Mo Farah had to be airlifted to hospital after collapsing in his hotel room following a heart scare, the double Olympic long-distance champion has revealed.
The Britain was hospitalised for four days after losing consciousness after a routine training, which forced him to pull out of last month's Commonwealth Games in Glasgow.
But the 31-year-old insists the scare has not affected his plans to run in the 5,000m and 10,000m at the European Athletics Championships in Zurich this week.
"I had a tooth taken out because it was chipped and it got infected," Farah said. "I was in a bit of pain, but I went for a run, and when I came back from a run I literally collapsed on the bathroom floor, completely knocked out.
"I had my phone in my pocket, so when I woke up and became conscious I called Cam (Levins) my training partner, the guy who came third at the Commonwealth Games, and he came round and got me onto my bed.
"I was in so much pain from my stomach, and so he called an ambulance and it took me to hospital. I then had to be airlifted to the main hospital as they thought something was going on with my heart – it was just crazy.
"I was in hospital for four days and it was scary but these things happen so I missed quite a lot of training."
Farah, who also collapsed at the end of the New York half marathon in March, dismissed suggestions his decision to miss the Commonwealth Games was taking the easy way out.
"After the illness I did a couple of runs and I thought I hadn't lost very much," he continued. "But it takes a lot out of you mentally. I went back to the UK and had a lot of tests and they found nothing, but on the day where I was going to make my decision I was really struggling on a key session. I was nowhere near ready.
"I did one track session and Paula Radcliffe was timing me and she told me I should stop. Someone like Paula telling you to stop, you know there is something wrong and I just wasn't right – she could see that. It took a lot out of me.
"Later on Paula said I'd taken the easy option, which is not fair as she'd seen me struggle. I was quite disappointed, but if I'm going to turn up I have to be 100%. I'm not going to turn up in my home country and get beat."
Farah will return to action in the 10,000m final in Zurich on Wednesday.