Doctors have warned against 'prolonged vigorous' bedroom antics after treating a patient with a potentially deadly injury to his genitals.
The 53-year-old man suffered inflammation in the main vein that runs along the shaft of the penis, which can lead to life-threatening blood clots.
He had a Viagra-fueled rough sex session the previous night which had led to extreme swelling on the undercarriage of his phallus.
The skin was warm to the touch and 'tender', with a visible bulge as a result of a build-up of fluid.
The man, who has not been named, was treated with anti-inflammatory drugs and made a full recovery within a few weeks - but his doctors are using his case as a warning.
They say doctors should be wary about prescribing Viagra to patients who are likely to have vigorous sex or who have pre-existing damage to their genitals from intercourse.
Revealing the case in a medial report, they add people should be aware of the 'potential risks' of the erectile dysfunction drug.
Around 8,000 men in the US suffer a penis injury in the US per year with penile fractures and trauma from penetration the most common.
Doctors have warned against 'prolonged vigorous' bedroom antics after treating a patient with a potentially deadly injury to his genitals (file image)
The latest patient was treated in Turkey and his case was revealed in the journal Radiology Case Reports.
The man claimed he had taken Viagra for his erectile dysfunction before having 'prolonged vigorous' sex with his partner.
He was officially diagnosed with penile Mondor disease, when the veins become inflamed and cause swelling.
The lesion usually appears within hours of prolonged sexual intercourse and causes immune cells to rush to the location of the injury.
This inflammation causes the vein to swell and become sore. It also makes blood more likely to clot.
The man was diagnosed after an ultrasound and given a course of blood thinners, anti-inflammatories and told to abstain from sex for a few weeks.
Writing in the report, his doctors said: 'While penile Mondor disease is not typically life-threatening, it can significantly impact a patient's quality of life.
'Therefore, clinicians should remain vigilant about the potential risks of prolonged sildenafil use.
'They should consider additional predisposing factors, such as vascular injury from sexual activity, in the management and prevention of this condition.'