Add‐on lamotrigine may leads to higher 50% or greater reduction in seizure frequency compared with placebo (low certainty).
It is very uncertain whether add‐on lamotrigine changes seizure freedom (i.e. total cessation of seizure activity) compared with placebo (very low certainty).
It is very uncertain whether add‐on lamotrigine changes treatment withdrawal compared with placebo (very low certainty).
It is very uncertain whether add‐on lamotrigine changes adverse effects compared with placebo (very low certainty).
Summary of findings: lamotrigine probably leads to higher 50% or greater reduction in seizure frequency (ITT analysis) compared with placebo (moderate certainty).
Summary of findings: lamotrigine showed no clear difference in treatment withdrawal compared with placebo (moderate certainty).
Summary of findings: lamotrigine probably leads to higher ataxia compared with placebo (moderate certainty).
Summary of findings: lamotrigine probably leads to higher dizziness compared with placebo (moderate certainty).
Summary of findings: lamotrigine probably leads to lower fatigue compared with placebo (moderate certainty).
Summary of findings: lamotrigine probably leads to higher nausea compared with placebo (moderate certainty).
Summary of findings: lamotrigine probably leads to higher diplopia compared with placebo (moderate certainty).