This article explores the concept of “populist hangover” in the context of Southeast Asia. Its intention is to provide analysts of populism with a series of lessons derived from the Southeast Asian experience. “Populist hangover” is the notion that, though democrats bemoan the arrival of the populist due to the use of popular support to dismantle effective democratic institutions, the departure of the populist does not return the polity to its previous institutional standard. The primary reason for this is the fact that populism’s emergence is both a cause and symptom of social/political exclusion. As a result, the departure of the populist prior to the resolution of this exclusion creates social/political circumstances not conducive to a “return to normal”, democratic or otherwise. The article uses two “populist hangover” cases to support its theoretical argument – the “short hangover” of the Thai military’s political re-emergence and the “long hangover” of the continued hegemonic authoritarian rule of the People’s Action Party in Singapore.