BOYS, do you get a stuffy nose, fatigue and the sweats after you've had sex?

No, it's not because your performance was so mind blowing your body couldn't cope - you could actually be allergic to sex.

4 Some men experience flu-like symptoms after they have ejaculated Credit: Getty - Contributor

That's right, post-orgasmic illness syndrome (POIS) is an actual medical condition.

The rare condition causes flu-like symptoms to start immediately after you have, ahem, finished.

It was first documented in 2002 and there have been more than 50 cases recorded worldwide - but it could be even higher if men have not heard of the condition before.

A recent paper from Tulane University School of Medicine in New Orleans noted: "POIS is a rare condition that is under diagnosed and under-reported.

4 Post-orgasmic illness syndrome can cause a stuffy nose and itchy eyes Credit: Getty - Contributor

"Further studies are warranted to investigate the prevalence, pathophysiology, and treatment of this debilitating condition."

Men who suffer from the condition can experience extreme fatigue, weakness, a fever or sweating, mood changes or irritability, problems concentrating, a stuffy nose and itching eyes after getting down and dirty.

They may occur within seconds, minutes or even a few hours after ejaculation.

And they can last as long as two to seven days.

4 The condition can also cause a man's mood to change and become irritable Credit: Getty - Contributor

While the symptoms of the condition are widely recognised, the cause of them is not.

The most commonly held belief is that the flu-like symptoms may be caused by a semen allergy which causes an immediate immune reaction.

A semen allergy is an allergic reaction to a protein found in a man's ejaculate.

It mostly affects women but has been known to affect men too.

Another theory is that some men may have a disorder affecting their endogenous opioid receptors - the most common being endorphins.

Their body is unable to cope with the amount of endogenous opioids being released when they have sex.

As the cause of the condition is not known treating it can prove difficult.

4 Symptoms may occur within seconds, minutes or even a few hours after ejaculation Credit: Getty - Contributor

Some men have been treated with antihistamines, selective serotonin reuptake inhibitors (typically used as antidepressants) and benzodiazepines (a depressant).

One study has used hyposensitisation to treat two men by decreasing their allergy response through exposure - in other words the more they ejaculated the lesser their symptoms became.

The treatment did not cure their symptoms entirely, but they did ease up over time.

Until the exact cause of the condition is known a cure cannot be found.

MORE ON SEX GET IT ONG Get dirty at 30 and frisky at 50 - how to have sizzling sex at every age A-LUST STARS Holly leaves her shoes on & Scarlett likes it in the car - celeb sex secrets SECURE SEX Britain’s first Covid-friendly brothel reopens — but punters must wear masks Exclusive ZAP AND TICKLE Quick laser blast 'can boost a woman's sex drive and increase orgasms' SEX-PLANATION Sexpert reveals ‘disturbing reason women don’t want sex’ & how to change this Revealed CLIP SLIP Surge in 'posh porn' as fans pay THOUSANDS for clips – shunning free videos KISS IT BETTER Simple secret to getting the BEST sex ever - and it works for men & women

Now, it might seem like an allergy you'd be prepared to live with - after all a stuffy nose is worth a toe-curling orgasm, right?

But it can have huge impact on a man's love life and even stop him having sex entirely.

Experts from Tulane University also noted the condition limits sexual encounters, can ruin an man's chance at romance and can even cause them to completely avoid anything that turns them on.

That's certainly not something you'd be willing to give up.

We pay for your stories! Do you have a story for The Sun Online news team? Email us at tips@the-sun.co.uk or call 0207 782 4368.