Vyvanse (lisdexamfetamine) makes the penile muscle shrink. why is that? are there long term effects

It does not: There is no such side effect of penile shrinkage with vyvanse (lisdexamfetamine). It's been proved to be safe in large trials. Relax.

See below: There is no evidence to support this concern. However, vyvanse (lisdexamfetamine) is potentially habit forming and can cause growth suppression with long term use. It is a controlled (scheduled) medication with potential for misuse. It is approved for treatment of adhd.