She was advised to consume less than half a liter of water per day.

A TikToker in Canada was hospitalised after drinking four litres of water for 12 days as part of a viral fitness challenge. The challenge, named 75 Hard, requires participants to drink about four litres of water for 75 days. It also includes following a structured diet with no alcohol or ”cheat meals”, two 45-minute workouts a day, reading 10 pages a day, and taking a daily progress photo, New York Post reported.

On Monday, Michelle Fairburn shared a video to TikTok on Monday about the challenge, which was first started by YouTuber Andy Frisella. She explained that she thought she had water poisoning, which can occur after you drink ”more than three to four litres of water in a few hours.”

”I think I have water poisoning. I don’t feel good at all,” Ms Fairburn said.

On the 12th day of her challenge, she said she didn’t feel good when she was going to bed the night before and had woken up several times in the night to go to the bathroom. She said she couldn’t eat, was nauseous, felt weak, and had been “on the toilet all morning.”

“I’m doing the 75 Hard, so I’m drinking an excessive amount of water,” she said. “I don’t know what to do.”

After a series of tests, the doctor told her that she had a severe sodium deficiency. Instead of the excessive four liters a day, she was advised to consume less than half a liter of water per day.

Extreme sodium deficiencies, or hyponatremia, can be life-threatening if left untreated, according to Mayo Clinic.

“Sodium deficiency actually can be fatal. So now I’m going to the hospital and they’re going to check everything and then apparently they can raise my sodium gradually. I’m still gonna do the 75 hard challenge, and I’m not gonna give up, but he says I have to drink less than half a liter of water a day. I cannot believe this is actually happening,” she said in the second video.

Notably, the fitness program was created in 2019 by a podcaster and CEO of a supplement company, Andy Frisella, who calls it ‘an Ironman for your brain’.

“You should consult your physician or other health care professional before starting 75 HARDTM or any other fitness programme to determine if it is right for your needs. Do not start 75 HARDTM if your physician or health care provider advises against it,” reads the website.