The medication "bupropion" is an antagonist at nicotinic receptors which essentially means that it blocks the receptors where nicotine normally binds.
That makes it a good medicine to cease smoking with as well.
Bupropion also boosts and increases the levels of Serotonin in your brain.
Bupropion or Wellbutrin is normally safe when taken as prescribed by your doctor however sometimes taking Bupropion which is also known as Wellbutrin can cause some side effects such as Seizures or other allergic reactions.
If you do experience any allergic reactions or possible seizures then you should speak with your doctor and let them know about the side effects.
Those side effects after taking Bupropion or Wellbutrin are very rare but do sometimes happen.