People are posting pictures of their sunburns after using Jessica Alba's 'Honest' sunscreen

Jessica Alba's billion dollar empire has encountered an honest new problem.

Honest, the lifestyle product company co-founded by the 34-year-old actress is under fire after some customers say its sunscreen didn't work as advertised.

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Upset customers have taken to posting pictures of their sunburns to social media.

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Some customers also claim that The Honest Company is not responsive to their concerns.

In a statement to ET, Honest maintains that its sunscreen has been tested, and is safe, when used correctly.

"The Honest Company is committed to providing safe and effective products, and we take all consumer feedback very seriously," it said. "Our Sunscreen Lotion was tested, by an independent 3rd party, against the protocols prescribed by the U.S. Food & Drug Administration's (FDA) monograph for over-the-counter sunscreen products. The results showed that our product is effective and safe for use as an 80 minute water-resistant (FDA's highest rating), SPF 30 sunscreen lotion in accordance with FDA regulations when used as directed (Shake Well. Apply liberally and evenly 15 minutes before sun exposure. Reapply after 80 minutes of swimming or sweating, immediately after towel drying and at least every 2 hours)."

The company also notes that the number of complaints are small compared to the number of units sold.

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"The number of complaints received on our own website about our Sunscreen Lotion constitute less than one half of one percent of all units actually sold at honest.com. We stand behind the safety and efficacy of this product," the statement added.

The sunscreens formula was changed at some point, reducing zinc oxide -- the active ingredient in many sunscreens -- to 9.3 percent from 20 percent, reported NBC 5 in Chicago.

"The Honest Company has been transparent about the amount of zinc since the new formula came out in early 2015 as seen on the website and the new formula's packaging," the company said in a statement to Today.

In December of last year, Alba told ET that she hoped The Honest Company, valued at over $1 billion, would one day be an opportunity for her daughters, 7-year-old Honor and 3-year-old Haven.

"I really am building The Honest Company for them," she told ET's Nischelle Turner. "I'm really hoping that ... The Honest Company is some place that they would like to work later, when they're older."

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ET reached out to Alba's reps for comment on the sunscreen controversy.