Pfizer plans to kick off an auction process for its consumer healthcare business in November, paving the way for a potential $15 billion-plus sale of the headache pill to lip balm business, sources close to the matter told Reuters.

Several global companies, including GlaxoSmithKline and Reckitt Benckiser, have expressed interest in bidding for the unit, which had sales of about $3.4 billion in 2016.

The prospective sale, which is being led by Centerview Partners, Guggenheim Securities and Morgan Stanley, was first mooted on Oct. 10, when Pfizer said it was considering strategic options for the unit.

But preliminary discussions with interested parties including Reckitt have already taken place, one of the sources said, adding the U.S. drugmaker wants to get the ball rolling before the end of this year.

GSK Chief Executive Emma Walmsley confirmed on Wednesday she would look “carefully” at the business.

Three people familiar with the situation said the British drugmaker had hired Citi to represent it in the auction. GSK declined to comment while Citi was not immediately available.

Other possible bidders could include Procter & Gamble, Sanofi, Johnson & Johnson and Nestle, several sources said.

Pfizer plans to send out financial information about the consumer unit to prospective buyers in around three weeks time, one of the sources said.

The process is expected to heat up early next year as bids come in and a deal could be sealed around the middle of 2018, the source said.

Germany’s Merck KGaA is also looking to divest its consumer health business and has hired JP Morgan to sell the unit, best known for making Seven Seas vitamins.

Some banking and industry sources said Merck could put the divestment on hold since the sale, estimated to be worth around $4.5 billion, risked being eclipsed by the Pfizer auction.

One source said Pfizer believed keen competition would allow it to raise at least $20 billion from the sale of the business, whose well-known brands include painkiller Advil, Centrum multivitamins and lip balm Chapstick.

As aging populations and health-conscious consumers drive demand for self-medication, the consumer health sector has proved a fertile ground for deal-making in recent years.

But the industry remains fragmented and GSK’s Walmsley said she expected more merger activity, with GSK in a strong position to act as a “consolidator”.

Although consumer remedies sold over the counter have lower margins than prescription drugs, they are typically very long-lasting brands with loyal customers.

Pfizer Chief Executive Ian Read said he was considering the sale of consumer healthcare because it was not integral to the core prescription drug business and might be worth more outside the group.

GSK has taken a different view, opting to retain a diverse portfolio in which consumer health offers a hedge against riskier prescription drugs.