The body of Aiden Webb, 22, from Norfolk, was found six days after he set off alone for the climb in June.
Girlfriend Bluebell Baughan had begged him to get help via a series of text and Facebook messages after he got lost on Mount Fansipan, an inquest heard.
Coroner Yvonne Blake recorded an open verdict into Mr Webb's death.
A hearing in Norwich was told Ms Baughan, who was also staying in Vietnam at the time, was in contact by phone after Mr Webb slipped and became hurt.
She said Mr Webb got lost, slipped, then cut his bicep on a rock and hurt his knee, after being forced off the main trail due to a landslide.
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Ms Baughan said he initially refused her pleas to let her call the authorities for help.
She became "very fraught", she said, as they realised he had missed the last cable car and had to stay the night dressed just in shorts.
In a series of messages, Mr Webb told how he had "got extremely lost", then later told her: "I am going to get pneumonia. I can't stop shivering."
He had also messaged to say: "I've just had a huge rock land on my arm. I need stitches or glue."
Mr Webb later said he would set off back down the mountain, and in his last text at 06.18 asked Ms Baughan to finally raise the alarm, but her reply failed to get through.
His body was eventually found in a stream down a ravine.
Local police concluded he had drowned while unconscious after falling into water.
A post-mortem examination was carried out in the UK after his parents asked for it not to be undertaken in Vietnam.
But Ms Blake said the medical cause of Mr Webb's death was "unascertained as he was embalmed".
Parents Simone Taylor and Trever Webb said in a written statement: "Aiden was such a joy to be around.
"We're incredibly close as a family and feel privileged to have been his parents."
A backpacker has described the moment she lost contact with her rock climber boyfriend - who died during an attempt to scale Vietnam's tallest mountain.