worrying
Worryingly, death from lung cancer is still increasing.
The plants looked worryingly dry and yellow.
More worryingly, there were reports that the disease had spread.

SMART Vocabulary: related words and phrases

Causing anxiety and worry
alarming
alarmingly
bite
catch up with someone
come back to bite someoneidiom
disturb
dread
frighten
frighten someone/something away/off
get/go beyond a jokeidiom
give someone the jimjamsidiom
give someone the jittersidiom
oppressive
rattle
roost
stressful
stressfully
suspenseful
suspensefully
suspensive