What is the recommended dosing regimen of liquid paraffin (mineral oil) for constipation in adults and children older than two years?

Liquid Paraffin (Mineral Oil) Dosing for Constipation

Liquid paraffin is generally not recommended as a first-line agent for constipation in adults or children due to safety concerns including aspiration risk and perianal burning, with polyethylene glycol (PEG) being the preferred osmotic laxative. 1

Adult Dosing (Ages ≥12 Years)

For adults and children 12 years and older, the FDA-approved dosing of liquid paraffin is 1 to 3 tablespoons (15 to 45 mL) taken only at bedtime, with a maximum of 3 tablespoons (45 mL) in 24 hours. 2

Key Administration Guidelines for Adults:

• Do not take with meals—liquid paraffin must be taken only at bedtime to minimize aspiration risk 2
• May be taken as a single dose or as directed by a physician 2
• The bedtime-only restriction is critical because aspiration of paraffin can cause severe lung injury, as documented in case reports of inadvertent administration 3

Pediatric Dosing (Ages 6 to <12 Years)

For children 6 to under 12 years of age, the FDA-approved dose is 1 to 3 teaspoons (5 to 15 mL) taken only at bedtime, with a maximum of 3 teaspoons (15 mL) in 24 hours. 2

Pediatric-Specific Considerations:

• Children under 6 years should not use liquid paraffin without consulting a physician 2
• Research evidence suggests an initial dose of 1 mL/kg/day for children with chronic functional constipation, which showed superior efficacy compared to lactulose 4
• For disimpaction in children, 3 mL/kg/day for 3 consecutive days (oral route) achieved 92.5% success rates 5

Why Liquid Paraffin Is Not First-Line

Despite evidence of efficacy in research studies, clinical guidelines explicitly list liquid paraffin under "laxatives generally not recommended" due to minimal efficacy and significant safety concerns. 1

Safety Issues That Limit Use:

• Aspiration risk: Paraffin aspiration causes chemical pneumonitis with bilateral pulmonary infiltrates, hemoptysis, and systemic inflammation 3
• Perianal burning and oil seepage: Reported in 27.5% of pediatric patients 5
• Minimal efficacy when used alone: Typically requires combination with other agents 1

Preferred Alternatives

Polyethylene glycol (PEG) 17g daily is the strongest first-line recommendation for both adults and children ≥6 months, with superior long-term safety and no aspiration risk. 6

Evidence-Based Algorithm:

1. First-line: Start with PEG 17g (1 heaping tablespoon in 8 oz water) once or twice daily 6
2. If inadequate response after 24-48 hours: Add bisacodyl 5-10 mg (adults) or 10-15 mg (adults) as rescue therapy 6
3. For children: PEG 0.8-1 g/kg/day is the laxative of first choice for ages ≥6 months 7
4. Reserve liquid paraffin: Only consider if PEG and stimulant laxatives have failed and aspiration risk can be minimized 1, 8

Research Evidence on Liquid Paraffin Efficacy

Meta-analysis of 287 pediatric patients showed liquid paraffin produced 4.94 more stools per week compared to lactulose (95% CI 4.28 to 5.61), but this evidence is rated low quality due to methodological concerns. 8, 9

Comparative Efficacy in Children:

• Liquid paraffin showed faster response and fewer side effects than lactulose in one pediatric trial 4
• Compliance rates were 95% in the first 4 weeks with liquid paraffin versus 90% with lactulose 4
• However, PEG showed no significant difference versus liquid paraffin (MD 0.70 stools/week, 95% CI -0.38 to 1.78) 8

Critical Warnings

Never administer liquid paraffin intravenously—case reports document severe bilateral pneumonitis requiring high-dose corticosteroids and antibiotics. 3

Additional Contraindications:

• Avoid in patients with swallowing difficulties or risk of aspiration 1
• Do not use in children under 6 years without physician supervision 2
• Avoid in patients with intestinal obstruction, ileus, or severe dehydration 1

Common Pitfalls to Avoid

• Taking liquid paraffin with meals or during the day increases aspiration risk—strict bedtime-only administration is mandatory 2
• Using liquid paraffin as monotherapy without addressing underlying causes (impaction, obstruction, metabolic disorders) leads to treatment failure 1
• Failing to transition to safer alternatives (PEG, stimulant laxatives) once disimpaction is achieved 1, 6