In the United States, cannabis use is rising, including among older adults, as is unintentional ingestion. We describe the case of a 94-year-old woman admitted with altered mental status, diarrhea, and hallucinations. She lived with her family, who had noticed recent confusion with weakness, poor oral intake, and loose bowel movements.In the emergency room, her vital signs revealed mild tachycardia and hypotension. She was lethargic, disoriented, confused, and anxious but could answer simple questions. The attending hospitalist administered the Mini-Cog dementia screening and found that the patient was oriented to herself only and was unable to perform word recall tests or complete a clock drawing. The rest of her physical exam was within normal limits for her age.Despite a workup including urine culture, chest X-ray, and computed tomography scan of her head, no organic source for her mental change was found. After five days of admission, a close relative confessed that they had given the patient cannabis oil (marketed as “pure CBD,” i.e., cannabidiol, a nonpsychoactive cannabis derivative widely touted as a remedy for pain, anxiety, and anorexia) in the form of edible brownies to help her with her persistent back pain and poor appetite. We performed a urine drug screen for tetrahydrocannabinol (THC), the psychoactive component of cannabis, which verified cannabis use, as well as exposure to THC. The patient recovered to baseline with supportive care.Currently, there is no governing body or framework for the regulation of cannabis products in the United States. Nonprescription CBD products are not regulated by the US Food and Drug Administration, and these products are not tested for safety, efficacy, or quality. Some producers voluntarily conduct such testing, but there is no regulatory oversight, and consumers may be unaware of the need for testing and/or which testing bodies are credible. Given the rapidly increasing proportion of older adults who are cannabis users, physicians should inquire about outpatient use of cannabis in general and CBD in particular during discussions with patients, even the most elderly.