My only experience with having a spinal tap was 20 years ago. It was uncomfortable but only took a few minutes so was easy to tolerate. I did have a major side effect which was a migraine from hell. This migraine lasted 3 days and was only relieved by another procedure at the hospital called a blood patch. Apparently there was a small leak of spinal fluid which caused horrible pain. I’ve heard that you must lay very still after a spinal tap for several hours to avoid this adverse reaction. The hospital got me up 20 minutes after the procedure.