n this talk I will present some recent results on instabilities of anti-de Sitter flux compactifications in effective field theories arising from non-supersymmetric string models, namely the USp(32) and U(32) orientifold models and the SO(16) x SO(16) heterotic string. We focus on non-perturbative instabilities, framing the vacua in terms of brane stacks, analyzing their back-reacted geometry and reproducing AdS its near-horizon limit. Then, we describe the instabilities as branes separating from the stack, computing the associated decay rate matching a probe brane computation with the semi-classical Coleman-de Luccia result. We conclude briefly discussing possible implications regarding the fate of unstable vacua in string theory beyond the semi-classical limit, connecting this scenario to holographic renormalization group flows and to a "de Sitter on a brane" construction that was outlined in the recent literature.