How long should I wait to take Imitrex after taking Lexapro?

Hi, honey!
The problem is that certain amounts of Lexapro stay in your system for several days. There is a slight risk of a condition called serotonin syndrome which is rare but can be serious without early treatment in a few cases. Just be aware of the early symptoms and report anything unusual to your doctor.
https://www.drugs.com/cg/serotonin-syndrome.html
Ask your doctor but you can probably take the Imitrex anytime. They likely have determined that the benefit to you is greater than the potential risk.