Shares of both companies climbed to all-time highs on the news. If they combine, Mylan and Perrigo would become one of the world's largest makers of generic and over-the-counter medicines.
Mylan said the combined company would have had $15.3 billion in revenue in 2014 and would also be a leader in specialty drugs and nutritional products. It said the combined company would be able to grow even further with additional acquisitions.
Mylan's cash-and-stock offer comes at a premium of 24 per cent to Tuesday's closing price for Perrigo shares. Mylan says it delivered a proposal to Perrigo on Monday. Perrigo confirmed that it received the offer and said its board will discuss the proposal.
Mylan said it wants the combined company led by Mylan executives including Chairman Robert Coury and CEO Heather Bresch.
Shares of Perrigo jumped $30.29, or 18 per cent, to $195 after trading as high as $215.73. Mylan shares peaked at $70.21 and closed up $8.79, or 14.8 per cent, at $68.36.
Mylan NV's bestselling product is the EpiPen Auto Injector, an emergency treatment for allergic reactions made by Pfizer. Mylan reported $1.19 billion in revenue from EpiPen in 2014 and the company says EpiPen is its first product to reach $1 billion in annual sales. However most of the company's business comes from generic drugs, or lower-cost versions of medications, and the company says it is the biggest seller of generic drugs in the U.S. It also makes pharmaceutical ingredients and other products.
Mylan relocated to the Netherlands in February after it paid $5.3 billion to buy a unit of Abbott Laboratories that sells specialty drugs and generic drugs that are marketed under brand names. Mylan had been based in Pennsylvania.
Perrigo Co. moved from Michigan to Ireland in December 2013 after it bought Elan Corp. for $8.6 billion.
The moves slashed both companies' tax bills.
In 2014 a spate of U.S. companies acquired foreign companies and then reincorporated in their target's home country. The move, called a corporate inversion or tax inversion, allowed the companies to move to nations with lower taxes than the U.S. The tactic was criticized by President Obama and others, and in September the U.S. Treasury Department changed some of its rules to make the tactic less attractive. Some companies that had been considering inversions backed away from the move.
Last month Perrigo bought Omega Pharma of Belgium for $4.48 billion including debt. Omega was one of the largest makers of over-the-counter drugs in Europe, and Perrigo said the deal made it one of the five largest OTC product companies in the world.