Millions of Brits have been warned that the icy conditions sweeping the country could have more than just an aesthetic impact "downstairs".

The weather-related affliction known as "winter penis", is used to refer to how male genitals shrink in the colder months as a result of blood flow to the area being restricted.

The phenomenon can see penises shrink by up to half in size, but the reduced blood flow to the area that occurs can also make it more difficult to maintain an erection, particularly impacting people suffering from erectile dysfunction (ED), medics warn.

Dr Donald Grant, a GP and senior clinical advisor at The Independent Pharmacy, says "winter penis" occurs because when the mercury drops, "the body prioritises other, more essential areas to maintain warmth - such as vital organs found in our core.

"The testicles shrink so they remain as close to the body as possible to stay warm," he added.

For most, winter penis happens only occasionally and doesn't last long, but men who already suffer from ED "could find their condition more difficult to manage, when weather begins to deteriorate,' Dr Grant explained.

“While cold weather and winter penis can not directly cause erectile dysfunction (ED), they can still impact men’s ability to achieve and maintain erections, impacting sex life and confidence," he continued.

Dr Grant said when blood flow is restricted by cold weather, it can "dramatically" impact "erection quality as the body prioritises more important sections of the body.

"Therefore, men who already suffer from ED could find their condition more difficult to manage, when weather begins to deteriorate," he added.

Dr Grant noted that ED can "stem from psychological effects, with not being able to get aroused or in the correct mood a common theme among sufferers.

"Cold weather doesn’t help this at all, leading to cold stress or general discomfort, seasonal affectiveness disorder could also play a part, leading to a decrease in libido."

There here are a range of treatments available for those suffering from ED, Dr Grant says, and winter penis is natural and "very rarely a cause for concern".

"It will resolve on its own without any needed treatment or medical attention and will occur to most men throughout the winter season," he added.

However, Dr Grant recommended that anyone experiencing problems associated with blood flow a long-term change in size or shape of genitals "seek more tailored advice from their GP, who can advise on lifestyle habits, treatments and potential causes".

ED, also known as impotence, is usually caused by stress, tiredness or drinking too much alcohol, and is nothing to worry about, according to the NHS website.

It can also result as a side effect of some medicines. If erectile dysfunction happens often, it could also be caused by conditions including high blood pressure or high cholesterol, diabetes, depression or anxiety, hormone problems.

The health service recommends seeing a GP if it keeps happening.