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Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice.
Brand Name
Miralax
Generic Name
Polyethylene Glycol 3350
Active Ingredient
Polyethylene Glycol 3350Category
Osmotic Laxative [EPC]
Variants
6
Different strengths and dosage forms
| Strength | Form | Route | NDC |
|---|---|---|---|
| 17 g/17g | POWDER, FOR SOLUTION | ORAL | 11523-4357 |
| 17 g/17g | POWDER, FOR SOLUTION | ORAL | 11523-7268 |
| 17 g/17g | POWDER, FOR SOLUTION | ORAL |
This page is for informational purposes only and does not replace medical advice. Before using any prescription or over-the-counter medication for Miralax, you must consult a qualified healthcare professional.
| 17 g/17g | POWDER, FOR SOLUTION | ORAL | 11523-7234 |
| 17 g/17g | POWDER, FOR SOLUTION | ORAL | 76420-489 |
| 17 g/17g | POWDER, FOR SOLUTION | ORAL | 11523-7341 |
Detailed information about Miralax
Polyethylene Glycol 3350 is an osmotic laxative used for the treatment of occasional constipation. It works by retaining water in the stool to soften it and increase bowel movement frequency, typically producing a bowel movement in 1 to 3 days.
For the treatment of occasional constipation in adults and adolescents aged 17 years and older, the standard dose is 17 grams of powder once daily.
Because Polyethylene Glycol 3350 is minimally absorbed, no specific dosage adjustments are generally required for patients with mild to moderate renal impairment. However, patients with severe kidney disease should consult their doctor, as they may be more sensitive to the minor electrolyte shifts that can occur with laxative use.
There are no dosage adjustments required for patients with liver disease, as the drug is not metabolized by the liver and does not enter the portal circulation in significant amounts.
Elderly patients are at a higher risk for dehydration and electrolyte imbalances. While the standard 17-gram dose is generally used, healthcare providers may recommend more frequent monitoring or a lower starting frequency (e.g., every other day) for frail patients.
If you miss a dose, take it as soon as you remember. If it is almost time for your next scheduled dose, skip the missed dose and resume your regular schedule. Do not double the dose to 'catch up,' as this increases the risk of diarrhea and abdominal cramping.
An overdose of Polyethylene Glycol 3350 is rarely life-threatening but can cause significant discomfort.
> Important: Follow your healthcare provider's dosing instructions. Do not adjust your dose without medical guidance. If you have a sudden change in bowel habits that lasts over 2 weeks, consult a doctor before using this product.
Most patients tolerate Polyethylene Glycol 3350 well, but because it alters the fluid dynamics of the gut, some gastrointestinal symptoms are common. These usually resolve as the body adjusts to the medication or once the dose is discontinued.
Polyethylene Glycol 3350 is a safe and effective medication for most people, but it is not appropriate for everyone. The most critical safety rule is that it should never be used if you have a known or suspected bowel obstruction. Forcing bowel movements against a physical blockage can lead to serious complications, including intestinal perforation (a tear in the bowel wall).
No FDA black box warnings for Polyethylene Glycol 3350. Unlike some phosphate-based laxatives (which have warnings regarding acute phosphate nephropathy), PEG 3350 has a very high safety profile regarding kidney health in the general population.
There are no medications that are strictly 'contraindicated' in a way that causes a toxic chemical reaction with Polyethylene Glycol 3350. However, it should not be used simultaneously with other osmotic or stimulant laxatives unless directed by a doctor, as this significantly increases the risk of severe dehydration and electrolyte collapse.
Polyethylene Glycol 3350 must NEVER be used in the following circumstances:
Polyethylene Glycol 3350 is generally considered the preferred laxative for use during pregnancy.
Polyethylene Glycol 3350 is considered compatible with breastfeeding. Due to the extremely low maternal absorption, it is not expected to be excreted into breast milk in any detectable quantity. There have been no reported adverse effects on nursing infants whose mothers were taking PEG 3350. It is considered a 'Lactation Category L1' (Safest).
Polyethylene Glycol 3350 is a long-chain, linear polymer of ethylene oxide. Its molecular formula is H(OCH2CH2)nOH, where 'n' represents the average number of oxyethylene groups. The '3350' refers to its average molecular weight.
Its pharmacology is entirely based on osmotic pressure. In the colon, the PEG 3350 molecules form hydrogen bonds with water molecules. This 'traps' the water in the stool. Because the osmotic pressure in the intestinal lumen becomes higher than in the surrounding plasma, water is not reabsorbed. The resulting increase in fecal water content softens the stool and increases its volume. This volume expansion stretches the colonic walls, stimulating the mechanoreceptors that trigger the defecation reflex. It does not affect the absorption of nutrients or electrolytes in the small intestine.
