FDA Warns of Kidney Stone, Injury Risk in Use of OTC Weight-Loss Drug Orlistat

The FDA updated labeling on the OTC weight-loss drug Alli (orlistat) to urge any patient that experienced kidney disease or kidney stones to seek advice from a provider before consuming the product, according to the FDA.¹

“The FDA's recent labeling update for OTC orlistat serves as an important reminder that ‘over-the-counter’ does not necessarily mean safe or appropriate for everyone,” Hailey Choi, PharmD, BCACP, CDCES, associate professor of pharmacy practice at the Massachusetts College of Pharmacy and Health Sciences, told Drug Topics®. “In the obesity management space, many patients assume that medications available without a prescription carry minimal risk, but that is not always the case.”

Pharmacists, as the most accessible frontline health care providers, are now being called upon to play a more active role in guiding patients through the complexities of the OTC weight-loss landscape, according to the Journal of International Crisis and Risk Communication Research.²

The FDA’s recent reevaluation of safety signals was prompted by reports of acute kidney injury and calcium oxalate nephrolithiasis—which leads to kidney stones.¹

In a review of data from the FDA Adverse Event Monitoring System and medical literature, the agency identified 12 cases of severe kidney complications associated with orlistat use. Of these cases, 8 patients required hospitalization and 5 required dialysis, underscoring that while these events are rare, the severity is substantial.

READ MORE: Some Providers Prescribe Unapproved Retatrutide for Weight-Loss at Alarming Rate

The clinical implications for pharmacists are significant because the risk of kidney injury does not appear to be dose dependent. Although orlistat is a 60-milligram OTC capsule, its prescription-strength counterpart, Xenical, is 120 milligrams.¹

The FDA noted that the difference in dietary fat absorption inhibition between these 2 doses is only 5%, meaning the risk of developing oxalate crystals in the kidneys exists regardless of whether the patient is taking the nonprescription or prescription version. This makes the pharmacist’s role in screening for pre-existing kidney disease or a history of kidney stones during the point of sale vital for preventing adverse outcomes.^1,2

Beyond the newly highlighted kidney risks, orlistat’s mechanism of action presents ongoing management challenges. As a lipase inhibitor, orlistat works in the digestive tract to block the work of enzymes that break down dietary fat.^1,3

This results in approximately 25% of consumed fat passing through the body undigested, which often leads to disruptive gastrointestinal adverse effects such as oily spotting, flatulence with discharge, and fecal urgency. Furthermore, this process can reduce the absorption of fat-soluble nutrients, including vitamins A, D, E, and K, as well as beta-carotene.^3-5

Pharmacists should counsel patients to take a multivitamin at bedtime or at least 2 hours after their last dose of orlistat to mitigate these nutritional deficiencies, according to the Mayo Clinic.³

“Orlistat has modest weight-loss efficacy compared with newer evidence-based obesity medications, and its use is associated with several important safety considerations,” continued Choi. “Orlistat also has clinically significant drug interactions, including with warfarin, cyclosporine, levothyroxine, and certain antiepileptic medications, which may affect treatment outcomes or patient safety.”

The historical context of orlistat is also relevant for practitioners. Despite being the only FDA-approved OTC weight loss aid currently available in the US, the drug has faced repeated calls for a ban by consumer watchdog groups like Public Citizen due to concerns over liver damage, pancreatitis, and kidney stones.^4,6

Although the Mayo Clinic notes that a 2010 safety review found no conclusive evidence that orlistat caused reported liver injuries, the drug’s labels were nevertheless revised to include warnings for symptoms like jaundice and brown urine.³

In the current pharmaceutical climate, patients may be drawn to orlistat because it is far more affordable and widely available than the highly sought-after GLP-1 receptor agonists. Despite medications like semaglutide and tirzepatide having redefined weight-loss expectations, often helping patients lose between 15% and 22.5% of their body weight, they frequently carry monthly costs exceeding $1000, as Westlake Dermatology states.⁵

In contrast, orlistat typically produces modest results, with patients losing an average of only 5.7 pounds more in 1 year than those who only diet and exercise.^3,5

For pharmacists, the primary goal remains enhancing patient outcomes through individualized counseling. Utilizing technology like electronic health records can help pharmacists track a patient’s medical history to identify contraindications, such as a history of organ transplants or the use of cyclosporine, before a patient starts an orlistat regimen.^2,3,6

When patients present with symptoms like back or groin pain, painful urination, or leg swelling, pharmacists must be prepared to advise them to stop the medication immediately and seek medical evaluation for potential kidney injury.^1,6

By active engagement and reporting any new adverse events to the FDA MedWatch program, pharmacists can ensure that the self-care of weight loss remains safe for the millions of Americans seeking pharmaceutical assistance, whether prescription- or OTC-based.^1,2

“The FDA's warning regarding the risk of kidney injury further highlights the need for caution. Patients considering OTC weight-loss products should discuss their goals, medical history, and current medications with a pharmacist or other health care professional before starting treatment,” concluded Choi. “Obesity is a chronic disease that often requires individualized management, and even nonprescription therapies should be used under appropriate professional guidance to maximize benefits and minimize harm.”

READ MORE: Obesity Management Resource Center

REFERENCES

1. FDA approves labeling changes for alli (orlistat) to warn of risk. FDA. June 10, 2026. Accessed June 10, 2026. https://www.fda.gov/drugs/drug-safety-communications/fda-approves-labeling-changes-over-counter-otc-weight-loss-drug-alli-orlistat-warn-risk-kidney

2. Al-Dosari DF, Al-Dosari DF, Al-Massifri HSM, et al. Enhancing patient outcomes: the role of pharmacists in OTC drug selection and counseling. J Int Crisis Risk Commun Res. 2024. Accessed June 10, 2026. https://jicrcr.com/index.php/jicrcr/article/download/1132/903/5055

3. Alli weight-loss pill: Does it work? Mayo Clinic. April 9, 2024. Accessed June 10, 2026. https://www.mayoclinic.org/healthy-lifestyle/weight-loss/in-depth/alli/art-20047908

4. Salahi L. Weight loss drugs: public citizen calls for ban on alli, Xenical. ABC News. April 14, 2011. Accessed June 10, 2026. https://abcnews.com/Health/w_DietAndFitness/weight-loss-drugs-consumer-watchdog-calls-ban-alli/story?id=13376523&utm_source=chatgpt.com

5. Gordon J. Here’s how GLP-1’s compare to other weight loss medications. Westlake Dermatology. September 9, 2025. Accessed June 10, 2026. https://www.westlakedermatology.com/blog/glp-1-vs-other-weight-loss-medications/

6. Roeloffs MW. FDA warns alli—an over-the-counter weight loss pill—could cause fatal kidney problems. Forbes. June 10, 2026. Accessed June 10, 2026. https://www.forbes.com/sites/maryroeloffs/2026/06/10/fda-warns-alli-an-over-the-counter-weight-loss-pill-could-cause-fatal-kidney-problems/