A soldier may have died fearing a fitness supplement he had taken would end his Army career, an inquest heard.
Lance Bombardier Richard Jones, 23, originally from Caerphilly, ordered Hemo-Rage on the internet to improve his performance in the gym.
The "super fit" tug-of-war player used a scoop of the powder on a couple of occasions before discovering it was not permitted in the Army.
L/Bdr Jones asked a friend to destroy the supplement but began fearing superiors would take a sample of his hair for testing.
Wiltshire and Swindon Coroner's Court heard L/Bdr Jones suffered hallucinations and increasing paranoia after returning from a sailing trip.
He claimed to have had an affair with a man during his engagement to wife Jodie Jones, who he married in 2011, at Larkhill Camp.
Colleagues discovered L/Bdr Jones' body at his flat in Larkhill, Wiltshire, along with a handwritten note stating: "You deserve better."
Former sergeant major Jamie Lavery, of Tiverton, Devon, told the three-day hearing L/Bdr Jones visited him on October 12 2012 - three days before his death.
"I asked him if he had been taking anything," Mr Lavery, who has since left the Army, said.
"He said he had taken a training supplement called Hemo-Rage.
"He said he hadn't taken it for a few weeks.
"I can't understand why he did, he was super fit.
"He said he didn't feel right.
"I said 'When you go back to the doc take it with you so you can put these fears of compulsory drug testing to bed'.
"I think it might have been playing on his mind that what he had been taking might be illegal in the Army."
Mr Lavery said drug testing happened at least yearly in the Army, though a unit could be tested two or three times.
There was no reference to L/Bdr Jones' alleged affair during the visit and he did not seem depressed, Mr Lavery said.
Hemo-Rage Black was banned in the UK in 2012, along with a number of sports supplements, as it contained DMAA (1.3 dimethylamylamine).
The Nutrex Research product has since been reformulated and does not contain the substance, it is understood.
Bombardier Stephen Mitchell told the inquest: "He said to me he had taken Hemo-Rage on one or two occasions.
"We had a drugs awareness briefing and he found out we weren't allowed to use it in the Army so he gave it to me and I disposed of it."
The inquest previously heard how L/Bdr Jones returned from a two-week sailing trip to the Canary Islands on October 11 2012.
After setting down his bag, he confessed to wife Jodie he had been in a relationship with a man before their wedding the previous year.
The couple attended Salisbury District Hospital later that night due to fears he was having a psychiatric breakdown.
They left before L/Bdr Jones saw a doctor and visited his GP the following morning, on October 12.
L/Bdr Jones became increasingly paranoid and returned to Salisbury District Hospital in the early hours of October 13.
Dr Katherine Welland described L/Bdr Jones as having "full capacities" and cooperating with medical staff.
"He said 'I have been hearing conversations' and people insulting him," Dr Welland said.
The couple, who were experiencing fertility problems, left the hospital before being seen by a mental health worker.
Mrs Jones went to visit family in Wales while her husband, of the 14th Regiment Royal Artillery, remained alone at their flat.
"He asked me was I going to divorce him and was our relationship over and I said no, we just needed some time apart," Mrs Jones said.
"Richard was a 23-year-old man and not for one second did I think the outcome would be what it was."
Mrs Jones, now of Bridgend, could not contact her husband on October 14 and she asked his colleagues to check him before she returned home.
The inquest heard L/Bdr Jones was found dead in his bed, with a handwritten note stating "You deserve better" in the kitchen.
Breaking down in tears, Mr Lavery said: "He was fit, keen, he would do anything for anybody.
"He would have had a great career."
The inquest, which is expected to conclude tomorrow, continues.