The inhaled bacteria take hold in the lungs and produce toxins. After about 12 hours, symptoms begin to appear. Initial symptoms are generally non-specific, and resemble a common cold. But, after several days of these mild symptoms, the infection begins to rapidly progress. The person may have a high fever and go into shock.
Chest pain occurs and breathing becomes very difficult as the lungs fill with fluids.
It progresses rapidly to a systemic hemorrhagic pathology. The person may briefly improve after 2-4 days, but once this occurs, symptoms become acute, and the person usually dies within 24 hours. Because symptoms of intestinal and inhalation anthrax resemble those of other illnesses, these infections may go undiagnosed until it is too late for antibiotics to be effective. In the case of inhalation anthrax, you could be dead before the diagnosis could be made - especially if you didn't know you'd been exposed. One component of the anthrax toxin has a lethal mode of the action that is not understood at this time.