Pain - Can you have withdrawal symptoms from a reduction in a 600mg bupropion to a 400mg dosage? If?

First let me say that the maximum for bupropion is 450mgs so it is a good thing to have reduce from 600mgs. Secondly, yes you could be experiencing some side effects from reducing the dosage. It will level out over the next week or so. Symptoms may include headache, diarrhea, "brain zap" sensations and general malaise. The risk of seizure increases with the higher you go in dosage of bupropion so that fact that you are reducing is a positive. If you reduce slowly over time, you will experience less in the way of withdrawals if any.