Which OTC laxative should be avoided in patients with kidney disease due to risk of magnesium accumulation?

• A. Magnesium-based laxatives (e.g., magnesium hydroxide, milk of magnesia).
• B. Psyllium husk laxatives.
• C. Docusate sodium stool softeners.
• D. Senna-based stimulant laxatives.

Answer: (C)

Magnesium-containing laxatives should be avoided in kidney disease because the kidneys can’t clear magnesium effectively, allowing it to accumulate in the body. Excess magnesium can interfere with nerve and muscle function and may cause low blood pressure and dangerous heart rhythms, especially in people with impaired renal function. So laxatives that provide magnesium, like magnesium hydroxide, are the ones to avoid.

Laxatives that don’t add magnesium are safer alternatives in CKD. Psyllium husk, a bulk-forming laxative, works by increasing stool bulk with water and is generally safe when taken with enough fluids. Docusate sodium, a stool softener, helps mix water into the stool without introducing minerals. Senna-based stimulant laxatives stimulate bowel movement but do not contribute magnesium either; they’re not linked to magnesium accumulation, though long-term use should be approached with caution due to potential cramps and electrolyte shifts.