From my personal notes:
Creatine, in the form of phospho-creatine, is a vital energy buffer in cells, especially muscle cells and nerve cells. One may only need a low daily dose (500mg) of creatine monohydrate (or creatine HCl) to see an effect. It is often best to take the creatine with a little food and liquids, in order to avoid any increased stomach acid or nausea.
A large portion of the body's methylation capacity is spent on synthesizing creatine, so if you supplement with creatine you are also effectively freeing up a large portion of the body's methylation capacity for other uses.[1] Therefore, you might expect a large unpleasant reaction at first, but if you start low and go slow you should be able to tolerate low-dose creatine after a couple of weeks. As with B-vitamins, low-dose potassium can alleviate this reaction somewhat.
Reference
[1]
https://pubmed.ncbi.nlm.nih.gov/16400042/