How to Administer MiraLAX (Polyethylene Glycol 3350)
For chronic constipation in adults, dissolve 17 grams (one heaping tablespoon or one packet) of MiraLAX powder in 4 to 8 ounces of any beverage (cold, hot, or room temperature) and drink once daily. 1
Standard Dosing for Constipation
- Dissolve 17 grams of powder completely in 4-8 ounces of liquid before drinking 1
- The liquid can be water, juice, coffee, tea, or any beverage of choice 1, 2
- Ensure the powder is fully dissolved - do not drink if there are any clumps 1
- Take once daily for up to 7 days for over-the-counter use 1
- For children 16 years and under, consult a physician before use 1
Higher Dose Regimens (When Prescribed)
For more severe constipation or when faster relief is needed:
- 17 grams dissolved in 8 ounces of water twice daily is recommended by the American Gastroenterological Association for chronic idiopathic constipation 3
- This twice-daily dosing (total 34 grams/day) increases complete spontaneous bowel movements by 2.90 per week compared to placebo 3
- Response to PEG is durable over 6 months of treatment 3
Critical Administration Points
Do not combine MiraLAX with starch-based thickeners used for patients with swallowing difficulties, as this creates an unsafe consistency 1
Mixing instructions:
- Stir the powder into the beverage until completely dissolved 1
- The solution can be consumed at any temperature (cold, hot, or room temperature) 1
- No specific timing with meals is required 3
Expected Timeline and Goals
- Best efficacy is typically seen in week 2 of treatment when used at standard doses 4
- For rapid relief, higher doses (68 grams in 500 mL) can produce bowel movements within 14-24 hours, though this requires physician supervision 5
- The goal is to achieve one non-forced bowel movement every 1-2 days 3, 6
Common Pitfalls to Avoid
Do not add fiber supplements (like psyllium) when treating medication-induced constipation, as they are ineffective and may worsen symptoms 6
Side effects to anticipate:
- Abdominal distension, loose stools, flatulence, and nausea are common 3
- These effects generally occur at treatment start and are usually transient 3
- No clinically significant electrolyte changes occur with standard dosing 5, 4, 7
When to Add Additional Agents
If MiraLAX alone is inadequate after 3-7 days:
- Add a stimulant laxative such as sennosides (2-3 tablets twice to three times daily) 3, 6
- Consider bisacodyl 10-15 mg daily if constipation persists 3
- Ensure adequate fluid intake throughout the day, especially in patients with baseline low fluid consumption 3
Special Populations
Elderly patients: MiraLAX 12 grams once or twice daily (or once every other day) is safe and effective in institutionalized elderly patients, with no clinically significant electrolyte disturbances 2
Antipsychotic-induced constipation: Use 17 grams twice daily as first-line therapy, combined with sennosides for optimal effect 6