H1N1 symptoms: What to look out for as cases rise in major Indian cities

India’s health ministry has issued an advisory as H1N1 cases continue to rise in several parts of the country, with doctors warning people to pay attention to persistent or worsening flu-like symptoms during the monsoon season.

Delhi has recorded more than 1,777 H1N1 cases so far this year, with 114 new infections recorded on Thursday alone, according to the National Centre for Disease Control. The figure is nearly eight times the 229 cases recorded during the same period last year.

A high number of cases have also been reported in cities such as Mumbai in the west and Bengaluru and Chennai in the south, although the pattern is not uniform across the country. In Bengaluru, paediatricians have reported a rise in influenza A infections among children, with some cases progressing to pneumonia and respiratory distress.

H1N1 , commonly known as swine flu , is a subtype of influenza A . It is a contagious respiratory infection that can cause symptoms ranging from fever and cough to more serious complications such as pneumonia and respiratory failure.

The federal health ministry has urged people to watch for early signs of swine flu and not ignore persistent symptoms, as hospitals prepare for a possible rise in patient numbers.

“Swine flu (H1N1) can show up through symptoms such as fever, cough, sore throat, headache, runny nose, body aches and fatigue...If you experience these symptoms, seek medical advice at your nearest healthcare centre," the ministry said on X.

The Delhi administration has urged residents to follow respiratory hygiene, wear masks in crowded places and seek prompt medical attention should flu symptoms emerge. Health officials have placed 35 hospitals under special surveillance and designated two referral laboratories to handle testing and monitor the situation.

The southern state of Kerala has recorded 1,476 cases of Influenza A and 21 deaths so far this month.

Officials in Karnataka, which has recorded 4,000 cases of H1N1 so far this year, said they will hold a meeting to take stock of the situation. Bengaluru city alone has recorded 2,000 cases, according to reports.

So what are the symptoms to look out for, and when should an apparently ordinary bout of flu become a reason to seek medical help?

A sudden fever is one of the symptoms commonly associated with H1N1, particularly when it appears alongside other flu symptoms. Patients in the capital have recently been presenting with high fever, cough, headache, sore throat, and other respiratory symptoms.

“Many of them have high-grade fever, which has been running for a few days,” Dr Atul Kakar, chairperson of internal medicine at Sir Ganga Ram Hospital, told ANI.

A persistent cough, sore throat, and runny or blocked nose are also common symptoms. Some people may also experience gastrointestinal symptoms, including vomiting and diarrhoea.

Body aches, headache, and pronounced tiredness can accompany H1N1. Dr Sandeep S Reddy, assistant professor and consultant in infectious diseases at Ramaiah Memorial Hospital in Bengaluru, told NDTV that H1N1 can cause severe body aches, headache, and “extreme fatigue or malaise”.