With increased patient load due to cold wave conditions in the ongoing winter months, doctors are warning of heightened risk of infections (flu, pneumonia, other respiratory illnesses) that may trigger flare-ups of chronic obstructive pulmonary disease, and adversely affect patients with high blood pressure and heart ailments. “Cold weather causes blood vessels to constrict, raising blood pressure and increasing the workload on the heart,’’ Sanjeeva Kumar Gupta, consultant, Department of Cardiology, C.K. Birla Hospital, Delhi, said. Reducing physical activity, higher intake of salty foods, dehydration, and winter illnesses place additional strain on the cardiovascular system, Dr. Gupta added. Cold weather also triggers stress hormones, including adrenaline, which raise blood pressure and heart rate, he cautioned. “During winters, the body’s sodium and potassium levels can fluctuate. Lower fluid intake and dehydration may lead to higher sodium levels. At the same time, changes in diet, use of diuretics, and eating fewer fruits and vegetables can cause potassium imbalance, especially in heart patients,” Dr. Gupta said. Common seasonal respiratory illnesses, alongside stomach viruses such as Norovirus, often exacerbated by …