Common questions about Miralax
Polyethylene Glycol 3350 is primarily used for the short-term treatment of occasional constipation in adults and children 17 years and older. It works as an osmotic laxative, meaning it draws water into the colon to soften the stool and make it easier to pass. It is also frequently used off-label by healthcare providers for the management of chronic constipation. Additionally, in higher doses and specific formulations, it is used for bowel cleansing before medical procedures like colonoscopies. It is generally not used for immediate relief, as it takes 1 to 3 days to produce a bowel movement. Always use it according to the label or your doctor's instructions.
The most common side effects associated with Polyethylene Glycol 3350 include abdominal bloating, gas (flatulence), and mild stomach upset or nausea. Some users may also experience stomach cramping or an increased sense of urgency to have a bowel movement. If the dose is too high, it can lead to diarrhea and watery stools. These symptoms are usually mild and tend to resolve once the medication is stopped or the dose is adjusted. If you experience severe abdominal pain or persistent diarrhea, you should contact your healthcare provider immediately. Most people tolerate the medication very well when used for the recommended 7-day period.
There is no known direct chemical interaction between Polyethylene Glycol 3350 and alcohol. However, it is generally advised to limit alcohol consumption while treating constipation. Alcohol is a diuretic, which can lead to dehydration by increasing urine output. Since Polyethylene Glycol 3350 works by drawing water into your intestines, being dehydrated can make the medication less effective and increase the risk of side effects like dizziness. Maintaining proper hydration with water or juice is essential for the laxative to work correctly. If you do choose to drink alcohol, do so in moderation and ensure you are drinking plenty of non-alcoholic fluids as well.
Polyethylene Glycol 3350 is generally considered safe for use during pregnancy and is often recommended as a first-line treatment for pregnancy-related constipation. Because the drug is not significantly absorbed into the mother's bloodstream (less than 0.2%), it does not reach the developing fetus in any meaningful amount. Clinical guidelines from major medical organizations suggest that osmotic laxatives like PEG 3350 are preferable to stimulant laxatives for pregnant patients. However, you should always consult with your obstetrician or healthcare provider before starting any new medication while pregnant. They can help ensure that your constipation isn't a sign of a different pregnancy-related complication. Proper hydration and fiber intake should also be prioritized alongside the medication.
Polyethylene Glycol 3350 is not an immediate-acting laxative and typically takes between 1 to 3 days (24 to 72 hours) to produce a bowel movement. This delay occurs because the medication must travel through the entire digestive tract to reach the colon, where it begins to draw in water and soften the stool. Because of this gradual onset, it is not the right choice for someone needing 'emergency' relief from constipation. If you have not had a bowel movement after three days of consistent use, you should consult your doctor. It is important to continue taking the daily dose as directed during this window, rather than increasing the dose out of frustration, to avoid sudden diarrhea.
Yes, you can generally stop taking Polyethylene Glycol 3350 suddenly without experiencing physical withdrawal symptoms, as it is not a stimulant and does not cause physical addiction. However, if you have been using it for several days, stopping abruptly may result in your constipation returning if you haven't addressed the underlying cause. To maintain regular bowel movements after stopping the drug, it is important to increase your dietary fiber intake and drink plenty of fluids. If you find that you cannot have a bowel movement without the help of the medication after 7 days of use, you should see a doctor. They can help determine if there is a chronic issue that requires a different treatment approach.
If you miss a dose of Polyethylene Glycol 3350, you should take it as soon as you remember. However, if it is almost time for your next scheduled dose, it is better to skip the missed dose and simply take your next dose at the regular time. You should never take two doses at once to make up for a missed one, as this can increase the likelihood of experiencing side effects like stomach cramps and diarrhea. Consistency is key for osmotic laxatives to work effectively. If you find yourself frequently forgetting doses, try taking the medication at the same time each morning. If you miss several days in a row, the time it takes to see results may be reset to the 1-3 day window.
Polyethylene Glycol 3350 does not cause permanent weight gain, as it contains no calories and does not affect your body's metabolism or fat storage. However, some users may notice a slight, temporary increase in the number on the scale due to water retention in the intestines. Because the drug works by drawing water into the bowel, you are effectively 'holding' more liquid in your digestive tract until you have a bowel movement. Conversely, some people may experience slight weight loss after the medication works and the accumulated waste is expelled. It is important to note that laxatives should never be used as a tool for weight loss, as this is dangerous and can lead to severe electrolyte imbalances and eating disorders.
