Federal regulators Tuesday threatened cannabis giant Curaleaf with possible legal action for allegedly making unsubstantiated medical claims about the cannabidiol, or CBD, products on its website and on social media.

In a public letter, the U.S. Food and Drug Administration gave Massachusetts-based Curaleaf about two weeks to explain what it has done to correct alleged violations, including website claims that CBD has “properties that counteract the growth of spread of cancer” and is “linked to the effective treatment of Alzheimer’s disease.”