The Belgian press had reported she might take her life after Rio, but she rejected the speculation at a news conference following her victory.
She said she was "still enjoying every little moment".
"When the moment comes when I have more bad days than good days, then I have my euthanasia papers, but the time is not there yet," she told journalists in Rio.
Euthanasia is legal in Belgium.
The 37-year-old suffers from a degenerative muscle disease that causes constant pain, seizures, paralysis in her legs and leaves her barely able to sleep.
She was just 14 when the diagnosis was made and gradually her life became "a constant battle".
In spite of it, she achieved a distinguished career in wheelchair racing, winning 100m gold and 200m silver in the 2012 London Olympics, and now a silver medal in Rio.
But the punishing training schedule is proving too hard. This was her last Paralympics, she confirmed, making her Rio achievement bitter-sweet.
"It`s a feeling of `Yes, I won a silver medal`", she told the BBC , "But there is also another side to the medal, the side of suffering and of saying goodbye to the sport. Because I love the sport, sport is my life."
The possibility of euthanasia gave her the courage to keep going as long as she has, she says, adding that Euthanasia must not be characterised as "murder."
"It gives a feeling of rest to people," she says. "I know when it`s enough for me, I have those papers."
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