After spending a lengthy career at a smaller pharmaceutical firm, Kogan joined Schering-Plough in 1982. Throughout the next several years, he was a part of a group of executives that helped raise revenues from $1.8 billion in 1982 to $4.5 billion in 1994. Kogan continued the same tradition when he assumed leadership of the company, investing heavily in its antihistamine products, which include Claritin, and making selective strategic acquisitions, including the animal health division of Mallinckrodt.