The use of glucagon-like peptide (GLP‑1) weight-loss drugs, which mimic the action of semaglutide in the human body by acting as ‘receptor agonists’ (effectively reducing appetite and blood sugar), has exploded in recent years, driven in part by a growing obesity epidemic in Western nations. Among the increasingly popular weight-loss drugs are semaglutide products such as Wegovy, Ozempic, and Rybelsus; tirzepatide (marketed generally as Mounjaro, and as Zepbound in the U.S.); and liraglutide (Saxenda). Many have been in circulation for decades, principally as drugs used in the treatment of diabetes. Their use in treating obesity has, however, been recognised in the past 5 to 10 years, in conjunction with experimental secondary uses for many of these drugs, such as treatment of dementia, Parkinsons, and autoimmune conditions. This blog explores how the rising use of various GLP‑1 medicines to reduce obesity and promote weight management may have a significant impact on Casualty insurance and reinsurance.

In most territories, including in the U.S., the EU, and the UK, these medicines are available only by prescription, and their use remains regulated. They are intended for specific clinical use rather than for cosmetic weight loss. Although their use will doubtless prove beneficial in promoting good public health, they come with a potential battery of side effects. Despite these side effects, use of these drugs has skyrocketed, with some estimates suggesting 12% of U.S. adults are now taking them.¹ Recent introduction of the drugs in pill form rather than as a weekly injection is expected to increase their use significantly.

The increased use of weight-loss drugs has similarly increased the scale at which claims exposure may accumulate across prescribing, dispensing, and monitoring chains, with products liability issues and medical errors in prescribing the drugs and monitoring their appropriate use uppermost in liability (re)insurers’ minds.

The legal significance of weight-loss medications is not confined to the pharmacology of the drugs themselves. Risks also arise from how the medication gets into the hands of consumers. The market for these drugs now includes state healthcare providers, private clinics, online prescribers, pharmacies, grey-market or counterfeit suppliers, and on‑line prescription suppliers. The diverse roster of suppliers creates multiple potential duties of care, and multiple possible defendants. A claimant alleging injury after taking a GLP‑1 medicine may bring a claim against the manufacturer for defective warnings or a defect in the product itself, against a clinic for negligently prescribing the drug, against a pharmacy for unsafe dispensing, or against an online platform for inadequate screening or verification.

Side Effects – Known Unknowns, and Unknown Unknowns

As the use of these products becomes more widespread, knowledge of actual or potential side effects is becoming more common: Vomiting, diarrhoea, gallbladder disease, pancreatitis, and rarely NAION (non-arteritic anterior ischemic optic neuropathy) – often described as an "eye stroke" leading to sudden loss of vision – have all been reported following the use of semaglutide products. In June 2025, the Pharmacovigilance Risk Assessment Committee (PRAC), part of the European Medicines Agency, concluded that NAION is a very rare side effect of semaglutide medicines and recommended that product information be updated to reflect the potential for the condition.² In February 2026, the Medicines and Healthcare products Regulatory Agency in the UK also warned that privately prescribed semaglutide may not appear in a patient’s medical history, which has obvious implications for diagnosis, emergency treatment. and later litigation.³ In September 2025, the U.S. Food and Drug Administration (FDA) announced regulation to prevent misleading advertising direct to consumers.⁴

The widespread use of these drugs for weight loss remains, comparatively, in its infancy. Identified side effects represent the current knowns, others remain unknown. Historically, the mainstreaming of certain pharmaceuticals has taught us that whether accurate or not, the suggestion of more serious side effects that take longer to manifest (such as cancers or thyroid conditions) can give rise to mass tort litigation, significantly impacting manufacturers’ insurance covers for years after the drug is certified as being safe for public use. Furthermore, insurers and reinsurers will need to consider the wider environment in which these drugs are prescribed: Although they should only be prescribed by medical professionals, other means of acquiring the drugs may emerge. celebrity endorsements and social media promotions mean that unscrupulous medical practitioners may be tempted to offer these drugs without appropriate consultation or to patients who would otherwise not qualify for their use. Use of the drugs over the longer-term should be reduced proportionately to the amount of weight lost, but on‑line consultations, hoarding by individuals, or unscrupulous practitioners could give rise to users taking significantly higher doses than is recommended or safe. Additionally, off-brand ‘wellness compounds’ mimicking the effects of GLP‑1 drugs, or even genuine pharmaceuticals attempting to copy their effects without undergoing the appropriate testing, create hazards for (re)insurers who may be offering cover which unwittingly extends across these activities. For casualty reinsurers, that combination of widespread use and a growing appreciation of the risks of accessing and using GLP‑1 drugs will inform the way that they respond to the risks posed by the use of these drugs in the future.

