L'Oreal, one of the world's largest cosmetics companies, missed estimates for its second-quarter sales growth citing weakness in U.S. demand.

Chairman and Chief Executive Jean-Paul Agon told CNBC Wednesday that the trading environment was "never steady" in the U.S. and that the makeup industry was vulnerable to the country's economic cycles.

"We started from scratch in the U.S. 50 years ago, we are now number one and it has never been a walk in the park. So some years are better than others. This year is a bit tough, we acknowledge that," he told CNBC's Julianna Tatelbaum.

Consumer analysts have highlighted a boom in the U.S. makeup market in the last five years, with many celebrities launching their own successful brands, such as singer Rihanna's Fenty Beauty collection or Kylie Jenner's Kylie Cosmetics.

A raft of Instagram celebrities and bloggers promoting cosmetics and makeup tutorials has also led to a generation of millennials who are more confident with makeup products, styles and application than their parents' generation.

But Agon said Wednesday that "the makeup market has really slowed down in the U.S.," which suggests that recent boom may have peaked.