What is the best laxative for an 85-year-old man with chronic constipation?

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Last updated: July 3, 2025View editorial policy

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From the Guidelines

For an 85-year-old man with chronic constipation, polyethylene glycol (PEG) is the most recommended laxative due to its efficacy and safety profile, as evidenced by recent guidelines 1. The recommended dose is 17 grams (about one capful) dissolved in 8 ounces of water once daily. This medication works by drawing water into the intestines to soften stool and increase bowel movements without causing dependency or significant electrolyte disturbances. Some key points to consider when using PEG include:

  • Ensuring adequate hydration (6-8 glasses of water daily) to enhance its effectiveness
  • Gradually increasing dietary fiber to prevent constipation
  • Maintaining physical activity as tolerated to stimulate bowel movements
  • Potential side effects such as bloating, flatulence, and diarrhea, which are usually mild or moderate
  • The option to add stool softeners like docusate sodium (100-300 mg daily) if stool hardness is a particular issue
  • Stimulant laxatives like senna or bisacodyl should be used cautiously in older adults and only for short periods due to the potential for dependency and cramping. Given the patient's advanced age, it's crucial to rule out any underlying causes of constipation and start with lower doses, adjusting gradually as needed to minimize side effects like bloating or gas, as suggested by the guidelines 1.

From the FDA Drug Label

Purpose Stool softener Stimulant laxative Purpose Osmotic Laxative The best laxative for an 85-year-old man with chronic constipation is polyethylene glycol (PO), an osmotic laxative 2.

  • Senna (PO), a stimulant laxative, may also be considered, but polyethylene glycol (PO) is generally better tolerated and more effective for long-term use in the elderly 3.

From the Research

Treatment Options for Chronic Constipation in the Elderly

The treatment of chronic constipation in the elderly involves various agents, including bulk and fiber products, lubricating agents, stimulants, and osmotic laxatives.

  • Bulk and fiber products, such as dietary fiber and medicinal bulk, are popular therapeutic options for initial treatment of chronic constipation 4.
  • If fiber is not successful or tolerated, subsequent treatments may include saline osmotic laxatives, lactulose, or stimulants like senna or bisacodyl 4.
  • Polyethylene glycol laxative has been shown to be safe and effective as an initial or second-line agent for chronic constipation 4, 5.
  • Other emerging therapeutic strategies for managing constipation in the elderly include prucalopride, lubiprostone, neostigmine, and symbiotic yogurt containing Bifidobacterium and fructoligosaccharide 6.
  • Subcutaneous methylnaltrexone has been shown to be effective in the management of opioid-related constipation, which is common in nursing homes 6.
  • Sacral nerve stimulation and botulinum toxin are also being explored as potential treatments for chronic constipation in the elderly 6.

Efficacy of Specific Laxatives

  • A study comparing polyethylene glycol laxative to placebo over a 6-month treatment period found that 52.0% of patients receiving PEG laxative achieved treatment success, compared to 11% of those receiving placebo 5.
  • A study examining the safety and efficacy of a bulk laxative containing senna versus lactulose in geriatric patients found that the bulk laxative plus senna produced more frequent bowel habits than lactulose 7.
  • Senna has been shown to be a safe and effective laxative when used in appropriate dosage, and is considered the most physiological of all non-fibre laxatives 8.

Considerations for Elderly Patients

  • Elderly patients may require special consideration when selecting a laxative, as they may be more susceptible to adverse effects or interactions with other medications.
  • The use of laxatives in elderly patients should be carefully monitored, and patients should be advised on the proper use of bulk supplements to minimize the risk of adverse effects 8.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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