Céline Dion consumed up to 90 milligrams of Valium amid health challenges: “Could have been fatal”

After enduring undiagnosed symptoms of stiff-person syndrome for 17 years, Céline Dion reflects on her health journey with gratitude.

In PEOPLE's latest cover story, the 56-year-old music icon shares her experience with the progressive symptoms that emerged in the mid-2000s, including muscle spasms, breathing difficulties affecting her singing, and severe "crisis" episodes where her entire body would lock up, causing intense pain.

Dion recounts the onset of her symptoms nearly two decades ago while on tour in Germany. "I had breakfast, and I suddenly started to feel a spasm. My vocal exercise made it worse," she recalls. 

Dion offers fans a poignant glimpse into her battle with SPS in her upcoming documentary, ‘I Am: Céline Dion’, which will be available for streaming globally on Prime Video starting June 25.

Despite trying various remedies such as steam showers and over-the-counter medications, and consulting with ear, nose, and throat specialists and ophthalmologists, none provided relief for Dion.

As her symptoms worsened, the ‘I’m Alive’ singer, known for her impeccable vocals and captivating stage presence, was advised to try prescription medications, including muscle relaxers like Valium.

"We started with two milligrams to see if it would help, and then 2.5, and then 3, and 15 and 50," Dion explains. She reveals that the medication's effects diminished rapidly, leading her to take an alarming 90 milligrams of Valium at one point in order to get through a performance.

"It could have been fatal. I did not question the level because I don't know medicine. I thought it was going to be okay. It worked for a few days, for a few weeks, and then it doesn't work anymore," she says. "I did not understand that I could have gone to bed and stopped breathing. And you learn — you learn through your mistakes."

Dion says she is "very, very happy and fortunate" she's able to share her learnings with others today.