How much MiraLAX should you take to have a bowel movement?

October 9, 2025 •

3 min read

Approximately 4 million people in the U.S. experience frequent constipation, prompting many to seek relief from over-the-counter options. MiraLAX is a common choice for adults and adolescents aged 17 and over for occasional constipation.

Quick Summary

MiraLAX is used for occasional constipation in adults and adolescents 17+. It works gently by drawing water into the colon and typically produces a bowel movement in one to three days. Consult a doctor if constipation persists.

Key Points

Typical Adult Use: MiraLAX is typically used once daily for adults and adolescents 17+ for up to 7 days for occasional constipation.
How to Prepare: Dissolve the powder in 4 to 8 ounces of any hot, cold, or room temperature beverage and stir thoroughly before drinking.
Expect Gentle, Gradual Relief: MiraLAX typically produces a bowel movement within 1 to 3 days, providing gentle relief without harsh cramping or urgency.
Follow Instructions: Using more than recommended will not make it work faster and can increase side effects like diarrhea and bloating.
When to See a Doctor: If constipation persists for more than 7 days, or if you experience severe symptoms like rectal bleeding, worsening abdominal pain, or an allergic reaction, stop use and contact a healthcare provider.
Chronic vs. Occasional Use: While intended for short-term use, long-term use for chronic constipation may be prescribed by a doctor, but should never be self-prescribed beyond 7 days.
Hydration is Key: Drinking plenty of fluids while taking MiraLAX is important, as it helps the osmotic laxative draw water into the colon to soften stool.

Understanding MiraLAX: How it Works and Typical Use

MiraLAX, the brand name for polyethylene glycol 3350 (PEG 3350), is a popular and effective osmotic laxative used to treat occasional constipation. Its mechanism is gentle, as it works by drawing water into the colon to soften stool and increase stool volume, making it easier to pass. This process differs from stimulant laxatives, which force the colon muscles to contract. Healthcare providers often recommend its use for adults to ensure safety and effectiveness.

Typical Use for Adults

For most adults and adolescents aged 17 and older seeking relief from occasional constipation, MiraLAX is typically used once per day. The powder comes with a measuring cap on the bottle, or is available in single-dose packets.

How to Prepare and Take MiraLAX

Proper preparation is key to ensuring MiraLAX works effectively. The powder is typically tasteless and dissolves completely in a variety of beverages.

Choose your liquid: Mix the powder into 4 to 8 ounces of any beverage. Options include water, juice, coffee, tea, or soda.
Mix thoroughly: Stir the mixture until the powder is fully dissolved and there are no clumps.
Drink immediately: Consume the entire glass right away.
Stay hydrated: Since MiraLAX works by drawing water into the colon, drinking plenty of fluids throughout the day can improve its effectiveness.

How Long Does MiraLAX Take to Work?

Unlike faster-acting laxatives that can produce results in a few hours, MiraLAX is designed for gentle, gradual relief. Most people will have a bowel movement within one to three days of starting its use. It is important to be patient and continue taking the medication as directed. Using more than recommended can lead to side effects such as diarrhea, bloating, and cramping.

Duration of Use and Special Considerations

For occasional constipation, MiraLAX is intended for short-term use, and you should not take it for more than seven consecutive days without consulting a healthcare professional. If constipation persists beyond this period, it could be a sign of an underlying medical issue that requires evaluation by a doctor.

In cases of chronic constipation, a healthcare provider might recommend longer-term use of MiraLAX, but this should only be done under medical supervision. Its use may also differ for special procedures like a colonoscopy, in which case you must follow the specific instructions provided by your doctor.

Comparing MiraLAX with Other Laxatives


Feature	MiraLAX (PEG 3350)	Stimulant Laxatives (e.g., Senna, Bisacodyl)	Stool Softeners (e.g., Docusate)
Mechanism	Osmotic; pulls water into the colon to soften stool.	Stimulant; causes intestinal muscles to contract.	Emollient; adds water and fat to the stool.
Onset Time	1 to 3 days.	6 to 12 hours (oral).	12 to 72 hours.
Gentleness	Very gentle, with minimal cramping or urgency.	Can cause stomach cramps and more urgent bowel movements.	Gentle, but less effective for moving large masses.
Duration of Use	Up to 7 days for occasional use; can be used longer under a doctor's care.	Short-term use only, as long-term use can damage the bowel.	Can be used short-term.

Potential Side Effects and When to See a Doctor

While generally well-tolerated, MiraLAX can cause some minor side effects. Common ones include:

Bloating
Gas
Nausea
Stomach cramping

If you experience more severe side effects, you should stop taking MiraLAX and consult a healthcare provider immediately. These include:

Severe diarrhea
Rectal bleeding
Bloody stools
Severe or worsening stomach pain
Signs of an allergic reaction, such as hives or difficulty breathing

It is also crucial to contact a doctor if your constipation does not improve after seven days of use or if you have a sudden, persistent change in bowel habits lasting more than two weeks. A doctor can help determine the underlying cause and recommend the most appropriate course of action.

Conclusion

For adults and adolescents 17 years and older, MiraLAX is used for occasional constipation. By pulling water into the colon, this osmotic laxative provides gentle and effective relief, typically producing a bowel movement within one to three days. For safety, it is intended for short-term use of up to seven days, and any persistent constipation should be addressed by a healthcare professional. Following preparation instructions, along with staying adequately hydrated, is essential for achieving the best results with minimal side effects.

For more detailed information, consult the official MiraLAX website.

Frequently Asked Questions

MiraLAX is typically used once daily for adults and adolescents 17 years and older for up to seven days for occasional constipation.

MiraLAX usually produces a bowel movement within one to three days. Its gentle osmotic action takes time to draw water into the colon and soften stool, so it is not a fast-acting solution.

To mix MiraLAX, dissolve the powder in 4 to 8 ounces of a beverage such as water, juice, soda, coffee, or tea. Stir until fully dissolved and drink immediately.

Yes, you should follow the instructions for use. Using more than recommended will not make it work faster and can increase the risk of side effects like diarrhea and dehydration.

If you don't have a bowel movement within three days, it is not cause for immediate alarm, as it can take longer to work. However, if constipation persists after seven days of daily use, you should stop taking MiraLAX and consult a healthcare provider.

Over-the-counter MiraLAX is intended for occasional use for up to seven days. For chronic constipation, a doctor may prescribe longer-term use, but this should only be done under medical supervision.

MiraLAX is not approved for children under 17 years of age for over-the-counter use. The manufacturer states to ask a doctor before use for children 16 years of age or under. A doctor will determine the appropriate use for pediatric patients.