By October 1976, the U.S. Food and Drug Administration (FDA) Endocrinology and Metabolism Advisory Committee recommended phenformin be removed from the market.

[2] In 1977, 385,000 patients with early-stage diabetes were taking phenformin in the U.S.. Ralph Nader's Health Research Group put the U.S. government under pressure to ban the drug.

[3] As of 2008, phenformin was still legally available in Italy, Brazil, Uruguay, China, Poland, Greece and Portugal and cases of phenformin-induced lactic acidosis continued to be reported worldwide.

[7] Phenformin hydrochloride is a white crystalline powder, with a melting point of 175–178 °C; it is soluble at 1 in 8 parts of water and 1 in 15 of ethanol, and practically insoluble in chloroform and ether.

[citation needed] Phenformin is less polar and more lipid soluble and exhibits a higher affinity for mitochondrial membranes than metformin.