A university student high on party drug mephedrone allegedly cut off his own penis after stabbing his mother.
The unidentified teenager, who had returned to his family home in Haywards Heath, West Sussex, for the Christmas holidays, is believed to have castrated himself with a knife after he attacked his mother.
He is believed to have taken mephedrone, a class b drug commonly known as meow meow, shortly before the alleged incident.
A source close to the family told the Mirror: "He is normally a lovely lad and very bright. But unfortunately, he had started dabbling in drugs.
"He had come home from university for Christmas. It looks like he took mephedrone and completely flipped out, attacking his mum and then himself."
The man, who has not been named, was found hanging from a bedroom window with blood pouring from his groin when emergency services arrived.
Sussex Police were investigating.
"Officers are at the scene collecting evidence and speaking to residents about what they might know," DI David Springett said.
"We are not looking for anyone else in connection with this incident."
Mother and son were both said to be in a stable condition at the Royal Sussex County and University College London hospitals respectively.
Until 2010, mephedrone was legal in the UK but was reclassified as a class B drug and is illegal to sell and to possess.