Semaglutide Plus Niacin for Lung Fibrosis

A rat study published in Toxicology and Applied Pharmacology on 19 September 2026 found that adding nicotinic acid, a form of vitamin B3, to semaglutide produced stronger protection against lung scarring than semaglutide alone, in animals given a lung-damaging chemotherapy drug called bleomycin^[1]. The researchers tied the extra benefit to restoring a cellular pathway called NAD+/SIRT1-FOXO3a-Nrf2, which helps cells manage oxidative stress, and to dialling down a separate inflammation and scarring pathway called NF-kB/TGF-beta^[1]. This is preclinical work done entirely in rats. It does not show that semaglutide, alone or combined with a B vitamin, treats or prevents lung disease in people, and nothing here changes what semaglutide is currently approved to do.

The paper, credited to Mo'men, Saber, Amer and El-Kashef, sits inside a long-running research tradition: giving rats bleomycin to model pulmonary fibrosis, the scarring disease that gradually stiffens lung tissue and makes breathing harder over time. Bleomycin is itself an approved chemotherapy drug in humans; at controlled research doses in animals it reliably injures the lungs and sets off a fibrotic response, which is why it has been the most common way to study candidate pulmonary fibrosis treatments for decades^[2].

What the researchers actually did

Over 21 days, the team gave rats bleomycin to trigger lung injury, then treated separate groups with semaglutide alone, nicotinic acid alone, or the two combined^[1]. They then measured tissue markers along two pathways: NAD+/SIRT1-FOXO3a-Nrf2, the cell's built-in antioxidant defence system, and NF-kB/TGF-beta, a pathway that drives inflammation and drives the buildup of scar tissue^[1]. The published summary does not report the exact milligram doses used, and none of it should be read as a comparison to any dose given to a person taking semaglutide for diabetes or weight management.

Why nicotinic acid and NAD+

Nicotinic acid is one of two chemical forms of niacin (vitamin B3), and the body uses it to build NAD+, a coenzyme every cell needs to convert food into usable energy and to repair damaged DNA. NAD+ levels fall with age and with cellular stress, and a growing body of research has looked at whether restoring NAD+ can blunt age- and stress-related tissue damage^[3]. SIRT1 is an enzyme that only works when NAD+ is available, and once active it switches on FOXO3a, a stress-response protein, which in turn activates Nrf2, the gene program that ramps up the cell's own antioxidant defences. The idea behind combining nicotinic acid with semaglutide was to feed that whole chain more of the raw material, NAD+, it needs to run.

What the combination did that semaglutide alone did not

In the bleomycin-injured rats, the combination group showed more strongly restored NAD+/SIRT1-FOXO3a-Nrf2 markers and greater suppression of the NF-kB/TGF-beta inflammatory and fibrotic markers than the semaglutide-only group^[1]. The authors' own conclusion, quoted directly, is that "NA-driven NAD+ metabolic support can amplify the protective profile of SEMA in experimental pulmonary fibrosis," while noting that further work is needed to confirm the underlying mechanism and any relevance to the clinic^[1]. That is a mechanistic finding in one animal model, not a treatment result.

Semaglutide's approved uses today

Semaglutide is currently authorised as a prescription medicine for type-2 diabetes and chronic weight management, sold as Ozempic, Rybelsus and Wegovy, and none of those authorisations cover pulmonary fibrosis or any other lung disease. Details on its approved indications, dosing programmes and regulatory status are on our semaglutide peptide page. Papers like this one are part of a wider pattern of researchers testing whether a widely prescribed metabolic drug also affects inflammation and scarring in other organs, a question that is being asked about several tissues, not just the lungs.

What this study does not show

It does not show that semaglutide, with or without nicotinic acid, prevents or treats pulmonary fibrosis in humans. The bleomycin model is the most widely used tool for this kind of research precisely because it produces a fast, reliable fibrotic injury, but a fast chemical injury in a rat lung is not the same disease process as idiopathic pulmonary fibrosis in a person, which typically develops slowly over years and often without a known cause. It is not a dosing guide of any kind; the amounts given to the rats were experimental research exposures, not a human-equivalent regimen. And it is one paper from one research group that has not yet been independently repeated, so any specific numbers or mechanistic claims should be treated as preliminary until other labs test the same combination.

If you take semaglutide

This paper is not a reason to add niacin or any other supplement to a semaglutide regimen in the hope of a lung benefit, and it is not a reason to worry about your lungs if you are already taking semaglutide for an approved indication. Pulmonary fibrosis is not a reported semaglutide side effect, and this rat study does not change that. If you are managing type-2 diabetes or weight with semaglutide and have any respiratory symptoms or questions, that conversation belongs with the clinician who knows your history and your labs, not with a preclinical rodent paper^[4].

This article is for educational and journalistic purposes only and does not constitute medical advice. Semaglutide is a prescription medicine, not a supplement, and it is not approved to treat or prevent pulmonary fibrosis or any other lung disease. Always consult a qualified healthcare professional before starting, stopping, or combining any medicine or supplement. PeptideMethods.com does not sell, distribute, or facilitate the sale of any peptide product.