(NewsNation) — European regulators are investigating the increased risk of suicidal ideation among users of Novo Nordisk’s Ozempic and Wegovy, drugs that have recently shot up in popularity for weight loss.

The European Medicines Agency is looking into adverse events raised by the Icelandic Medicines Agency, including two cases of suicidal thoughts in those who used Ozempic, a diabetes drug that contains the active ingredient semaglutide, and Saxenda, the regulator said.

Another patient on Saxenda, Novo’s earlier and less effective weight-loss drug that contains the active ingredient liraglutide, reported thoughts of self-injury, the agency said.

One doctor and weight loss expert says since the drug works by targeting cravings, it makes sense that there are other mental impacts.

“We know for a fact that Ozempic is crossing the blood-brain barrier and affecting the dopamine releases on your cravings to kind of prohibit you from wanting to eat more, binge more,” Dr. Arvind Chakravarthy said. “So we know it’s working on the brain, so for every positive effect you have, you’re gonna probably have a negative effect.”

Another doctor stressed the importance of “lifestyle interventions” along with the use of Ozempic.

“This drug is coming in and basically compounding the problem,” said Dr. Nathan Goodyear. “Yes, it can help sugar control, but the actual approval of this was with lifestyle interventions, but only if the Metformin failed. So the issue is it’s been used out of proper context.”

Ozempic and Wegovy, which also contained semaglutide, boomed after going viral on TikTok for helping people lose weight. Ozempic is used to treat diabetes, while Wegovy is an FDA-approved weight loss drug.

The surge in popularity has resulted in shortages, and Novo Nordisk is suing companies it alleges are making knockoffs.

Research and testing of pill versions of Ozempic and Wegovy, which are currently administered by injection, is also underway.

Novo Nordisk said patient safety was top priority and it treated all reports about adverse events very seriously. Its own safety monitoring so far found no “causal association” between the self-harming thoughts and the drugs, it said in a statement.

While the label for both drugs in Europe does not list suicidal thoughts as a side effect, the prescribing information for Wegovy in the Untied States recommends patients are monitored for suicidal thoughts.

Reuters contributed to this story.