Popular cereal brand Lucky Charms is undergoing an FDA investigation after cereal-eaters reported being sick after eating the product this past month. The FDA announced their investigation Monday, after receiving 100 official complaints throughout this past year regarding the marshmallow-y cereal.

The investigation also comes after over 4,000 people reported symptoms of an illness after eating the cereal on iwaspoisoned.com, a platform where customers can report that a product or restaurant made them sick. Lucky Charms eaters reported symptoms such as vomiting, bloating, stomach pain, and diarrhea. Customers have also taken to Twitter to share their experiences, tagging the @LuckyCharms account.

“Food safety is our top priority,” General Mills spokeswoman Andrea Williamson said in a statement on Monday. “We encourage consumers to please share any concerns directly with General Mills to ensure they can be appropriately addressed.”

According to the New York Post, the FDA has tapped New York, Michigan, Kansas, and Arkansas health departments to conduct interviews of consumers who are experiencing symptoms. These health departments and a statement from iwaspoisoned.com are urging consumers to keep remaining bags of Lucky Charms for further testing to determine the root of the issue.

One sick Lucky Charms customer reported her sickness to the General Mills owned company on March 31. In response, she received an apology letter and two $7 coupons for any General Mills cereal.

“I’m like, you’ve got to be kidding me,” the customer told the New York Post. “I was irritated and I thought, ‘Honestly if this their response, they are not going to do anything.’”

Despite all the complaints and an FDA investigation, Lucky Charms still stands by a statement that firmly says no link between the cereal and the mysterious illness can be made.

If you or someone you know has gotten sick after eating Lucky Charms, you can post on iwaspoisoned.com, contact your state’s local health department, or share your experience directly with General Mills.