Viruses are spread from person to person through the exchange of bodily fluids, according to a pharmacist.
A simple kiss could be enough to give you a cold or a sore throat, they added.
The pharmacist’s comments came after reports the Southern Hemisphere was battling a lot more flu viruses this year.
The influenza strains, including the deadly Aussie flu, could impact the UK, it was revealed.
Pharmacist, and menthol confectionery expert at Jakemans, Marvin Munzu told Express.co.uk: “As the darker nights draw in, we tend to spend our evenings tucked up at home with our loved ones, avoiding the cold in a bid to dodge winter bugs and illnesses.
“Although viruses thrive in cold weather, you have a higher chance of picking up seasonal viruses and bacteria indoors – especially if someone at home has a sore throat, cold or flu.
“Not only can viruses be spread by sneezing, they are usually contained in saliva and can spread from one person to another through exchange of bodily fluids such as kissing.”
The best way to protect yourself against flu was to not be intimate with your partner, if they aren’t feeling well, Munzu added.
“To avoid catching a sore throat this winter, it’s best to refrain from kissing your partner if he or she is under the weather – no matter how much you would love to kiss them better.
“Most sore throats are self-limiting, and do not require a doctor. So for effective sore throat relief, try sucking on some delicious Jakemans menthol confectionery.”
The Australian flu is a particularly contagious flu strain, experts warned.
Public Health England (PHE) advised the public to get the flu jab, which is available to at-risk patients for free, including the over-65s and those with a weakened immune system.
Ahead of any Aussie flu reaching the UK, PHE’s Medical Director, Paul Cosford, said: “The strains of flu circulating in Australia this past winter have led to a significant increase in cases, but it’s too early to know which will be the dominant strains of flu to circulate in England.
“Each year the World Health Organization reviews the circulating strains of flu and recommends which flu strains should go in the flu vaccine.
“It’s really important that as many eligible people as possible get their jab which is the best way to protect everyone from flu.”
The health watchdog also recommended that the public takes a 10mg vitamin D supplement everyday. It was revealed this week that vitamin D could be just as protected against flu as having the flu vaccine.