The "Umbrella" singer was deemed "not capable" of performing and took to Twitter to apologize to fans for having to cancel the Malmo concert last-minute.
"I am sorry to everyone was coming out to my show in Malmo, Sweden," she said in a statement. "It would have been a great time... so much better than being sick with the flu. Ugh! I'm really disappointed I couldn't be there."
Rihanna is scheduled to perform in Stockholm on Tuesday night.