Because the dragonfruit cactus is a cactus / succulent, it can more readily tolerate periods of dryness than it can tolerate long periods with too much moisture. Bear this in mind when when planting dragon fruit and choosing a location and preparing the soil and/or planting area.
Trouble in the mouth is the indication of low vitamin B complex in the body. A burning sensation in the mouth and tongue is a common effect of B vitamin deficiency. Deficiency of B complex also results in a swollen tongue, and people with this deficiency find it hard to swallow.
Vitamin B deficiency: One entity that's easily corrected that comes to mind as a vitamin D deficiency from a diet for in green leafy vegetables which contain vitamin B. We often see these cracks at the side of the mouth and call it Chelosis.