I’m a physician at The Ohio State University Wexner Medical Center, writing to share a cautionary story about a drug, often seen as harmless, having serious consequences: nitrous oxide, also known as “laughing gas” or “whippets.” A patient from the Athens area came to the hospital with sudden numbness, weakness and trouble walking. It looked like a severe vitamin B12 deficiency affecting the spinal cord, but there was no obvious cause.