A man was left with a circular-shaped mark in his mouth that doctors claim was caused by performing fellatio.

Dentists in Mexico stumbled across the 47-year-old's red lesion in the roof of his mouth during a routine check-up.

Baffled as to what it could be, they quizzed the patient, who hasn't been identified and wasn't aware he had the mark.

They eventually agreed the red skin, known medically as a erythema, was likely to have been caused by performing oral sex.

Dentists in Mexico stumbled across the 47-year-old's red lesion in the roof of his mouth during a routine check-up

The medics, from near Monterrey in the state of Nuevo Leon, on the border with the US, published their tale in a prestigious medical journal.

Writing in the BMJ Case Reports, they claimed more dentists should be aware that fellatio can lead to oral lesions.

Explaining how it happened, they said: 'The contact of the palate with the penile glands may cause a haematoma due to blunt trauma.'

The team, led by Dr Luis Alberto Mendez, added that the dilation of the blood vessels in the mouth caused by sucking also helped it to form.

They told the patient the lesion would resolve on its own. A decrease in the redness of it was noticed after just one week

HOW CAN FELLATIO CAUSE LESIONS IN THE MOUTH? Fellatio is defined as the stimulation of a man’s penis by a partner’s mouth, although it can be undertaken by adults of any gender. This practice has become very popular, particularly among young people, because it is considered safer than regular sex. The contact of the palate with the penile glands may cause a haematoma due to blunt trauma and dilatation of the blood vessels because of the negative pressure created while sucking. Advertisement

The man presented to the School of Dentistry at the Universidad de Montemorelos after he noticed a filling had broken.

The dentists then examined the rest of his mouth and discovered a 'circular-shaped erythematous lesion'.

However, it had not caused any symptoms and therefore the man was unaware of the lesion.

Upon questioning, the man admitted to being sexually active with men and having recently used marijuana and cocaine.

He also revealed that he regularly performs oral sex, with his last instance being just three days before his dental visit.

The dentists wrote: 'With this information, we concluded the erythema on the soft palate was associated with the practice of oral sex.'

They told the patient the lesion would resolve on its own. A decrease in the redness of it was noticed after just one week.

If it didn't clear-up, dentists may have been required to perform a biopsy as lesions can also form as a result of oral tumours.

Writing in the journal, Dr Mendez and colleagues added that other causes of such lesions can include playing a wind instrument.