A one dose at a time, non-pressurized fluid dispensing canister from which the or each dose is dispensed as a result of two surfaces (21, 22) of the canister moving towards one another under the control of the user, wherein the canister incorporates a mechanism which, once a first dose has been dispensed, automatically prevents any further dispensing movement of the surfaces (21, 22) (in the case where the canister is a one-dosage only canister) or (where the canister is a multiple-dosage-dispensing canister) allows such movement only after the two surfaces (21, 22) have first been moved in a direction or directions other than that which alone caused the first dose to be dispensed.