In return, the UK’s largest pharmaceuticals firm will buy Novartis’s global vaccines division – excluding those for influenza – for up to $7.05bn.
The two groups also said they would be creating an over-the-counter consumer healthcare business, generating annual sales of about £6.5bn, in which GSK will have a 63.5 per cent controlling stake.
GSK chief executive Sir Andrew Witty said: “Opportunities to build greater scale and combine high quality assets in vaccines and consumer healthcare are scarce.
“With this transaction we will substantially strengthen two of our core businesses and create significant new options to increase value for shareholders.”
Witty said GSK was planning to return £4bn to shareholders, who will be asked to approve the deals at a meeting due to be held before the end of this year.