I get dizzy spells when i do cardio exercises. i have low blood pressure. how can i prevent this?

Visit a cardiologist: You may have to pay a visit to your primary care doctor and cardiologist to have this evaluated. It might be worthwhile to stop your physical activity until your heart is properly evaluated; it may not be pumping enough blood to your brain during exercise, causing the dizziness. The medications you are one may also be causing the low bp, check with your pcp.