A head for dispensing liquid as a drip, includes a nozzle onto which a channel for ejecting the liquid leads. Air sucked in from the outside is returned through the channel in the opposite direction. In the nozzle, on the ejection channel, the drip dispensing head of the invention includes a valve functioning as a non-return valve for the circulation of the liquid being ejected. A mobile disc of the valve is produced so as to selectively enable air to pass through the valve when the disc is bearing against the seat thereof in a position for closing the liquid ejection channel. The disc is returned to the position by negative pressure applied upstream, which tends to suck in outside air. The disc is advantageously made of a microporous material, which provides antibacterial filtering of the return air.