Stool Softeners

Stool softeners are surfactants and lubricants that increase water penetration into stool or coat it to ease passage. Their evidence in chronic constipation is weak, and they should not be relied on alone.

Classification. Docusate sodium (surfactant); liquid paraffin and arachis oil (lubricants); glycerol (osmotic and lubricating).

• Docusate sodium 100 mg orally twice daily; up to 500 mg daily in divided doses.
• Docusate sodium rectal micro-enema.
• Arachis oil enema 130 mL, retained overnight, for impaction.
• Liquid paraffin; avoid.

Differences. Docusate also has a weak stimulant effect. Liquid paraffin has important harms.

• Short-term relief of hard stool after surgery, myocardial infarction or in haemorrhoids when straining must be avoided.
• Faecal impaction: arachis oil enema, then stimulant or osmotic treatment.
• Adjunct with a stimulant in people taking opioids.

Selection. Osmotic agents are more effective for chronic constipation and opioid-induced constipation.

Contraindications. Arachis oil in peanut or soy allergy. Liquid paraffin in older adults, children, pregnancy, swallowing disorders and bedbound patients.

Adverse effects. Docusate: cramps, diarrhoea, throat irritation. Liquid paraffin: lipoid pneumonia after aspiration, anal seepage, and reduced absorption of fat-soluble vitamins (A, D, E, K).

Interactions. Docusate may increase absorption of other drugs. Liquid paraffin lowers vitamin absorption.

Special groups.

• Pregnancy: docusate acceptable; avoid liquid paraffin (neonatal vitamin K deficiency and bleeding).
• Breastfeeding: docusate acceptable.
• Children: avoid liquid paraffin.
• Older adults: avoid liquid paraffin.

Monitoring. Stool frequency and consistency.

Referral and escalation. No response after 1 week, impaction persisting after rectal treatment, or abdominal pain with distension.