't the most interesting thing about them.
When researchers look beyond it - at the immune system, the brain, and the reproductive system - a different picture begins to emerge. One that may matter far more to the millions of women living with endometriosis and PCOS, conditions that remain chronically undertreated despite their prevalence.
This article covers the emerging evidence: what studies are finding about GLP-1s and reproductive function in PCOS, and what early signals suggest about their potential impact in endometriosis. Importantly, many of these effects are not a downstream effect of losing weight.
This article is for informational purposes only and reflects a summary of current research that is referenced at the end of this article. It is not medical advice. If GLP-1 drugs are something you're curious about, we'd always recommend speaking with your doctor before making any decisions about your health.
What are GLP-1 drugs, and what do they do in the body?
GLP-1 - glucagon-like peptide-1 - is a hormone naturally produced in the gut after eating. It plays a key role in regulating blood sugar and appetite through three main mechanisms:
◈ Stimulating insulin release to lower blood sugar after a meal
◈ Suppressing glucagon, the hormone that would otherwise push blood sugar higher
◈ Slowing gastric emptying, so food moves through the stomach more gradually - keeping you fuller for longer.
GLP-1 drugs are synthetic analogues engineered to mimic this hormone. They bind to the same receptor but, unlike the natural hormone (which is broken down quickly), they resist rapid degradation - giving them a sustained effect on appetite and blood sugar regulation.
The two most widely used drugs work slightly differently:
1. Semaglutide (Ozempic, Wegovy): a GLP-1 receptor agonist which targets the GLP-1 receptor specifically
2. Tirzepatide (Mounjaro, Zepbound): a dual GIP/GLP-1 receptor agonist; also activates a second gut hormone receptor, GIP (glucose-dependent insulinotropic polypeptide)
Plot twist: GLP-1 receptors are scattered throughout the body - including on immune cells and in the ovaries
Here's where it gets interesting.
GLP-1 receptors are expressed across a surprisingly wide range of tissues - and the implications of that are starting to become understood. Those relevant to this article?
» Immune system: GLP-1 receptors are found on macrophages, monocytes, and endothelial cells - key players in immune regulation and inflammatory responses. Activating them appears to suppress pro-inflammatory signalling, which has significant implications for conditions where chronic inflammation is involved.
» Brain: GLP-1 receptors are in the hypothalamus and pituitary - both central to the hormonal cascade governing GnRH, LH, and FSH production that regulates ovulation and the menstrual cycle.
» Reproductive system: GLP-1 receptors are in ovarian tissue and the endometrium.
And this is partly why researchers are turning their attention to endometriosis and PCOS.
PCOS and GLP-1s: Improving Reproductive Functionality
For PCOS, the human evidence on GLP-1 medications is compelling enough that they now feature in the 2023 International PCOS Guidelines, though as a conditional recommendation (1).
Polycystic ovary syndrome affects 6-20% of women of reproductive age and impacts hormonal and metabolic function. Symptoms range from irregular periods and elevated androgens, to weight gain, hair loss, and sometimes polycystic ovaries.
What's becoming increasingly clear is that GLP-1s can address PCOS through mechanisms that go beyond their known metabolic effects.
What do studies show?
Human trials of GLP-1 medications in women with PCOS have found (2):
◈ Ovulation rates of 86% in women taking GLP-1s alongside metformin - compared to 29% on metformin alone, a threefold improvement
◈ 62% of women on GLP-1s had more regular menstrual cycles, versus 28% on placebo
◈ Significant reductions in testosterone levels
These are meaningful numbers for a condition where restoring ovulation and cycle regularity remains one of the challenges.
How might they work in PCOS?
Tackling insulin resistance: Insulin resistance is a hallmark of PCOS, and GLP-1 medications improve insulin sensitivity. This matters because high insulin drives the ovaries to produce excess androgens such as testosterone - so reducing insulin resistance helps bring androgen levels down, and with both, many PCOS symptoms can be improved.
Reducing inflammation: GLP-1s reduce systemic inflammation markers - relevant because chronic low-grade inflammation in PCOS disrupts ovarian function and compounds hormonal dysregulation.
Regulating hormone signalling: GLP-1s may help regulate the LH surge that is characteristically dysregulated in PCOS - potentially through direct action on GLP-1 receptors in the hypothalamus and pituitary, the regions governing reproductive hormone output.
Improving ovarian structure and function: GLP-1 receptors are expressed directly on ovarian tissue. Animal models have shown reductions in cystic follicles and improvements in ovarian morphology with GLP-1 treatment - likely through a combination of direct receptor activity, and downstream effects of improved insulin and androgen levels.
Larger, longer-term human trials are still needed to fully characterise these effects.
Endometriosis and GLP-s: Emerging Research
Endometriosis is a systemic inflammatory disease that affects at least 10% of women worldwide. Yet treatment options remain frustratingly limited - and for many, inadequate.
