Many studies have emphasized the role of natural resources in the onset and duration of armed conflict. Due to its characteristics, narcotics are considered to be one of the most influential resources. However, the dynamics of how this particular commodity is linked to conflict is still not well understood. Most scholars have focused on the revenue aspects of narcotics and only few have mentioned the micro-level aspect, i.e. the effect of drugs intake and alcohol consumption on combatant's behavior during the conflict. With the help of a dataset based on 224 interviews held with former combatants in the Democratic Republic of the Congo, we examined this latter dynamic. Our analyses show, after controlling for armed group-level and individual-level variables, that drug intake and alcohol consumption boost the amount of perpetrated violent actions by combatants.