Millions of US adults use unapproved GLP-1 drugs or alter their doses

CDC survey finds widespread GLP-1 use

Roughly one in 10 US adults, about 27 million people, used a GLP-1 medication in 2025, according to a new study by researchers at the Centers for Disease Control and Prevention. Ars Technica reports the findings are based on survey responses from more than 8,000 US adults collected between July and August 2025.

GLP-1 drugs are peptide-based medicines, meaning they are built from amino acid chains. They are approved for diabetes and weight loss, and doctors increasingly prescribe them for related chronic conditions such as cardiovascular disease and obstructive sleep apnea.

Many users change how they take the drugs

Among people using GLP-1 medications, 44 percent reported using them differently from how they were prescribed. The changes included skipping doses, delaying refills and taking smaller doses than directed.

Cost and availability drove much of this behaviour. More than half of those who modified their use said cost or access was the reason, and the problem was far more pronounced among younger users: cost was cited as a barrier much more often by adults aged 14 to 39 than by adults aged 65 or older.

Compounded versions carry extra risk

At least 23 percent of GLP-1 users took a compounded version of the drug, and a further 9 percent did not know whether theirs was compounded. Compounded drugs are made by specialised pharmacies to imitate approved medicines such as Wegovy or Ozempic, but they are not approved by the FDA, which does not review their safety, effectiveness or quality before sale.

Compounded medicines are usually cheaper and easier to obtain, but they have higher rates of preparation errors, contamination and other manufacturing problems than regulated drugs. Among users of these unapproved versions, 62 percent were not taking the medication as prescribed, compared with 36 percent of users of brand-name products.

Marketing adds to the confusion

Users may struggle to tell the difference between approved and compounded products. A 2025 study of websites selling compounded GLP-1 medications found that nearly 40 percent of the sites stated or implied the drugs were FDA-approved.

Nearly 80 percent of those sites used brand names in their advertising, which the researchers noted violates FDA regulatory standards and could mislead consumers further. Ars Technica reports the CDC authors say that, given how many people take compounded GLP-1s, understanding their safety and quality is an important public health concern.

Why it matters

The findings suggest that cost and supply barriers are pushing a large share of patients towards unregulated products and improvised dosing patterns that doctors never intended. The CDC researchers call for more research on common modifications such as dose and frequency adjustments.

Until then, readers considering a GLP-1 medication should seek a prescription through a licensed clinician and be cautious about websites that claim compounded products are FDA-approved.