One of the most frequently asked questions about MiraLAX is: what is its generic name? The answer is polyethylene glycol 3350, commonly abbreviated as PEG 3350. MiraLAX is simply the brand name for this compound — and generic versions are widely available, equally effective, and substantially cheaper. This complete guide explains what polyethylene glycol 3350 is, how it works as a laxative, the correct dosage, the cost difference between brand and generic, and everything you need to use it safely.
MiraLAX / Polyethylene Glycol 3350 — Quick Reference
- Generic name: Polyethylene glycol 3350 (PEG 3350)
- Brand name: MiraLAX (Bayer)
- Other generic brand names: GlycoLax, ClearLax, GaviLax, and numerous store-brand versions
- Drug class: Osmotic laxative
- OTC status: Available without prescription in the US
- Available forms: White, odorless, tasteless powder — dissolved in 4–8 oz of liquid before taking
- Standard adult dose: 17g (one capful) once daily
- Onset of action: 1–3 days (not an immediate laxative)
- Primary use: Occasional constipation in adults and children over 17
What Is Polyethylene Glycol 3350? How Does It Work?
Despite its chemical-sounding name, polyethylene glycol 3350 is a remarkably simple and well-tolerated compound. It is a long-chain polymer molecule that is:
- Not absorbed by the gut — PEG 3350 passes through the digestive tract entirely unchanged
- Not digested — no enzymes in the gut break it down
- Not metabolised — it does not enter the bloodstream
PEG 3350 works as an osmotic laxative. Because of its large molecular size and hydrophilic (water-attracting) properties, it draws water into the colon from surrounding tissue. This increased water content in the stool softens it and increases the volume of intestinal contents, stimulating the natural muscular contractions of the bowel (peristalsis) and making stools easier to pass.
Unlike stimulant laxatives (senna, bisacodyl), PEG 3350 does not stimulate the intestinal nerves directly. This is why it is considered gentler, less likely to cause cramping, and safer for more frequent or longer-term use under medical guidance.
MiraLAX Generic vs Brand: What Is the Difference in Cost?
The cost difference between brand MiraLAX and generic polyethylene glycol 3350 is significant:
| Product | Size | Typical OTC Price | Price Per Dose (17g) |
|---|---|---|---|
| MiraLAX (Brand, Bayer) | 238g (14 doses) | $12–$18 | $0.86–$1.29 |
| MiraLAX (Brand, Bayer) | 510g (30 doses) | $20–$28 | $0.67–$0.93 |
| Generic PEG 3350 (store brand) | 238g (14 doses) | $6–$10 | $0.43–$0.71 |
| Generic PEG 3350 (store brand) | 510g (30 doses) | $10–$16 | $0.33–$0.53 |
| Generic PEG 3350 (bulk 850g) | 850g (50 doses) | $14–$20 | $0.28–$0.40 |
Generic PEG 3350 is approximately 40–55% cheaper than brand MiraLAX — for the exact same active ingredient at the exact same dose. Store-brand versions (CVS, Walgreens, Target, Costco, Amazon) contain pure polyethylene glycol 3350 and are completely bioequivalent. There is no reason to pay the brand premium unless you have a specific preference for the MiraLAX packaging or brand.
Polyethylene Glycol 3350 Dosage: How Much to Take
The standard adult dosage for constipation relief:
| Age Group | Dose | Frequency | Maximum Duration (OTC) |
|---|---|---|---|
| Adults and children 17+ | 17g (one full measuring capful) | Once daily | 7 days without consulting a doctor |
| Children under 17 | As directed by physician | As directed | Only under medical supervision |
How to Take PEG 3350 Correctly
- Dissolve the 17g powder in 4–8 oz (120–240ml) of any beverage — water, juice, coffee, tea, or a soft drink. PEG 3350 is odourless and virtually tasteless; it dissolves completely without altering the flavour of the drink significantly.
- Stir until completely dissolved — this typically takes less than 30 seconds
- Drink the entire glass
- Can be taken with or without food, at any time of day
- Stay well hydrated throughout the day — adequate fluid intake improves the laxative effect
- Do not use for longer than 7 days without medical guidance for OTC use
How Long Does MiraLAX/PEG 3350 Take to Work?
This is one of the most important things to understand about polyethylene glycol 3350: it is not a rapid-acting laxative. Unlike stimulant laxatives that act in 6–12 hours, PEG 3350 typically takes:
- 1–3 days for the first bowel movement after starting treatment
- Some patients experience relief within 24 hours; others may need 2–3 days of daily dosing
- Once regular bowel movements are re-established, many people discontinue use
This delayed onset is expected and normal. If you need relief within hours (e.g., before a medical procedure or from severe discomfort), a stimulant laxative or suppository may be more appropriate — consult your pharmacist or doctor.
