The 25-year-old singer, who just kicked off her "Diamonds World Tour" tour in Buffalo, New York, is postponing her scheduled concert in Boston due to a bout of laryngitis.
"Unfortunately, following her sold out concert on Friday Rihanna has contracted laryngitis and per doctor's instruction is unable to perform this evening," Live Nation said in a statement obtained by OTRC.com. "Boston fans are instructed to retain their tickets pending rescheduling show date information."
The singer, who is touring in support of her new album Unapologetic, took to her Twitter account to express her disappointment.
"#BOSTON this is the hardest thing for me to deal with!" she Tweeted on March 9. "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! #DWT," she Tweeted.
According to WebMD, laryngitis is an inflammation of the voice box, or larynx, that causes one's voice to become raspy or hoarse. It can be a short-term or long-lasting illness, though the site notes that in most cases it comes on quickly and lasts no more than two weeks.
A spokesperson for Live Nation said that the Baltimore performance on Tuesday, March 12 is expected to move forward as scheduled.
Following her first performance in Buffalo on March 8, the singer Tweeted about her excitement, posting: "#BUFFALO I will never forget how you made me feel tonight!!! Thank you from the bottom of my heart!! #1Love always."
"#DiamondsWorldTour we just getting started!!!" she continued in a seperate Tweet.
The singer's seventh studio album, Unapologetic, was released on November 19. The album's single, "Diamonds," was released on September 27 and quickly reached number one on the US Billboard Hot 100 chart. The album's other singles include "Pour it Up" and "Stay."
The singer Tweeted her excitement about the album's release on Nov. 19, 2012, posting: "Happy WORLDWIDE #UNAPOLOGETIC DAY!!! Thank everybody around the world who's supporting this album. I couldn't be more ecstatic about this."