MiraLAX Prep Guide

The MiraLAX prep is one of the most popular colonoscopy prep options, partly because it uses over-the-counter ingredients you can buy at any pharmacy. If your doctor has recommended a MiraLAX-based prep, this guide explains what to expect and how to make the experience as comfortable as possible.

What is MiraLAX prep?

MiraLAX (polyethylene glycol 3350) is an osmotic laxative powder that you mix with a clear sports drink — most commonly Gatorade. Unlike some prescription preps, MiraLAX is available without a prescription, which is why many doctors prefer it. It's typically combined with a stimulant laxative (like bisacodyl tablets) to boost effectiveness.

The concept is simple: you dissolve MiraLAX powder in Gatorade (or a similar clear electrolyte drink) and drink it over a set period. The MiraLAX draws water into your bowel, and the sports drink replaces electrolytes and adds flavor, making it easier to drink than plain medical-grade solutions.

Many people prefer this prep because the taste is more tolerable — you're essentially drinking flavored Gatorade, just with a slightly different texture. That said, it's still a bowel prep, and the experience of clearing your system is the same as with any other option.

How it works

Your doctor will give you specific instructions, but the general concept of a MiraLAX prep typically involves:

• A full bottle of MiraLAX powder (238g or 8.3 oz — the large "14-dose" bottle)
• 64 ounces of a clear sports drink (like Gatorade)
• Sometimes, bisacodyl (Dulcolax) tablets taken a few hours before starting the liquid

You mix the entire bottle of MiraLAX into the 64 ounces of Gatorade, shake or stir until dissolved, and refrigerate it. Then you drink it on the schedule your doctor provides — usually in a split-dose format.

Gatorade color matters

This is one of the most important rules for any MiraLAX prep:

Red, purple, and blue dyes can coat the lining of your colon and be mistaken for blood or other abnormalities during the colonoscopy. Stick with light, clear colors. When in doubt, hold the bottle up to the light — if you can't see through it, choose a different flavor.

Typical timeline

MiraLAX preps are usually done as a split dose. Your doctor's timing takes priority over this general outline:

Time	What to do
Day before — morning	Mix MiraLAX into Gatorade and refrigerate
Day before — all day	Clear liquids only (no solid food)
Day before — late afternoon	Take bisacodyl tablets if included in your instructions
Day before — around 6:00 PM	Start drinking the solution: 8 oz every 15 min until you've had about half (32 oz)
Morning of — about 5–6 hours before procedure	Drink the second half (remaining 32 oz), same pace
2 hours before procedure	Stop all liquids (most protocols)

Each half usually takes about an hour to drink. The key is maintaining a steady pace — don't rush, but don't fall behind either.

Tips and tricks

Chill everything

Cold MiraLAX-Gatorade is much easier to drink. Mix it in the morning and let it chill in the fridge all day. Some people even add it to an insulated bottle to keep it cold throughout drinking.

Mix early and well

MiraLAX takes a few minutes to fully dissolve. Give it a good shake or stir, then let it sit in the fridge. If you mix it right before drinking, you might notice a gritty texture. Mixing early prevents that.

Choose a flavor you already like

Since you'll be drinking 64 ounces of this, pick a Gatorade flavor you enjoy. Lemon-Lime is the most popular choice because it hides the MiraLAX taste well, but any approved color works. Some people split between two flavors (32 oz each) so they don't get tired of one.

Set a timer

An 8-ounce glass every 15 minutes means you need about four reminders per half. Use your phone or — even better — let the GentlePrep app remind you when it's time for the next glass.

Prepare your space

Stock the bathroom with soft wipes, barrier cream, your phone charger, and maybe a tablet for entertainment. You'll want everything within reach once things get going.

Stay active between glasses

Light walking helps the solution move through your system faster. Don't lie down right after drinking — gentle movement can reduce bloating and nausea.

What to expect

MiraLAX preps tend to be gentler on the stomach than some prescription options, but the results are the same — you'll be spending quality time in the bathroom. Here's the typical progression:

• 30–60 minutes after starting: The first bowel movements begin (sometimes sooner if you took bisacodyl tablets earlier).
• Hours 1–3: Frequent trips. Stools quickly become loose and watery.
• After Dose 1: Things usually slow down enough for you to get some sleep.
• After Dose 2: Your output should become clear or pale yellow. This is what you're aiming for.

Common side effects:

• Bloating: Usually temporary, especially early on.
• Mild nausea: Drinking more slowly and staying cool helps.
• Thirst: Drink additional clear liquids between doses. Hydration matters.
• Fatigue: You're not eating much and your body is working hard. Rest when you can.

When to call your doctor

Reach out to your doctor's office or on-call provider if you notice:

• Repeated vomiting that keeps you from finishing the prep
• Severe abdominal pain or cramping that doesn't pass
• Blood in your stool (more than a small amount)
• Signs of dehydration — dizziness, lightheadedness, very dark urine, rapid heartbeat
• No bowel movements after several hours of drinking the solution
• Chest pain, shortness of breath, or fainting

The MiraLAX-Gatorade prep is one of the more tolerable options out there, and many people are pleasantly surprised by how manageable it is. The GentlePrep app can walk you through every step with timed drinking reminders, stool progress tracking, and helpful tips along the way. Always follow your doctor's specific instructions.