I rarely take vyvanse (lisdexamfetamine). I know it's bad even if I'm not prescribed. However I just took one. Should it be totally out of my urine in 48 hours or less?

Yes. Drink plenty of water.The elimination half-life of lisdexamfetamine typically averaged less than 1 hour, even the amount unconverted to active form is negligible in at most 8 hours. Having said so, it is important , you see your doctor for proper evaluation, diagnosis and care. Taking vyvanse as you indicated tells there may be a problem you need to address. Please talk to your physician.Stay safe.
Likely yes. Vyvanse (lisdexamfetamine) is long acting Dexedrine but most of it is gone in 24 hours and i would think 48 hours it would be gone. Certainly the effects would be gone and likely a drug screen would be negative. If drug screen is the issue, would go further out to be sure.