It is not just common ailments such as flu cough and fever that you should be careful about this winter. Doctors say cardiac problems and other serious health complications also see a rise in this changing weather. Vikas Ahluwalia an internal medicine consultant at Max Super Speciality Hospital in New Delhi says those with cardiac problems should be extra careful as winter sets in. ‘As winter sets in we see a rising number of cases of heart attack and other coronary artery diseases and this is a trend every year. This is because viscosity of blood increases when temperatures drop.