B12eficiency/headach. Lon term use of Nexium (esomeprazole) can some time cause atrophic gastritis, vit b12deficiency. But is relatively safe in recommended dose of 40 or 20 mgm daily domperidone is not available by prescription in us as it has not been approved by fda. It is a controversial drug even in uk and in my opinion should not be used long term, can cause chronic headaches, abdominal cramps, and dry mouth. Drinking water can help.