Today is my first day on buproprion xl 150 mg. i feel very sad, tired, and out of it. will these side effects subside with time?

Those are symptoms..: Of depression, not the drug the drug is being used to treat those symptoms but takes 4-6 weeks to work. Give it time.

Wellbutrin: I wouldn't assume that these symptoms are necessarily due to the buproprion XL. How much caffeine do you use per day? Significant caffeine intake with wellbutrin can cause a constellation of side effects.