[en] We investigate the bounds on axionlike states from flavor-changing neutral current b→s decays, assuming the axion couples to the standard model through mixing with the Higgs sector. Such GeV-scale axions have received renewed attention in connection with observed cosmic ray excesses. We find that existing B→Kl⁺l^- data impose stringent bounds on the axion decay constant in the multi-TeV range, relevant for constraining the 'axion portal' model of dark matter. Such bounds also constrain light Higgs scenarios in the next-to-minimal supersymmetric standard model. These bounds can be improved by dedicated searches in B-factory data and at LHCb.