The U.S. Food and Drug Administration does not issue a blanket ban on stem cell therapies, but it strictly regulates them as biological drugs, requiring rigorous clinical trial data to prove safety, purity, and efficacy before granting commercial approval. Many unproven stem cell treatments offered at unauthorized clinics fail to receive approval because they lack adequate scientific evidence, standardized manufacturing protocols, or well-controlled randomized clinical trials demonstrating reproducible therapeutic benefits. Furthermore, unverified procedures can pose serious health risks, including tumor formation, severe immune reactions, and transmission of infections, prompting the regulatory agency to crack down on unauthorized marketing while approving legitimate, thoroughly tested products like specific bone marrow or CRISPR-modified cellular interventions.