Read Aadil Palkhivala's reply:
Students with low blood pressure need two things as far as asana is concerned.
First, what to avoid: quick changes of pressure in the head. This means that movements such as coming up from Uttanasana (Standing Forward Bend) into Tadasana (Mountain Pose), from Sirsasana (Headstand) into Balasana (Child's Pose), getting up from supine poses into seated ones, getting up from sitting poses into standing poses, rising from front-bending poses into Dandasana (Staff Pose)—all these must be done slowly and on an inhalation, or else the student may become dizzy and even feel faint. Of course, the lower the blood pressure, the slower and more careful the student has to be.
Second, what to do: poses that increase pressure in the head, and those that stimulate the kidneys. Thus all inversions are beneficial, provided you take the precautions above. All backbends stimulate the kidneys, as well as all twists—especially twists with the forearm on the kidneys, such as Bharadvajasana (Bharadvaja's Twist) and Marichyasana I (Pose Dedicated to the Sage Marichi, I). An excellent series for increasing blood pressure is the Tibetan series (often called the Tibetan Rites), which use the breathing of compression. Do not change the breathing to make it yogic breathing, since that will not increase pressure in the kidneys and the endocrine system. (Note: The opposite is true for students with high blood pressure, for whom the Tibetan series is done only by using yogic breathing.)
Recognized as one of the world's top yoga teachers, Aadil Palkhivala began studying yoga at the age of seven with B.K.S. Iyengar and was introduced to Sri Aurobindo's yoga three years later. He received the Advanced Yoga Teacher's Certificate at the age of 22 and is the founder-director of internationally-renowned Yoga Centers™ in Bellevue, Washington. Aadil is the director of the College of Purna Yoga, a 1,700 hour Washington-state licensed and certified teacher training program. He is also a federally certified naturopath, a certified <a href="/health/ayurveda">Ayurvedic health science practitioner, a clinical hypnotherapist, a certified shiatsu and Swedish bodywork therapist, a lawyer, and an internationally sponsored public speaker on the mind-body-energy connection.