The invention relates to a dispenser (1) in particular for liquid to pasty substances, comprising a pumping chamber (14) that has a top pumping chamber wall (9) and a bottom pumping chamber wall (12) in relation to a pumping movement when the dispenser (1) is handled normally, i.e. during a vertical pumping movement; the bottom (12) and top pumping chamber walls (9) extend from laterally inside to laterally outside in relation to a geometrical axis (x) running vertically through the center of the pumping chamber (14). In order to advantageously improve a dispenser of the aforementioned type, the bottom pumping chamber wall (12) is joined to the top pumping chamber wall (9) by designing the two walls as a single piece, or by welding or gluing the two walls together, and when the dispenser is actuated, the bottom pumping chamber wall (12) deforms by folding inward such that an elevated region is formed inside in the lateral direction and a lowered region is formed outside in the lateral direction in order for substance to be dispensed.