An inhaler device (901, 1601, 1701) for delivering to a patient at least one active substance, the inhaler device comprising: a controller (913, 1607, 1719) including: a memory (919, 1721) storing one or more scheduled regimens for delivery of the at least one active substance to a user; and a decision module configured to read and/or receive the scheduled regimen from the memory and to make a decision whether delivery should take place; characterized in that: each scheduled regimen defines: a maximal dose of the at least one active substance, and a defined time period within which said maximal dose can be delivered; and in that the controller is configured, based on a decision made by said decision module, to: (a) carry out delivery of an initial low dose of said at least one active substance, said initial low dose determined by said controller; (b) during said defined time period, enable delivery of an additional dose; wherein said initial low dose and said additional dose together do not exceed said maximal dose; and (c) during a second time window following said defined time period, prevent delivery of said at least one active substance delivered in (a) and (b), wherein said at least one active substance comprises THC. a controller (913, 1607, 1719) including: a memory (919, 1721) storing one or more scheduled regimens for delivery of the at least one active substance to a user; and a decision module configured to read and/or receive the scheduled regimen from the memory and to make a decision whether delivery should take place; characterized in that: each scheduled regimen defines: a maximal dose of the at least one active substance, and a defined time period within which said maximal dose can be delivered; a memory (919, 1721) storing one or more scheduled regimens for delivery of the at least one active substance to a user; and a decision module configured to read and/or receive the scheduled regimen from the memory and to make a decision whether delivery should take place; characterized in that: each scheduled regimen defines: a maximal dose of the at least one active substance, and a defined time period within which said maximal dose can be delivered; and in that the controller is configured, based on a decision made by said decision module, to: (a) carry out delivery of an initial low dose of said at least one active substance, said initial low dose determined by said controller; (b) during said defined time period, enable delivery of an additional dose; wherein said initial low dose and said additional dose together do not exceed said maximal dose; and (c) during a second time window following said defined time period, prevent delivery of said at least one active substance delivered in (a) and (b), wherein said at least one active substance comprises THC. (a) carry out delivery of an initial low dose of said at least one active substance, said initial low dose determined by said controller; (b) during said defined time period, enable delivery of an additional dose; wherein said initial low dose and said additional dose together do not exceed said maximal dose; and (c) during a second time window following said defined time period, prevent delivery of said at least one active substance delivered in (a) and (b),