Pharmacia was originally a government owned Swedish pharmaceutical company. Sold to private interests in the 1990s, it was first merged with the American pharmaceutical company Upjohn and headquartered in London. The merged company Pharmacia & Upjohn was there after bought by the American bioindustry and medical company Monsanto. The resulting conglomerate took the name of Pharmacia Inc and spun off its agricultural chemical division under the name Monsanto.
In 2004, the allergy-diagnostic division of legacy Pharmacia was sold of. 'Pharmacia Diagnostics' is now the only remaining use of the Pharmacia business-name.