Johnson & Johnson (J&J) has agreed to buy drugs group Pfizer's consumer products business for $16.6bn (£9.1bn).
Over the counter medicines are in big demand
The deal will cement J&J's position as the world's leading provider of over the counter (OTC) medicines.
Pfizer announced the sale of the unit, which includes brands such as Listerine mouthwash and Sudafed cold treatment, in February after a strategic review.
Following the deal, US-based Pfizer aims to buy back $7bn in ordinary stock in 2006, and another $10m next year.
According to reports, J&J's cash bid trumped other offers from UK companies GlaxoSmithKline and Reckitt Benckiser.
There has been a wave of merger and acquisition activity in the OTC sector recently amid growing demand for the products.
Governments are increasingly promoting self-medication in an effort to cut healthcare costs while companies are looking to the generic market as patents on prescription products run out.
In October, Reckitt Benckiser shelled out £1.93bn ($3.42bn) for Boots' Healthcare division - owner of the Nurofen, Strepsils and Clearasil brands.