This is what AI says about milk of Magnesia and why Doctors don't like it for long term use.

"Gastroenterologists are cautious about Milk of Magnesia (magnesium hydroxide) primarily because of the risk of hypermagnesemia (toxic magnesium levels), especially with prolonged use or in patients with kidney disease
. While it is generally safe for occasional, short-term relief, doctors prefer and recommend safer, more effective, and more sustained treatments for chronic constipation

Gastroenterologists are cautious about Milk of Magnesia (magnesium hydroxide) primarily because of the risk of hypermagnesemia (toxic magnesium levels), especially with prolonged use or in patients with kidney disease
. While it is generally safe for occasional, short-term relief, doctors prefer and recommend safer, more effective, and more sustained treatments for chronic constipation"