I take bupropion sr 150mg 2 times every day for my mdd. it works great for me. although, it gives me some side effect that i want to reduce. should a 300mg xl reduce the side effect or 75mg ir 3 times?

Speak to your doctor: Always speak to your doctor when wishing to make changes to your medication dosage for any reason. However, medications which are once daily may cause less side effects than splitting doses as you suggest of regular formula. Also, it's possible that a total lower daily dose could still work well & give less side effects. Again, your doctor should be your GOTO for such questions

Side effects: Any change in buproprion dose, time taken or preparation depends on what side effect bothers you. Review side effects and discuss what to do with prescribing doctor without delay. Be sure he/she knows any other meds you take. I hope this helps.

Which side effects?: In general, reaching a steady state with a 24 hour product reduces the peaks/troughs (highs/lows) of drug levels which may be associated with some side effects. The prescriber and/or your pharmacist is the best source for information on this, and I would strongly suggest that you share your concerns with them.