On Monday, the 21-year-old actress was attending the Chopard Trophy dinner when she fainted. The Teen Spirit star was seated next to her sister, Dakota Fanning, when she collapsed and fell off of her chair, briefly pausing the ceremony and quieting the crowd, Varietyreports.
According to the trade publication, Dakota helped her younger sister to her feet as Colin Firth quickly offered his assistance and Marion Cotillard sat with her hand on her heart nearby. The Fanning sisters were led out of the event by security, reports Variety.
Though it was likely a scary moment for Elle, she later took to Instagram to assure fans she was OK and blamed the incident on both her period and her snug dress.
"Oops, had a fainting spell tonight in my 1950’s Prada prom dress but it’s all good!! #dresstootight #timeofthemonth," she wrote alongside a smiling selfie where she's giving a thumbs up.
The stunning dress that Elle highlighted as the culprit was a nude, vintage, tulle gown by Prada. Elle, who's serving as a juror at this year's festival, finished her elegant look with Chopard jewels and Giuseppe Zanotti heels.
Elle does seem to have fully recovered, as she was spotted leaving her hotel on Tuesday morning looking happy and healthy in a blue-and-white dress and jacket. She was also on hand to see the president of this year's jury, Alejandro Gonzalez, be awarded with the Commander of the Order of Arts and Letters.
When she returns from Cannes, Elle will likely be in full-on promotion mode for her upcoming flick, Maleficent: Mistress of Evil, which she stars in alongside Angelina Jolie and Michelle Pfeiffer. ET's Katie Krause caught up with Elle last month and she gushed about working with the "amazing" cast of the film, and praised Pfeiffer specifically.
"What's so funny [is]... she was in I Am Sam with my sister [when] my sister was really young, so my mom LOVES Michelle Pfeiffer. She was like, 'She was so nice to us!'" Elle said of the 2001 film that starred her older sister. "My sister was super young, just starting out and, like, that made, like, a huge impression on my family."
Maleficent: Mistress of Evil hits theaters on October 8. Watch the video below for more with Elle: