Can Mag citrate cause very dry eyes and what about continued use for chronic constipation?

Have you talked to your physician about your chronic constipation? Magnesium citrate is not often advised as an ongoing solution for chronic constipation as, as you mentioned, it leeches the body of critical electrolytes (and fluids). It is more frequently recommended solely for rare or "occasional" use, or if specifically recommended as part of the prep for a GI procedure such as a colonoscopy.

There are many other OTC and Rx treatments available which are better suited for chronic constipation that will not cause you to become dehydrated and low on key electrolytes (such as potassium, magnesium, sodium, etc.). It is recommended that if you are having constipation more than occasionally that you discuss it with your doctor. S/he may suggest something like polyethylene glycol ("Miralax" or "Glycolax," available OTC or by Rx), a stool softener such as docusate ("Colace"), a fiber supplement such as Citrucel or Metamucil, occasional use of a laxative such as bisacodyl ("Dulcolax" ... but like Magnesium citrate, these have to be taken in moderation), or a Rx treatment for IBS or reduced motility. It all depends on what the actual *cause* for your chronic constipation turns out to be; different treatments target different causes and there are a number of things that can cause this one symptom! That's why it's important to consult a doctor when this becomes an ongoing issue.

I hope this answer is helpful. You may also want to speak with your pharmacist. The pharmacist is knowledgeable about the precautions and side effects of medications, including what's OTC, and may be able to answer some of your questions as well.

Good luck getting this all sorted out!