Bupropion plus varenicline showed no clear difference in smoking cessation (at least six months of compared with varenicline alone (moderate certainty).
Bupropion plus varenicline showed no clear difference in serious adverse events compared with varenicline alone (low certainty).
Bupropion plus varenicline showed no clear difference in dropouts due to treatment compared with varenicline alone (low certainty).
Varenicline leads to higher smoking abstinence at longest compared with bupropion (high certainty).
Varenicline showed no clear difference in SAEs compared with bupropion (low certainty).
Varenicline showed no clear difference in neuropsychiatric SAEs compared with bupropion (low certainty).
Varenicline showed no clear difference in cardiac SAEs compared with bupropion (low certainty).