Lost his sense of smell in a car accident -- and his family wants to know if stem cells can bring it back

“Doctor Roach” responded to a reader asking whether stem cells could restore smell and taste in her 82-year-old husband after a 2024 car accident. He suffered a spinal compression fracture and head trauma, and since then has had no sense of smell or taste. The doctor said smell loss often causes a perceived taste loss, since aroma is crucial to tasting; people with temporary smell loss from sinus infections may describe food as bland. He noted olfactory training—using the scented items provided by physicians—can be effective, especially for post–COVID smell problems. However, loss of smell after head trauma has a worse prognosis. While mouse stem-cell studies exist, human clinical trials weren’t found, and platelet-rich plasma trials have shown limited results so far.