Aussie flu, the H3N2 strain of the influenza A virus, has been recorded in all parts of the UK.
If you become infected, the best thing to do is to stay at home to avoid spreading the virus, said St John Ambulance.
Drink plenty of fluids, and take painkillers to ease some of the symptoms, it said.
The recommendations came after the Aussie flu virus hospitalised about 500 people since October.
“Seasonal flu levels have continued to increase in the last week across the UK, with flu hospitalisations up 50 per cent according to Public Health England figures,” said St John Ambulance Clinical Director, Alan Weir.
“If you have flu, it is important to treat it by avoiding going out in public and spreading the virus further.
“Stay at home, keep yourself hydrated and warm, and take the recommend doses of paracetamol.
“If you have any further concerns, call your GP or 111 for medical advice.”
If flu isn’t treated properly, it could turn into a deadly illness, Weir said.
“Flu should be taken seriously, and by taking proper precautions and looking after yourself, and those around you, should hopefully prevent the virus from turning into something more serious that requires emergency attention.”
Maintaining good hygiene is crucial to limiting the virus’ spread, added Weir.
Washing your hands regularly, or using alcohol gels, could lower your risk of catching the infection, he said.
The best way to prevent infection is to get the flu jab, said St John Ambulance.
The flu is available at most pharmacies, and is free on the NHS to the most at-risk individuals. That includes the elderly, pregnant women, and patients with long-term medical conditions.
“At St John Ambulance we are encouraging all our employees and volunteers to take up the offer of flu vaccination to help protect them, their families and our patients,” said Weir.
Some trivalent and quadrivalent flu vaccines could protect against the Aussie flu strain.