Jodie Symington, 23, from South Shields, will set off on a 12-day hike to Everest Base Camp.

She will then start the gruelling 27-mile course.

Her condition means the low oxygen levels and high altitude are potentially life-threatening.

Cystic fibrosis affects more than 8,000 people, and there are more than two million carriers in the UK.

The illness produces a thick secretion which makes breathing and digestion difficult and life expectancy for a sufferer is 31.

Ms Symington needs a daily 40-pill mix of antibiotics, vitamins, acid inhibitors and insulin, as well as physiotherapy and exercise as part of her treatment, and the condition will make the marathon much harder.

The marathon begins on May 29, the anniversary of when Sir Edmund Hillary and Tenzing Norgay first conquered Mount Everest.

It is one of the most demanding courses in the world with the terrain in the Himalayas, so top physical condition is imperative.

Her main aim is to raise funds for the Cystic Fibrosis Trust, and she hopes to collect more than £75,000.

She said: "I'll have doctors with me monitoring all my medication and how my body responds every step of the way. I'm mega-nervous, but very excited as well."

Anyone wanting to make a donation can click here.

You can also keep up to date with Jodie's progress by visiting her blog here.