Dosages of medication, nutrients and vitamins can be categorized in two basic categories: physiological and pharmacological.
A very low dose that closely approximates what the body would normally produce in a day is considered physiological. A low dose is more supportive to the body’s normal physiology. Cortisone and its related compounds (prednisone) are one example: low dose cortisone can support low functioning adrenals or to help step down from a higher pharmacological dose of prednisone.
The pharmacological dose is typically much higher, such as 5-20X a physiological dose, and is used to manipulate a biochemical process. In the case of steroids, it is to suppress inflammation. Another example includes low, physiological dose 5 mg of lithium from lithium orotate taken once a day to help sensitize neurotransmitter receptors versus a pharmacological dose of 1800 mg of lithium carbonate spread over the day to suppress mania in a bipolar disorder. Generally, physiological doses are available over the counter to use as directed, and pharmacological doses require a prescription.