Magnesium Oxide (often labeled as MgO) is a basic, widely used medication in clinics and hospitals in Taiwan, typically appearing as a white tablet. It serves two primary clinical functions:
💡 Two Main Therapeutic Effects
1. Stool Softener and Constipation Relief (The most common reason for prescription)
This is the most common use of magnesium oxide. It acts as an “osmotic laxative.”
- Mechanism: When ingested, magnesium oxide is not fully absorbed by the body. Instead, it remains in the intestinal tract. Due to its osmotic pressure, it acts like a magnet, drawing water from the body into the intestines.
- Result: With increased water content in the intestines, dry and hardened stools are “soaked,” softened, and expanded in volume. This stimulates bowel movements and makes defecation easier.
🔗 For patients recovering from surgery (such as uterine prolapse surgery), doctors often prescribe magnesium oxide to ensure smooth bowel movements and strictly avoid the straining that could jeopardize surgical wounds.
2. Antacid (Stomach Medication)
As an alkaline substance, magnesium oxide also functions as an antacid.
- Mechanism: It can directly neutralize excess stomach acid.
- Result: It effectively relieves discomfort caused by hyperacidity, acid reflux, stomach pain, or heartburn.
⚠️ Precautions for Taking Magnesium Oxide
- Drink plenty of water: Since magnesium oxide works by “absorbing water” to soften stool, it must be taken with a large amount of water (it is recommended to drink 200–300 c.c. of warm water with each dose). If water intake is insufficient, the effectiveness of the stool softener will be significantly reduced.
- Common side effects: The most common side effects are diarrhea or excessively loose stools. If you experience diarrhea after taking it, the dosage may be too high. Usually, reducing the dose (e.g., taking half a tablet instead of one) will resolve the issue, or you should consult your doctor for an adjustment.
- Caution for patients with chronic diseases (especially those with impaired kidney function): Magnesium oxide contains “magnesium ions,” which are typically excreted in the urine by healthy individuals. However, for patients with poor kidney function or uremia, long-term or high-dose intake can lead to “hypermagnesemia” (excess magnesium in the blood). Therefore, patients with kidney disease must have their usage strictly evaluated by a physician before taking this medication.