Lower GLP-1 in endometriosis
A recent study has uncovered something interesting: women with endometriosis had significantly lower natural GLP-1 in their peritoneal fluid, compared to those without the disease (4). And that deficit appears to matter.
The macrophage connection
In the same study, lower GLP-1 levels correlated with reduced immune activation of peritoneal macrophages. This is important because macrophages normally help clear abnormal endometrial-like tissue.
The finding suggests that reduced GLP-1 may be part of the puzzle linked to the immune dysfunction that allows endometriosis to persist.
This raises the question: could restoring GLP-1 levels through medication boost macrophage activity back up, and therefore help the immune system fight endometriosis more effectively? This remains to be investigated.
Other ways that GLP-1s drugs could help?
This is still early-stage science, but the mechanistic rationale is building. Several theoretical pathways are worth considering
1. Reducing chronic inflammation: GLP-1s have well-established anti-inflammatory effects, including inhibition of NF-κB - a master switch for inflammation that is chronically overactivated in endometriosis. NF-κB activation helps ectopic lesions survive, drives the inflammatory cytokine environment in the peritoneal cavity, sensitises nerves to cause pain, and stimulates local estrogen production that feeds further lesion growth (5-9). GLP-1s could theoretically interrupt several of these mechanisms simultaneously to help endometriosis.
2. Combating fibrosis Endometriosis lesions develop fibrotic (scar-like) tissue that causes adhesions, organ dysfunction, and pain. GLP-1s have demonstrated anti-fibrotic properties in other organs (liver, kidney, heart) by reducing collagen deposition and tissue scarring (10). Whether this translates to endometriosis lesions remains to be studied.
Where does the evidence stand with endo?
The mechanistic evidence is promising, but human trials are still needed, and endometriosis presents complexity as a full-body disease. That said, some endo specialists are already prescribing GLP-1 drugs "off-label" (11).
It's also worth noting that the potential immunological benefits may not require the doses associated with significant weight loss, and therefore come with less side effects (12).
To be aware of:
There's a lot to consider if GLP-1s are something you're curious about. This ranges from how they might impact your relationship with food, knowing how they can be used in a way that is both safe and effective without negative side effects, and also if weight loss isn't your goal. These drugs are not currently licensed for PCOS or endometriosis. Please speak with a qualified healthcare professional who understands your current situation and full medical history before making any decisions.
References:
1. Teede et al. Recommendations From the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome. Journal of Clinical Endocrinology & Metabolism. 2023;108(10):2447–2469
2. Hoteit et al. The dual impact of GLP-1 receptor agonists on metabolic and reproductive health in polycystic ovary syndrome: insights from human and animal trials. Ther Adv Endocrinol Metab. 2025;7;16:20420188251383064.
3. Sola-Leyva et al. The hidden impact of GLP-1 receptor agonists on endometrial receptivity and implantation. Acta obstetricia et gynecologica Scandinavica.2025
4. Krasnyi et al. The Levels of Ghrelin, Glucagon, Visfatin and Glp-1 Are Decreased in the Peritoneal Fluid of Women with Endometriosis along with the Increased Expression of the CD10 Protease by the Macrophages. Int J Mol Sci. 2022 Sep 8;23(18):10361.
5. Mehdi et al. Glucagon-like peptide-1: a multi-faceted anti-inflammatory agent. Frontiers in immunology. 2023
6. Alharbi SH. Anti-inflammatory role of glucagon-like peptide 1 receptor agonists and its clinical implications. Ther Adv Endocrinol Metab. 2024 Jan 27;15:20420188231222367.
7. Hu Z, Feng Y, Liang J, et al. An update on the multifaceted role of NF-κB in endometriosis. Int J Biol Sci. 2022;18(11):4400–4413.
8. Ngabea MA, Dimeji IY. GLP-1 receptor agonists and inflammatory pathway modulation: Dual targeting of metabolic and immune dysfunction in insulin resistance. Biochem Biophys Res Commun. 2025 Nov 14;789:152822.
9. Gonzalez-Ramos R, et al. Nuclear factor-kappaB: a main regulator of inflammation and cell survival in endometriosis pathophysiology. Fertil Steril. 2012;98(3):520–528.
10. Shao S, et al. Application of glucagon-like peptide-1 receptor agonists in fibrotic diseases. Biomed Pharmacother.2022;154:113403.
11. ESSI. Treating endometriosis inflammation with GLP-1s. International Endometriosis Surgery Institute; 2025 Dec 2. Available from: https://internationalendo.com/glp1-anti-inflammatory-mechanisms-endometriosis/
12. Afrin LB, Weinstock LB, Dempsey TT, Aschenbrenner K, Blitshteyn S, Schofield JR. Utility of glucagon-like-peptide-1-receptor agonists in mast cell activation syndrome. The American Journal of the Medical Sciences. 2025.