redness at injection site tirzepatide & Zepbound Rash and Injection-Site Reactions: Causes, Treatment, and Prevention Injection Site Reaction : r/tirzepatidecompound
Description
Laura Williams provide the details in a GREAT article

The activation of Vyvanse in the body makes it more difficult to abuse, though it is still possible

I am not making any claims to the safety or effectiveness of any drug product(s)

Both drugs activate overlapping GLP-1 pathways, so combining them amplifies side effects without proven additional benefit
The problem is that this system can become dysregulated

doi: 10.2337/db09-9028
