Yoga is generally considered to be safe in healthy individuals when practiced appropriately, and it has been well tolerated in studies with few side effects. Yoga can be adapted for a wide variety of specific needs, including for people who are bed-ridden or wheelchair-bound. Yoga techniques are believed to be safe during pregnancy and breastfeeding when practiced under the guidance of expert instruction (the popular Lamaze techniques are based on yogic breathing). However, poses that put pressure on the uterus, such as abdominal twists, should be avoided in pregnancy.
Some positions and postures should not be used by people with certain conditions or illnesses. Therapy should be exercised under well-qualified guidance. Patients with disc disease of the spine, fragile or atherosclerotic neck arteries, risk for blood clots, extremely high or low blood pressure, glaucoma, detachment of the retina, ear problems, severe osteoporosis, or cervical spondylitis should avoid some inverted poses. Certain yoga breathing techniques should be avoided in people with heart or lung disease. Some experts advise caution in people with a history of psychotic disorders (such as schizophrenia), due to a risk of worsening symptoms, although this has not been clearly shown in studies. People with medical conditions should speak with a qualified healthcare professional before starting yoga.
Rare side effects are described in case reports, including physical damage (due to prolonged postures), nerve or vertebral disc damage (due to prolonged postures, sometimes involving the legs), eye damage and blurred vision including worsening of glaucoma (due to increased eye pressure with headstands), and stroke/blood vessel blockage (due to decreased blood flow to the brain or other body parts from postures). Lung and breathing problems have been reported possibly resulting in death.
This information is based on a professional level monograph edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com): Dawn Costa, BA, BS (Natural Standard Research Collaboration); Cynthia Dacey, PharmD (Natural Standard Research Collaboration); Nicole Giese, MS (Natural Standard Research Collaboration); Carolyn Williams Orlando, MA (Natural Standard Research Collaboration); Shaina Tanguay-Colucci, BS (Natural Standard Research Collaboration); Catherine Ulbricht, PharmD, MBA[c] (Massachusetts General Hospital); Minney Varghese, BS (Northeastern University); Wendy Weissner, BA (Natural Standard Research Collaboration); Jen Woods, BS (Natural Standard Research Collaboration).