Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. The steroid will help to raise his blood pressure. There are different causes for low blood pressure/hypotension. If he has been tested thoroughly, it is likely that many have been ruled out. Some of the most common reasons are: dehydration, electrolyte disorder, heart failure, side effect of medication, a disorder of the autonomic nervous system, hormonal causes. If blood tests have not revealed any obvious cause, he may need to see a neurologist to see if it is related to the nervous system. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Michelle Gibson James