Addition means continued use in spite of negative consequences.  In this sense Benadryl addiction is not known to be a common problem.  Since it can cause weird reactions at high doses I guess that is possible.  People who abuse downers are usually trying to be somewhat emotionally "numb" - so that’s a possibility.

Many people confuse physical dependence with addiction.  This results from taking something long enough or in high enough doses that  you become physiologically adapted to it - then if you just stop it you can have withdrawal symptoms.  In the latter case you just need to taper it slowly - it could take a few weeks, depending on how long you have taken it regularly.

The other issue would be what were you taking it for?  Is there a condition that needs to be treated?

Vyvanse is a new delivery system for a medication we have used for 70 years.  Extra precaution needs to be taken with CV issues like Mitral Valve Prolapse.  I’m not aware of a specific study with MVP, but a study was done at Harvard of patients with ADHD and high blood pressure.  The blood pressure was gotten under control first - then the patients were treated for ADHD and tolerated stimulants as well as patients with normal blood pressure.

Starting low and going slow would be essential with decreased dose or stopping if you have any side-effects that could be related to the drug, such as palpitations, dizziness, etc.