A man claims he was hospitalised and feared he would lose his penis after being bitten by a black widow spider.
Fergus Farrelly, 26, says he woke up one morning and spotted a painful marble-sized lump on his private parts - which kept growing larger and larger.
Baffled and in pain, the construction worker was rushed to hospital when the lump began to go a dark purple colour.
It swelled to the size of a golf ball and Fergus, from Shercock in County Cavan, Ireland, was hospitalised for four days
He claims he was prescribed a cocktail of drugs after doctors spotted venom of a black widow spider in his blood tests.
However, he is now getting back on his feet - although he continues to sport a two-inch scar on his penis.
"When I woke up and saw this lump, I had no idea what it was - but it got larger and larger as days passed," Fergus said.
"After three days I went to A&E in so much pain - it felt like it was burning.
"I couldn't believe it when they found the venom of a black widow spider in my blood - I'd never even heard of one before.
"I was in hospital for days on all kinds of drips after the giant lump burst - that was when I thought I would lose my penis altogether."
Fergus had been staying at his mother's house in Cavan, in Ulster, and when he woke up on January 7 he noticed a "marble-sized" lump on his penis.
Confused, he initially dismissed it - but over the following days, the lump grew.
On the third day, his girlfriend Lyndsey Duffy, 21, urged him to visit A&E when the lump had reached the size of a golf ball, as well as turning purple.
They rushed to A&E at Cavan General Hospital where doctors insisted he would need to be seen by a specialist. He was quickly transferred to the larger Beaumont Hospital, in Dublin.
Fergus said he initially had "no idea" what it was.
"When I first went to hospital, the doctors didn't know either," he said.
"It was this constant burning pain and the lump kept getting bigger and bigger."
To make matters worse, just hours after he arrived in A&E, the huge cyst burst - leaving a giant hole where it had once been.
With doctors baffled, he stayed in hospital where he was hooked up to an IV drip of antibiotics as they feared an infection.
Fergus said: "The doctors kept coming in and out for swabs and blood samples. I was just lay there in bed - I couldn't walk or move even, because of the pain."
But it wasn't until several days had passed and Fergus' blood results came back that doctors finally sussed out what had caused the mystery lump.
Fergus claims that his test samples contained venom from a black widow spider - a dangerous red and black spider found worldwide.
While their venom is rarely fatal, a bite can cause muscle cramps and pain so intense it can be compared to appendicitis or a heart attack.
Fergus said doctors told him how lucky he was that it burst while in hospital - and that he could have been one of the few unlucky people for whom a black widow bite is deadly.
He said: "I got told I would probably have ended up dead if it hadn't burst in the hospital because it would likely have got infected.
"They said the venom could have spread and poisoned my blood system."
But luckily Fergus was treated quickly and dressings applied to protect the wound. A few hours after it burst, he recalled the pain subsiding.
Four days later he was discharged - although he continued having to take five tablets a day for a month once at home.
The construction worker was off work due to the pain of the wound and its healing, but this week returned to the job.
"The pain didn't ease properly until I had been home for around a week," he said. "I'm up and walking again now but it could have been so much worse."
Reflecting on the horrifying and painful experience, Fergus admitted he had feared the worst.
But looking back, he said: "I do find it a wee bit funny now because it is unusual. But it's also really scary - I had no idea what damage spiders could do."
A spokesperson for Beaumont Hospital said they could not comment on individual cases.
