FDA Issues Warning Letter to Natuzem Over Three Unapproved Drugs Sold Online from Mexico

Cross-border enforcement of unapproved drug sales is no longer a theoretical risk for foreign-based online sellers: FDA's Center for Drug Evaluation and Research (CDER) issued Warning Letter 737558 on October 26, 2026, to Natuzem, an Aguascalientes, Mexico-based operation, citing three products marketed without approved applications under section 505(a) of the FD&C Act.

The letter identifies "Testitón Extra Strong vials," "Reumofan Plus," and "Artrifan King" as unapproved new drugs. FDA's determination rests on product labeling and website claims that establish therapeutic intent under 21 CFR 201.128, including representations that the products treat arthritis, osteoporosis, bone cancer, and erectile dysfunction. None of the three products holds an approved NDA or ANDA; all therefore lack the safety and efficacy determination required before introduction into U.S. interstate commerce under 21 U.S.C. 355(a).

The review was conducted in September 2026 as part of CDER's ongoing website surveillance program. FDA explicitly noted the warning letter is not an exhaustive inventory of violations, preserving the agency's latitude to pursue additional findings. Failure to respond adequately exposes Natuzem to seizure and injunction without further notice, enforcement tools that apply regardless of the firm's physical location outside U.S. borders.

For regulatory affairs leads at international manufacturers selling or distributing into the U.S. market, the enforcement action reinforces a consistent agency posture: website claims constitute labeling evidence of intended use, and that evidence is sufficient to trigger FD&C Act jurisdiction. The geographic distance of a manufacturer does not limit FDA's reach when products enter U.S. interstate commerce. Teams conducting periodic label reviews and website audits should treat online promotional copy with the same scrutiny applied to package inserts under 21 CFR Part 201.

Natuzem's response to Warning Letter 737558 and any subsequent corrective actions will serve as a measurable indicator of how CDER's cross-border enforcement posture translates into compliance outcomes for foreign online drug sellers.

Source: FDA CDER via What's New: Drugs RSS Feed, November 3, 2026.