Leslie Mosier was 13 when her first period surprised her during a school trip to Washington, D.C. "I remember thinking, 'This is not what my mom told me about. This is way more intense.'"
Throughout her teens and early 20s, Leslie endured heavy, painful periods and debilitating symptoms that became constant. Despite reporting severe pain, heavy bleeding, leg pain and lower back pain, gastrointestinal and bladder issues, anxiety, and depression, doctors dismissed her symptoms as "bad periods."
In 2017, she first heard about endometriosis. Gynecologists suggested pregnancy, birth control, or surgery as treatment options. Leslie learned to cope, but in November 2018, her family witnessed a particularly severe period over Thanksgiving. "I had a period that my parents were horrified by," she says. "They were like, 'What is happening? You have to do this surgery, whatever it is, and see if you have endometriosis.'"
With their support, Leslie had her first surgery in 2018. Though not performed by an excision specialist, her doctor confirmed her stage IV endometriosis diagnosis. She had a second excision surgery four years later in 2022.
With over 1 in 10 women and people born with a uterus affected, Leslie sought to find others online who understood what she was going through. Already a social media personality through her celebrity dog, Doug the Pug, she had built a career sharing her life. Doug amassed over 18 million followers across his social media accounts, and Leslie chronicled her own life for over 1 million people. Sharing her endometriosis diagnosis felt natural. "I posted about it on Instagram saying, 'Hey, I have endometriosis,' and I realized how much of a community there was," she says.
After her first excision surgery, Leslie channeled her pain into music. Working with her husband Rob Chianelli, a drummer and music producer, she wrote and recorded a song chronicling her endometriosis journey. She released hHer song, “Get Better,” was released during Endometriosis Awareness Month in March 2019, and the reception from and was well received by the endometriosis community was extremely positive. She ended up being contacted by the Endometriosis Foundation of America and invited to their annual gala, Blossom Ball, where her song was played. “Being in a giant room full of people who heard my song and were sharing their stories with me, I realized there is a real opportunity here for me to be able to use my voice on my platform, it's through music, art, or working behind the scenes with EndoFound,” she says.
Since sharing her journey, Leslie has made meaningful friendships with many patients. Today, along with social media strategist Claire Barthelmy, she runs the Endometriosis Foundation of America’s social media platforms, prioritizing raising awareness about the condition and helping other patients feel seen and heard. "It felt like this was a part of my calling to be a voice for people who may not feel comfortable with social media," she says. Her work at EndoFound has had an incredible impact; in less than two years, she has helped grow the foundation’s Instagram followers by over 70,000.
Bringing Endometriosis to Cannes Lions
In June 2026, Leslie shared her endometriosis story on stage at Cannes Lions in France. She was invited to sit on a panel that her manager organized discussing how creators build durable and sustainable sources of income. Despite this honor being such an important moment for her career, her endometriosis flared up before and during the trip. She started spotting the week before, and her period started two hours before her overnight flight. "My business manager saw me in absolute agony," she says. "It was a very rough first night."
In France, the record-breaking heat only intensified her symptoms: "Heat makes it so much worse. I notice so much more bloating, water retention, and joint pain. Everything just hurts so much more."
Leslie relied on pain medication, heating patches, and a portable fan to manage her symptoms. On the panel, she highlighted healthcare challenges for creators and influencers. "There is such a lack of healthcare for creators, and it's something that I've come up against so often," she says. "It's been a huge barrier, and we're constantly fighting this struggle with insurance companies."
After the panel, Leslie experienced both the excitement of a career milestone and the defeat of yet another endometriosis flare. "The juxtaposition of life is so crazy where in the morning, you can be having this career high and at night, you can be sobbing in agony and feeling so far from home," she says.
Leslie posted a vulnerable video from her hotel bathroom, showing her flare at Cannes Lions. The post garnered nearly 14,000 likes, hundreds of comments, and over 220,000 views. "I wanted to show the realities of living with endometriosis and traveling, because everything looks picture-perfect on my Instagram, and today it was. But this is what I am being punished with," she says.
Leslie plans to continue sharing her endometriosis journey, including her upcoming third excision surgery, to help others feel less alone. "Always speak from your heart and just know that whether you have five or 5 million followers, sharing your story does more than you think," she says. "We are all stronger in numbers, and I truly believe that change is going to come because of the bravery of so many people sharing their story."
