The M type potassium channel, whose molecular basis is constituted by KCNQ2-5 homo- or hetero-multimers, plays a key role in regulating neuronal excitability and is modulated by many G protein coupled receptors. Here, we demonstrate that histamine inhibits KCNQ2/Q3 currents in HEK293 cells via phosphatidylinositol 4, 5-bisphosphate (PIP₂) hydrolysis mediated by stimulation of H₁ receptor and PLC. Histamine inhibited KCNQ2/Q3 currents in HEK293 cells co-expressing H₁ receptor and this effect was totally abolished by H1 receptor antagonist mepyramine but not altered by H₂ receptor antagonist cimetidine. The inhibition of KCNQ currents was significantly attenuated by a PLC inhibitor, U-73122, but not affected by depletion of internal Ca²⁺ stores or [Ca²⁺]_i buffering via pipette dialyzing BAPTA. Moreover, histamine also concentration dependently inhibited M current in rat superior cervical ganglion (SCG) neurons by a similar mechanism. The inhibitory effect of histamine on KCNQ2/Q3 currents was entirely reversible but became irreversible when the re-synthesis of PIP₂ was impaired with PI4-kinase inhibitors. Histamine was capable of producing a reversible translocation of the PIP₂ fluorescence probe PLC₁-PH-GFP from membrane to cytosol in HEK293 cells by activation of H₁ receptor and PLC. We concluded that the inhibition of KCNQ/M currents by histamine in HEK293 cells and SCG neurons is due to the consumption of membrane PIP₂ by PLC.