RBC analysts also trimmed the price target to 197p from 210p as shares have rerated more than 35% since the start of the year.
The FTSE 250-listed company will see a tough last quarter combining stock rationalisation and a lumpy infectious diseases division, the analysts said, after the third quarter brought good results thanks to easy comparatives and distributor inventory movements.
RBC's full-year revenue forecast of US$1.8bn is at the bottom of the City consensus range.
ConvaTec has embarked in a transformational strategy to drive greater innovation, customer focus and efficiency which has already yielded some improvements, although margins are expected to dip in 2020 and there are strong competitors out there.
While the company is more ambitious on margins, RBC's analysts reckon it could take a few years for this to translate to higher sustainable earnings growth.
“The company should strengthen materially over the next 2-3 years, but we expect it to be a bumpy ride,” they told clients in a note.
Shares shed 2% to 188.65p on Monday morning.