What Are Saline Laxatives

What Are Saline Laxatives

Saline laxatives contain active ingredients like magnesium, citrate, sulfate and phosphate ions that draws water into intestines to soften stool, increase colon contractions and result in discharge of softer stool. These ingredients can be dangerous to people with kidney failure. Some common type of these laxatives are Fleet Phospho-Soda, milk of magnesia and magnesium nitrate. All of these can be bought over the counter without prescription.

Fleet Phospho-soda

phosphateFleet Phospho-soda is a colorless, ginger lemon flavored solution used as bowel cleansing regimen in preparing patient for colons surgery or endoscopic examination. Normally total of 2 doses of 45ml each is instructed for bowel preparation with 10-12 hours gap in between doses. It usually produces a bowel movement in half to 6 hours.

It is not recommended for constipation treatment as it may cause severe dehydration, especially children below 12 years of age and elderly. Lots of fluids need to be taken prior and after the laxative intake. Hydration status and electrolyte levels (particularly potassium, calcium and phosphorus) should be monitored.

The use of this product should be avoided for patients with bowel obstruction, congestive heart failure, impairment of renal function. It is also not recommended in pregnant women and nursing mothers unless probable clinical benefit out-weights the possible risk as highlighted by doctor. As for diabetic patients, adjustment to insulin or oral anti-diabetic medication might be necessary before taking it.

Common side effects of taking this product includes nausea, vomiting, abdominal pain, bloating, fatigue, anal irritation and allergic reactions. Severe adverse reactions might happen including serious serum electrolyte disturbances and hypokalaemia if used towards patients of risk group above.

Milk of Magnesia

Milk of MagnesiaMilk of magnesia is a mild laxative appear milky white that is commonly used to treat constipation during pregnancy or during post-natal period after bulk-forming laxatives or stool softeners failed. It may takes 30 minutes up to 6 hours before producing a bowel movement.

For constipation, the recommended daily dose for adult is 6 to 8 chewable tablets, or 30 mL to 60 mL of oral suspension. For children aged 3 to 12 years old, the usual dose is 3 to 6 chewable tablets, or 15 mL to 30 mL of oral suspension per day. Do not use it beyond a week without medical advice.

This product is not recommended for children below 3 years of age unless prescribed by doctor. Patients with chronic kidney problems, pregnant women and nursing mothers should consult doctor before taking it.

Common side effects may include nausea, weakness, diarrhea and vomiting. Serious side effects is unlikely but if happen need to seek medical attention immediately, these include slow/irregular hear-beats, difficulty in breathing, decreased urination, dizziness, extreme thirst, bloody stools and rectal bleeding.


Before taking any of those saline laxatives, check with your doctor or pharmacist if you are allergies to it as this product may contain active ingredients that can cause allergic reactions. Read the product labels carefully and consult pharmacist or doctor if the product is suitable for you.

Fleet Phospho-soda should only be used for bowel cleanse under medical instruction and milk of magnesia should not be taken daily for more than a week to treat constipation. Overuse may cause persistent diarrhea, dehydration and electrolyte imbalance. Long term use of this product for constipation treatment can make your bowels dependent on the medication to function.