My blood pressure is always abnormally low. I know that’s usually healthy, but sometimes it makes me feel dizzy. What should I do about that? —C.L., Malibu, Calif. 

Probably nothing. Some people naturally have readings below what’s conventionally considered "normal," with systolic pressure, the higher number, as low as 85 to 100 millimeters of mercury. Such low blood pressure, if not caused by disease or medication, is actually normal for those individuals; in fact, they tend to live longer than other people do. They may experience occasional dizziness, especially after they change position quickly. But that’s generally the only symptom, so there’s typically no need for treatment. If the dizziness becomes frequent or severe or leads to fainting, try boosting your blood pressure somewhat by wearing pressure stockings on your legs or possibly by consuming more salt in your diet. If those steps fail, you may need medication to raise the pressure by forcing your body to retain more salt.