FDA says GLP-1s must include warning label over potential blindness

Currently there are around 100 GLP-1 lawsuits related to a rare eye condition called nonarteritic anterior ischemic optic neuropathy (NAION). This condition, which is sometimes referred to as an "eye stroke," can cause sudden vision loss in one or both eyes due to a lack of blood flow in the optic nerve.

NAION is relatively rare, with only around two to 10 out of every 100,000 people ages 50 and over getting the disease every year. Although the exact cause of the condition isn't clear, health conditions that can disrupt blood flow to the eye include diabetes, low/high blood pressure, anemia, sleep apnea, and migraines.

In the lawsuits, plaintiffs argue that Eli Lilly and Novo Nordisk knew or should have known about the risk of NAION and didn't properly warn patients. In response to the lawsuits, a spokesperson for Novo said the allegations are without merit and that the company is vigorously defending against them. Eli Lilly said that patient safety is the company's top priority and that it will "continue to review data, including any data regarding ophthalmic issues."

On Monday, FDA said that "there is a potential increased risk of rare NAION" in people taking GLP-1s and required that all makers of GLP-1s add a warning label about the risk of NAION.

FDA said it started looking into a possible link after a 2024 study published in JAMA Ophthalmology found diabetes patients prescribed semaglutide were four times more likely to develop NAION than those not prescribed the drug.

The agency said it reviewed reports of side effects that were submitted to its adverse event monitoring system and analyzed data from multiple clinical trials, finding that cases of NAION have been reported for all GLP-1 drugs currently on the market. However, scientists at FDA were unable to identify a mechanism for how GLP-1s could increase the risk of NAION.

Manjot Gill, an ophthalmologist at Northwestern Medicine, said that while FDA's warning label mandate is appropriate, there's little cause for immediate concern as NAION is extremely rare.

"We don't want patients to really get overly concerned and anxious and to stop these medications," Gill said. "It's fine to issue this warning more so for public awareness so that patients, should they experience any kind of change in vision, that they do actually go and seek the care of an eye provider."

Other GLP-1 side effects to know about

The risk of NAION adds to the growing list of common and rare side effects that have reportedly been associated with GLP-1s.

Many of the most common GLP-1 side effects are fairly benign and are worse when a patient is starting treatment and after their dose is increased. Some of these side effects include:

However, some less common but potentially more serious side effects have also been linked to GLP-1s. These include:

• Loss of muscle mass: Some consumers have reported unintended muscle loss after starting GLP-1s. Peter Attia, a physician who focuses on the science of longevity, said in an Instagram post that "almost every patient we put on this drug [semaglutide] has lost muscle mass at a rate that alarms me."
• Scurvy: A review from researchers at the University of Newcastle published earlier this year analyzed findings from 41 clinical trials on GLP-1 and GIP receptor agonist medications over the last 17 years and found that the appetite-suppressing properties of GLP-1s and other weight-loss medications could lead to vitamin deficiencies. As a result, there have been anecdotal reports of GLP-1 patients developing scurvy, which is caused by a lack of vitamin C.
• Miscarriage and birth defects: FDA recommends that patients discontinue use of GLP-1s at least two months before getting pregnant due to potential risks of miscarriage and birth defects.
• Severe mental health issues: According to FDA's adverse event reporting system, there have been over 480 reports of patients experiencing anxiety, depression, or suicidal thoughts while on semaglutide.
• Pancreatitis: GLP-1s have been linked to pancreatitis, a serious inflammation of the pancreas that can cause severe, persistent abdominal pain, nausea and vomiting, and jaundice. If left untreated, the condition can be life-threatening.
• Nail detachment: A study presented earlier this year at the European Academy of Dermatology and Venereology's 2026 meeting found that GLP-1 users have an increased risk of onycholysis, which is the separation of fingernails or toenails, and an increased risk of dyschromia, or nail discoloration.
• Osteoporosis and gout: A study published earlier this year found that GLP-1s may increase a person's risk of osteoporosis and gout. Of the 146,000 patients studied, roughly 4% of those taking GLP-1s developed osteoporosis compared to 3% of those not taking the drugs, and 7.4% of GLP-1 users developed gout compared to 6.6% of non-users.
• Dental issues: Some reports have surfaced about a side effect of GLP-1s known as "Ozempic teeth," with symptoms ranging from dry mouth to more severe gum and dental issues that appear to largely be rooted in dehydration and reduced saliva production.
• Hair loss: A study of around 50,000 people published in the BMJ earlier this year found that using GLP-1s was associated with a 37% increased risk of alopecia hair loss compared to the use of SGLT-2 inhibitors, another type of diabetes drug, and a 68% increased risk of hair loss compared to use of diabetes drugs called DPP-4 inhibitors.
• Acute kidney damage: While GLP-1s have been shown to have a beneficial effect on the kidneys, in some rare cases, acute kidney damage has been reported, mainly in people with severe side effects that have led to dehydration.
• Thyroid C-cell tumors: All GLP-1s come with a boxed warning for the potential risk of thyroid C-cell tumors, based on studies in animals. However, the risk has not been confirmed in humans.