FDA orders vision loss risk added to weight-loss pen labels

The FDA, the U.S. agency that regulates medicines and is the counterpart of Anvisa in Brazil, ruled on Monday (9) that all manufacturers of GLP-1 class drugs, the pens used for diabetes and weight loss, must add a warning to the label about a possible increased risk of vision loss.

The problem is nonarteritic anterior ischemic optic neuropathy, known by the acronym NAION. It occurs when blood reaches the optic nerve with less force. The typical symptom is sudden vision loss, without pain, almost always in one eye, and the damage can be permanent. There is no proven treatment.

The decision applies to the entire class, which includes semaglutide drugs such as Ozempic and Wegovy, and tirzepatide drugs such as Mounjaro. The warning goes into the warnings and precautions section of the label.

The FDA analyzed 126 clinical studies with these drugs. Among people using the pens, there were 6.4 cases per 100,000 people followed for one year. Without the drug, there were 3.8 cases. The complication remains rare, and the agency did not ban sales or state that the medicines cause the disease. Diabetes on its own also increases the risk.

The FDA's guidance is for doctors and patients to discuss this risk before and during treatment. For those with a confirmed diagnosis, the recommendation is to consider stopping the drug, unless the benefits are clearly greater. Experts note that, for most patients, the gains in diabetes and weight control still outweigh the risks.

In Brazil, in June 2025, Anvisa requested that labels for semaglutide medicines begin listing NAION as a very rare adverse reaction. The Brazilian agency's guidance is to stop use if the problem is confirmed.

The message for people using the pens is the same in both countries: if you experience any sudden loss or rapid worsening of vision, seek medical care right away and tell them you use the medication. No one should stop or change treatment on their own, without talking to their doctor.