An inhaler for powdered medicament in capsules has a swirling chamber which can be opened to allow access of a closed capsule into the swirling chamber for operation of capsule-opening means in the swirling chamber. Access to the swirling chamber is gained by a pivoting cover member (22) which is provided with interlock means associated with the capsule-opening means to ensure that the capsule opening means cannot be operated while the cover member is in its open position to allow access of the user's fingers to the region (28) of the swirling chamber (26,28) where the capsule-opening pins (30) could damage the user's finger.