My Brother Wanted To Give A Blood Donation Today They

my brother wanted to give a blood donation today they would not let him said his bp was to low it was 103/36 is this a concern that I should get him to a doctor he takes the following meds : Abilify 15 mg :Lithium Carbonate 300 mg 3x day: Wellbutrin XL 150 mg and Fluoxetine 20 mg. could this be why his bp is low he is very active but when he is in the house all he does is sleep he is 20 years old been diagnosed ADHD, BI-POLAR, PTSD the reason for these meds THANK YOU FOR YOUR ANSWER