What are the best management strategies for constipation in a 17-year-old patient?

Constipation Management for a 17-Year-Old

For a 17-year-old with constipation, start with polyethylene glycol (PEG) 17g once daily mixed in 8 ounces of water as first-line pharmacological treatment, combined with lifestyle modifications including adequate fluid intake (1.5-2 liters daily) and increased physical activity. 1

Initial Assessment and Approach

Before initiating treatment, identify any secondary causes including medications that may be contributing to constipation. 2 The goal should be achieving one non-forced bowel movement every 1-2 days. 2

First-Line Treatment Strategy

Polyethylene Glycol (PEG)

• PEG 17g (one heaping tablespoon) mixed in 8 ounces of water once daily is the recommended first-line pharmacological treatment based on strong evidence showing moderate certainty of benefit 1
• PEG increases complete spontaneous bowel movements by approximately 2.9 per week compared to placebo 1
• Response to PEG has been shown to be durable over 6 months 1
• Side effects include abdominal distension, loose stool, flatulence, and nausea, but the safety profile is excellent 1
• The powder must be fully dissolved before drinking; do not drink if clumps remain 3

Lifestyle Modifications (Essential Concurrent Measures)

• Increase fluid intake to 1.5-2.0 liters per day - this significantly enhances the effectiveness of fiber and laxative therapy 4
• Patients in the lowest quartile of fluid intake are most likely to be constipated, so fluid supplementation is particularly important for those with low baseline intake 1
• Encourage regular physical activity within the patient's capabilities 5
• Optimize toileting habits: attempt defecation twice daily, preferably 30 minutes after meals, and strain no more than 5 minutes 1, 5

Fiber Supplementation Considerations

For mild constipation, a trial of fiber supplementation can be considered before PEG or in combination with it. 1

• Psyllium is the fiber supplement with the best (though still low quality) evidence 1
• Standard dosing: one dose (typically one packet) in 8 ounces of liquid at the first sign of irregularity, up to 3 times daily for patients 12 years and older 6
• Important caveat: Fiber supplementation should only be used if the patient has adequate fluid intake (at least 1.5-2 liters daily) and is ambulatory 1, 5
• The chief side effect is flatulence; new users should start with one dose per day and gradually increase to avoid bloating 1, 6
• Daily fiber intake of 25g can increase stool frequency, and this effect is significantly enhanced when combined with adequate fluid intake 4

Second-Line Options for Inadequate Response

If PEG alone is insufficient after 7 days:

Add Stimulant Laxatives

• Bisacodyl 10-15 mg once daily can be added to the regimen 2
• Alternative: Senna 2 tablets twice daily 2
• These can be titrated up to 2-3 times daily if needed for persistent symptoms 2

Alternative Osmotic Laxatives

• Lactulose can be substituted if PEG is not tolerated 5
• Avoid magnesium-based laxatives (magnesium hydroxide) in patients with any renal impairment due to risk of hypermagnesemia 1, 5

Critical Pitfalls to Avoid

• Do not use docusate (stool softeners) as monotherapy - there is no proven benefit and it should not be considered first-line treatment 7
• Do not use bulk-forming laxatives or fiber supplements in patients with low fluid intake - this increases the risk of mechanical obstruction 1, 5
• Do not continue treatment beyond 7 days without reassessment - if constipation persists despite treatment, consider evaluation for fecal impaction or other complications 6
• Stop use and seek medical evaluation if rectal bleeding occurs, constipation lasts more than 7 days despite treatment, or the patient fails to have a bowel movement, as these may indicate a serious condition 6

Management of Fecal Impaction (If Present)

If digital rectal examination reveals fecal impaction:

• Glycerin suppository as first-line rectal intervention 2
• Bisacodyl suppository 10mg rectally once or twice daily as alternative 2
• Manual disimpaction with premedication (analgesic ± anxiolytic) may be necessary for severe impaction 2

Treatment Algorithm Summary

1. Start with PEG 17g once daily + ensure fluid intake 1.5-2 liters daily + encourage physical activity 1, 4
2. For mild symptoms or patient preference, can trial psyllium fiber (if adequate fluid intake) before or with PEG 1
3. If inadequate response after 7 days, add bisacodyl 10-15mg daily 2
4. If still inadequate, increase bisacodyl to 2-3 times daily or add alternative osmotic laxative 2
5. Reassess for fecal impaction or secondary causes if no improvement 2, 6