The profitable retailer of over-the-counter drugs could be valued at around 250 million euros (228.60 million pounds), including debt, in a potential deal, the people said.
Non-binding offers for the unit are due shortly, with mostly private equity groups expected to show interest in the start-up with some 100 employees, they said.
ProSieben said it announced in March 2020 it would examine all existing investments to see whether there are clear synergies with its core business, adding that it would assess in each case whether it is the best owner for individual companies.
ProSieben, under new management, is looking to raise money from asset sales after the reign of former CEO Max Conze ended amid boardroom acrimony earlier this year and the COVID-19 pandemic slashed advertising revenues at its core commercial television business by 40%.
New CEO Rainer Beaujean is also having to contend with persistent takeover speculation after Italy's Mediaset amassed a 24.2% stake, while Czech investor Daniel Kretinsky and private equity firm KKR have also built shareholdings.
Prosieben is also launching a sales process for online fashion retailer Stylight, which has roughly 30 million euros in sales, the people said, adding investment bank Macquarie was organising the auctions.
Separately, ProSieben is exploring the possible sale of beauty products retailer Flaconi, which competes with larger peers Douglas, one of the people said.
ProSieben bought Windstar Medical in 2016 through its technology subsidiary NuCom.
Windstar Medical sells non-prescription healthcare products and has its own brands including SOS, GreenDoc and Vitalia and, according to ProSieben's 2019 annual report, saw "significant growth".
($1 = 0.8543 euros)
By Arno Schuetze and Klaus Lauer