Is MiraLAX Safe for Long-Term Use?
PEG 3350 is approved for short-term OTC use (up to 7 days). For chronic constipation, many physicians recommend it for longer-term use — but this should be under medical supervision. The key safety considerations are:
- PEG 3350 is not absorbed systemically, making it one of the safest laxatives for extended use under medical guidance
- It does not cause the "lazy bowel" dependence associated with chronic use of stimulant laxatives
- Long-term use without investigating the underlying cause of constipation is not ideal — chronic constipation warrants medical evaluation
- For children, MiraLAX has been widely used off-label for chronic constipation under paediatric supervision, though it is only FDA-approved for adults 17 and over OTC
Side Effects of Polyethylene Glycol 3350
PEG 3350 is generally very well tolerated. Side effects are typically mild:
Common (affecting 5–15% of users)
- Nausea — usually mild; take with food if this occurs
- Bloating or abdominal cramping — more common at higher doses
- Gas (flatulence)
- Diarrhoea — if diarrhoea develops, skip a dose and reduce to half dose
Serious Side Effects (seek medical attention)
- Severe diarrhoea or watery stools lasting more than 2 days — may indicate electrolyte imbalance
- Allergic reaction: rash, swelling, difficulty breathing (rare)
- Rectal bleeding — do not use PEG 3350 if rectal bleeding is present; this requires medical evaluation
Who Should NOT Use MiraLAX / PEG 3350?
- Bowel obstruction — PEG 3350 can cause dangerous pressure against an obstruction
- Rectal bleeding or bloody stools — requires medical evaluation before using any laxative
- Sudden change in bowel habits lasting more than 2 weeks — needs medical assessment to rule out serious underlying conditions
- Known allergy to polyethylene glycol
- Kidney disease — use with caution; consult your doctor
MiraLAX vs Other OTC Laxatives
| Laxative Type | Example | How It Works | Onset | Best For |
|---|---|---|---|---|
| Osmotic (PEG 3350) | MiraLAX / PEG 3350 | Draws water into colon | 1–3 days | Occasional constipation; gentle and well-tolerated |
| Stimulant | Senna, bisacodyl (Dulcolax) | Stimulates intestinal nerves | 6–12 hours | Quick relief; before procedures |
| Bulk-forming | Psyllium (Metamucil) | Adds bulk to stool | 12–72 hours | Long-term bowel health; requires adequate water |
| Stool softener | Docusate (Colace) | Softens hard stools | 12–72 hours | Prevention; post-surgery; haemorrhoids |
| Osmotic (saline) | Milk of Magnesia | Draws water into colon | 0.5–6 hours | Faster osmotic relief; short-term use |
Need MiraLAX or Generic PEG 3350?
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Buy MiraLAX Online Omeprazole for Heartburn Loperamide for DiarrhoeaFrequently Asked Questions About MiraLAX Generic
What is the generic name for MiraLAX?
The generic name for MiraLAX is polyethylene glycol 3350, also written as PEG 3350. This is the active ingredient in all MiraLAX products as well as every generic equivalent.
Is generic MiraLAX as effective as brand MiraLAX?
Yes — 100%. Generic PEG 3350 contains the same active ingredient at the same dose as brand MiraLAX. Both are white, odourless, tasteless powders containing pure polyethylene glycol 3350. There is no therapeutic difference.
How long can I use MiraLAX?
OTC use is recommended for up to 7 days without consulting a doctor. For longer use (prescribed for chronic constipation), follow medical guidance. PEG 3350 is considered safe for extended use under supervision as it is not absorbed and does not cause the bowel dependence associated with stimulant laxatives.
Can I mix MiraLAX with any drink?
Yes — PEG 3350 dissolves in virtually any liquid without affecting taste significantly. Water, juice, coffee, tea, and soft drinks all work well. Some people add it to smoothies.
Conclusion
MiraLAX's generic name is polyethylene glycol 3350 (PEG 3350) — a non-absorbed osmotic laxative that relieves constipation by drawing water into the colon to soften stool. Generic PEG 3350 is available OTC without a prescription at roughly 40–55% of the cost of brand MiraLAX, with identical efficacy. Understanding that onset takes 1–3 days (not hours) is the most important practical point for new users. For occasional constipation, PEG 3350 is one of the safest and most tolerable OTC options available. Visit our MiraLAX product page to order with fast delivery.
