@s7r3welty, Welcome to Mayo Clinic Connect! You are attracting quit a group - you with a heart transplant, @chickytina with a double lung transplant, and now me with a liver and kidney transplant! Tacrolimus dosage individual to each patient. It might go up, down, remain at the same level or, in some cases swithched to a different immunosuppressant medication. I have been on Tacrolimus for the entire 16 years since my transplant at Mayo in Rochester. It works well for me and my transplant team keeps an eye on the trough level - and - my routine blood labs to determine if a change is dosage is necessary based on what is best for my transplanted organs.
On a few occassions, my side effects caused me to contact my post transplant nurse about them. And sometimes after consulting with the doctors, she had me lower dose by 0.5 mg of my daily dose. Of course that was always followed with a repeat lab in 2 weeks (sometimes repeat labs).
As for the trough level, it is a range and even it can be adjusted over time.

What kind of side effects are you bothered with? Have you asked your transplant team about managing them whiloe on the current tacrolimus dose? How aften do you see your transplant team or have labs and tacrolimus level measured?