The Stay singer had hoped to be well enough to perform in Baltimore last night (March 12) but RiRi's rep announced that she would have to pull out after still feeling unwell.
According to the MailOnline, Live Nation stated that fans "are instructed to retain their tickets pending rescheduling show date information" because the 25-year old "is still recovering" from illness.
RiRi is due to perform in Philadelphia on Thursday (March 14) but it is currently unknown whether she will take to the stage.
The Umbrella hitmaker previously expressed her dismay at having to cancel her gig in Boston, tweeting: "Boston this is the hardest thing for me to deal with! I feel like we've been waiting on this day forever, and I'm hurt that I let you down."
"I hate disappointing people that never ever let me down!! I'm so embarrassed about this! Thank you for your prayers and well wishes!"