What are the first-line laxatives for managing constipation?

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Last updated: June 20, 2025View editorial policy

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From the Guidelines

Polyethylene glycol (PEG) is the recommended first-line laxative for managing constipation, due to its efficacy in increasing spontaneous bowel movements (SBMs) and complete spontaneous bowel movements (CSBMs), as well as its relatively low cost and availability over-the-counter 1. The use of PEG as a first-line treatment is supported by its mechanism of action as an osmotic laxative, which helps to soften stool and increase bowel movements.

  • Key benefits of PEG include:
    • Efficacy in increasing SBMs and CSBMs
    • Low cost and availability over-the-counter
    • Relatively mild side effect profile, with most events being mild or moderate
    • Can be used in combination with fiber supplementation When using PEG, it is essential to stay well-hydrated and start with the lowest effective dose, typically 17g dissolved in 8oz of water daily.
  • Additional considerations for managing constipation include:
    • Lifestyle modifications, such as increased fiber intake (25-30g daily), adequate hydration (6-8 glasses of water daily), and regular physical activity
    • Monitoring for side effects, such as bloating, flatulence, and diarrhea, and adjusting the dose or treatment plan as needed
    • Seeking medical evaluation if constipation persists beyond two weeks despite using laxatives, as recommended by the american gastroenterological association 1.

From the FDA Drug Label

The FDA drug label does not answer the question.

From the Research

First-Line Laxatives for Constipation

  • The first-line laxatives for managing constipation include dietary fiber and medicinal bulk 2.
  • Bulk-forming laxatives, such as psyllium, bran, or methylcellulose, are often recommended as the initial treatment for constipation 3.
  • Osmotic laxatives, like polyethylene glycol, lactulose, or lactitol, can be used as a second-line treatment if bulk-forming laxatives are not effective 2, 3.
  • In palliative care patients, macrogol is often preferred as the first-line laxative due to its high effectiveness and good tolerance 4.

Specific Laxatives

  • Polyethylene glycol is a safe and effective laxative that can be used as an initial or second-line agent for chronic constipation 2, 5.
  • Lactulose is a commonly used osmotic laxative, but it can cause side effects like flatulence, bloating, and abdominal cramping 4, 3.
  • Senna and bisacodyl are stimulant laxatives that can be used if osmotic laxatives are not effective 2, 6, 3.
  • Lubricating agents, such as docusate, are still used in palliative care patients for prophylactic treatment or therapy of constipation 4, 6.

Treatment Approaches

  • The treatment of constipation should start with dietary and lifestyle changes, followed by the use of laxatives if necessary 3.
  • A laxative ladder approach has been proven successful in palliative care patients 4.
  • The management of opioid-induced constipation (OIC) typically involves the use of laxatives and stool softeners, with newer agents available for patients who do not respond to first-line therapies 6.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Current treatment options for chronic constipation.

Reviews in gastroenterological disorders, 2004

Research

Management of chronic constipation in patients with diabetes mellitus.

Indian journal of gastroenterology : official journal of the Indian Society of Gastroenterology, 2017

Research

Constipation--modern laxative therapy.

Supportive care in cancer : official journal of the Multinational Association of Supportive Care in Cancer, 2003

Research

Adverse effects of laxatives.

Diseases of the colon and rectum, 2001

Research

Management of Opioid-Induced Constipation in Hospice Patients.

The American journal of hospice & palliative care, 2018

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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