Why does urine turn neon yellow after taking multivitamins?

multivitamins contain minerals. these help in synthesising proteins in your body and when not needed, they will be turned into urea. a lot of urea in water gives the yellow urine :)

The body excretes the B complex vitamins that it does not use, in the urine. These are called water soluble vitamins. This is normal. It will continue. Working out will also contribute to the yellowness of urine, both from dehydration and from muscle breakdown (if you work out hard.) Keep drinking lots of watter during and after workouts.

Your either flushing out trapped waste released from the use of the vitamins, or you're expelling what ever vitamins your body isn't absorbing.

From the vitamins, probably, but check with your doc to be sure.

The stuff is too concentrated and your body instantly filters out what it can't process.

you are taking too many and your body is just getting rid of the excess