How Might Liability Arise?

Claims could arise around weight-loss drugs from a variety of sources: retail pharmacy portfolios, private medical and wellness providers, online healthcare intermediaries, distributors, or manufacturers based in the U.S., EU, UK, or further afield.

The practical implication is that losses impacting reinsurers may arise either from a single large pharmaceutical catastrophe, such as the identification of long-term and harmful, unanticipated side effects from regular use of the drugs, or from a series of medium-sized bodily injury and products claims arising from the same underlying commercial trend which aggregate sufficiently to impact reinsurers. For example, if several private clinics or digital pharmacy insureds prescribe a drug in the same way, then a systemic failure in screening or consent could produce a cluster of claims across a treaty year. Casualty reinsurance is sensitive to frequency, attachment, aggregation, and the quality of cedants’ operational controls. In other words, GLP‑1 exposure is not only about what was prescribed; it is about how the treatment was offered, delivered, and monitored.

Litigation is already underway in the U.S.: nearly 3,000 plaintiffs have already joined a Multi-District Litigation (MDL) in Pennsylvania, where allegations of negligence are being levelled against manufacturers, suggesting that they failed to warn of the dangers and side effects of taking the drugs, that risks were concealed from users, that the design of the drugs themselves caused harm and was itself negligent as well as a number of other potential courses of action.

Europe is less litigious at scale but is more regulatorily driven. The EMA’s 2025 conclusion on NAION and the UK’s Medicines and Healthcare Products Regulatory Agencies’ (MHRA) 2026 UK update are important because they give claimant lawyers a regulatory foothold for arguing that the risk was known sufficiently early to require stronger warnings, better monitoring, or more conservative patient selection.

A claimant may argue that the insured owed a duty to carry out a meaningful assessment before prescribing or dispensing, to provide adequate warnings about side effects, to ensure follow‑up, and to direct patients to urgent care when symptoms escalated. Publicly available legal commentary on GLP‑1 claims repeatedly identifies these fault lines: inadequate patient screening, weak checks on contraindications, failure to obtain informed consent, and lack of ongoing monitoring are all cited.⁵

Additionally, implications for liability covers for the design of the drugs themselves and the way in which they were given to patients should give providers of Directors and Officers (D&O) cover reason to be cautious. Opioid litigation in the U.S. has consistently sought to level accusations at the senior officers of drug manufacturers that the risks of opioid medications were deliberately downplayed, leading to more being prescribed and higher rates of addiction and harm.⁶ Weight-loss drugs do not appear to be addictive, but executives should be cautious about the ways in which their products are brought to market and passed into the hands of consumers.

How Should (Re)Insurers Respond?

In seeking to understand the impact of the use of weight-loss drugs across current and future portfolios as an emerging trend, practical options include asking ceding insurers detailed questions about online prescribing, remote triage, clinical governance, patient follow‑up, warning language, pharmacy verification, storage controls, and counterfeit-risk mitigation. Attention to these details will be key to distinguish between cedants whose book is geared towards general liability and those whose book contains meaningful products, pharmacy, telehealth, or private-clinic exposure.

Weight-loss drugs may not generate one large headline loss, but they might instead create a sustained run of mixed liability claims, with significant defence costs and increasing aggregation risk. The U.S. MDL illustrates the litigation potential; the EMA and MHRA warnings show that regulatory scrutiny is already in place; and worldwide, expanding obesity-treatment pathways show that exposure is likely to grow rather than diminish. This landscape should prompt sharper underwriting questions, stronger claims intelligence, and a renewed focus on the operational quality of cedants writing pharmacy, healthcare, private-clinic, and products business.