We have had suicidal ideation and I am in the camp that says always take to seriously. It actually teaches children to not say these things lightheartedly or manipulatively, because not all the attention they get for it is positive! I treated the threat to self harm the way I'd treat a threat to seriously harm or kill any other child of mine - not acceptable, but we also explored what made him say these things and made him go to therapy for anxiety (which he didn't like at first but now does, he likes his therapist and having a chance to vent about his parents and under sibs). He hasn't been for a while because his therapist has been ill and has had scheduling issues, but we would insist on starting up again if he ever were to talk about self harm againl
