New Delhi, Nov 5 (IANS): There is a nip in the air, and as you welcome the change with light woollens, you also have unwelcome visitors such as flu, cough and fever.

However, it is not just common ailments you should be careful about. 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 here, 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. Therefore those with cardiac problems should be careful around this time," Ahluwalia told IANS.

He also advises diabetics and those with hypertension to take caution.

"Diabetics and those with hypertension and heart ailments should take care to keep their blood pressure under control. Food habits also change during winters, and we often tend to eat food with high calorie and high sugar content. So care should be taken on that front," the doctor said.

"As a precaution, I'll also advise heart patients not to exercise very early in the morning when it is very cold," he added.

Those with breathing problems and asthma may also suffer around this time.

Anuja Chauhan, an internal medicine expert, who runs a clinic here, says these days, she is getting a lot of cases related to acute asthma, pneumonia and viral fever.

"Asthmatic patients are vulnerable to trigger attacks around this time. I advise them and other immune-compromised patients, like cancer patients, to take influenza vaccine every year as winter sets in and pneumococcal vaccine every five years," Chauhan said.

An oddity observed by health experts this year is the persistence of vector-borne diseases such as dengue right up to winters. The number of dengue cases this year in Delhi alone has crossed 1,000.

"Normally such cases (dengue) go down around this time, but surprisingly, we are still getting some cases. There has been no fumigation this time, and contrary to the earlier belief, this year the disease (dengue) has caused more severe symptoms than last year. It could be blamed on water logging," Ahluwalia said.

Flu like symptoms have also become common among children, school teacher Animikha Das said.

"Absenteeism because of cold, cough, viral fever is becoming common these days. We teachers advice parents to make their children wear a protective layer when they send them to school because they are very vulnerable to the change in weather.

"We also monitor the kids' food habits and ask parents to do the same, along with encouraging hygiene practices like washing hands," Das said.

"Remaining hydrated is important to ward off ailments," says physician Ziaur Rahman.

"In winters, we tend to drink less water. So cases of viral fever and cold increase".

Children, who are more vulnerable than others, should be given a high protein diet with lots of fluids, doctors add.

Elderly, pregnant women and diabetics should practice extra care as well.