Water Fast with lemon and Cayenne

My friend is doing a water fast, but added a lemon and cayenne to her water. She also drinks about 4-5 liters of water a day.
It's been 19 days and so far so good with a few healing crisis's and a lot of mucus removed.
She can't use this forum and I am asking for her. Can she continue safely the fast as long as she fills OK?
Or it's time to get off the fast, since it's her first time fasting?