There were no associations between any adverse events and CYP2D6 phenotypes (rash: OR, 1.77; 95% CI, 0.54–6.41; *p = 0.35, diarrhea: OR, 1.08; 95% CI, 0.21–7.43; *p = 0.93, liver dysfunction: OR, 0.93; 95% CI, 0.20–5.07; *p = 0.93). Here, CYP2D6 is linked to Decreased liver function.