"Based on Rihanna's examination, after Grammy rehearsal today, Rihanna's doctor put her on vocal rest for 48-hours because she was at risk of hemorrhaging her vocal chords," her rep said in a statement to ABC News.
"The antibiotics she has been on for 3-days did not kill the infection adequately therefore she cannot perform safely."
The 27-year-old Grammy winner had just dropped her new album "Anti" in January and was supposed to perform new single "Kiss It Better."
According to Billboard, Rihanna did arrive in Los Angeles at the Staples Center to rehearse, but never walked the red carpet before the show. She was also expected to start her world tour for "Anti" at the end of February.
She also tweeted how sorry she was she couldn't be there.
#NAVY so sorry I couldn't be there ..... Thanks Grammys and CBS for your support tonight.— Rihanna (@rihanna) February 16, 2016