Polyethylene Glycol 3350 can generally be taken with other medications, but there is a risk that it may reduce their absorption. Because PEG 3350 speeds up the movement of contents through your intestines, other oral drugs may have less time to be absorbed into your system. This is particularly important for medications that require very specific blood levels, such as seizure medications, blood thinners, or heart medications. To minimize this risk, most pharmacists recommend taking your other oral medications at least 2 hours before or 2 hours after your dose of PEG 3350. Always provide your doctor or pharmacist with a full list of all the supplements and prescriptions you are taking to ensure there are no specific concerns.
Yes, Polyethylene Glycol 3350 is widely available as a generic medication and is sold under many different store brands. The generic version is therapeutically equivalent to the original brand-name product, MiraLAX. Whether you choose the brand-name or the generic, the active ingredient and the concentration (17 grams per dose) remain the same. Generic versions are typically more cost-effective and are available in both individual packets and larger multi-dose bottles. When purchasing a generic, simply check the 'Drug Facts' label to ensure that Polyethylene Glycol 3350 is the only active ingredient. It is one of the most common over-the-counter gastrointestinal products found in pharmacies and grocery stores today.
Other drugs with the same active ingredient (Polyethylene Glycol 3350)
> Warning: Stop taking Polyethylene Glycol 3350 and call your doctor immediately if you experience any of these.
Polyethylene Glycol 3350 is intended for short-term use (7 days). Using it longer than recommended can lead to:
No FDA black box warnings for Polyethylene Glycol 3350. It is generally considered one of the safest laxatives available when used according to the label instructions.
Report any unusual symptoms to your healthcare provider. If you experience persistent vomiting or a complete inability to pass gas or stool, seek medical help immediately.
For short-term (7-day) use, no specific laboratory monitoring is required for healthy individuals. However, for those using it long-term under medical supervision, doctors may periodically check:
Polyethylene Glycol 3350 does not typically cause drowsiness or cognitive impairment. It is considered safe to drive or operate machinery while using this medication. However, if you experience dizziness due to dehydration, you should avoid these activities until you feel stable.
There is no direct chemical interaction between Polyethylene Glycol 3350 and alcohol. However, alcohol is a diuretic (it increases urine production), which can lead to dehydration. Since PEG 3350 also works by drawing water into the gut, combining the two can increase the risk of becoming dehydrated. It is best to limit alcohol intake while treating constipation.
When stopping Polyethylene Glycol 3350 after several days of use, no tapering is usually required. However, to prevent 'rebound' constipation, it is important to increase dietary fiber (fruits, vegetables, whole grains) and maintain high fluid intake as you stop the medication.
> Important: Discuss all your medical conditions with your healthcare provider before starting Polyethylene Glycol 3350. Be sure to mention if you have irritable bowel syndrome (IBS), ulcerative colitis, or Crohn's disease.
Polyethylene Glycol 3350 does not typically interfere with common blood or urine laboratory tests. However, if used as part of a high-dose bowel prep, it may temporarily affect tests for:
> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking. Even 'natural' products can change how your body responds to laxatives.
These conditions require a careful risk-benefit analysis by a healthcare provider:
There is potential cross-sensitivity with other polyethylene glycol-containing products. PEG is a common 'excipient' (inactive ingredient) in many tablets, topical creams, and even some COVID-19 mRNA vaccines. If you have had an anaphylactic reaction to any of these, you must be evaluated by an allergist before using PEG 3350 powder.
> Important: Your healthcare provider will evaluate your complete medical history before prescribing Polyethylene Glycol 3350. Do not assume that because it is OTC, it is safe for everyone.
Patients over the age of 65 are at a higher risk for constipation but also at a higher risk for the side effects of laxatives.
In patients with a GFR (Glomerular Filtration Rate) below 30 mL/min, Polyethylene Glycol 3350 should be used with caution. While it does not cause kidney damage, the shift of fluids into the bowel can lead to 'pre-renal' strain if the patient is not carefully hydrated. Dialysis patients should only use this medication under the strict guidance of their nephrologist.
No dosage adjustments are required for patients with liver cirrhosis or hepatic failure. The drug's action is localized to the gut lumen and does not rely on hepatic metabolism for activation or clearance.
> Important: Special populations require individualized medical assessment. Always consult with a specialist if you are pregnant, nursing, or managing chronic kidney disease.
| Parameter | Value |
|---|---|
| Bioavailability | < 0.2% |
| Protein Binding | 0% |
| Half-life (absorbed fraction) | 4–6 hours |
| Tmax (time to peak effect) | 24–72 hours (clinical effect) |
| Metabolism | None |
| Excretion | Fecal (>99%), Renal (<1%) |
Polyethylene Glycol 3350 is classified as an Osmotic Laxative. Related medications in this class include Lactulose, Sorbitol, and Magnesium Hydroxide (Milk of Magnesia). Among these, PEG 3350 is often preferred because it is not fermented by colonic bacteria, which generally results in less gas and bloating compared to lactulose or sorbitol.