Do unpleasant side effects mean the end of the hype surrounding slimming products?

The success of anti-obesity drugs may be over, as there are reports of side effects from high doses of GLP-1 drugs.

GLP-1 were originally developed to treat diabetes, but have also shown efficacy in weight loss. The field is currently dominated by Eli Lilly (NYSE: LLY), which produces Zepbound and Mounjaro, and Novo Nordisk (NVO), with Ozempic and Wegovy.

The success of the drugs has helped the stocks of both companies. NVO is up more than 40% in the past year and LLY is up more than 50%. Both stocks are not far from their 52-week highs.

But the Financial Times reported that a recent study by Roche (OTCQX:RHHBY) “showed frequent vomiting and other side effects in those who took high doses of the drugs.”

Three out of four patients injected with the highest dose of CT-388 vomited, while the oral pill produced similar side effects, the FT reported. It added that 30% of GLP-1 users stopped taking the drugs within four weeks, with many of them citing side effects, according to Blue Health Intelligence.

The drugs' popularity has led to a race to enter the market. According to a report by Morningstar and Pitchbook, as many as 16 new GLP-1 drugs could hit the market by 2029, capturing nearly a third of a potential $200 billion market by 2031.

Other players in the weight loss space include Amgen (AMGN), Pfizer (PFE), AstraZeneca (AZN), Viking Therapeutics (VKTX) and Structure Therapeutics (GPCR), while Merck (MRK) and J&J (JNJ) are potential suitors for the development of GLP-1.