MiraLAX is a tasteless, odorless powder that you mix into a beverage and drink once a day. The standard adult dose is 17 grams of powder, which is one capful (filled to the white line on the measuring cap) or about one heaping tablespoon, stirred into 4 to 8 ounces of any beverage.
Step-by-Step Mixing Instructions
Fill the bottle cap to the top of the white section, which is pre-marked to measure exactly 17 grams. Pour the powder into 4 to 8 ounces of liquid. Water works, but so does juice, coffee, or tea. The liquid can be cold, hot, or room temperature.
Stir until the powder is completely dissolved. This is important: do not drink the mixture if you can still see clumps. MiraLAX dissolves more readily than many powdered supplements, but giving it a minute of stirring helps. If you’re preparing a larger batch (common before a colonoscopy prep), mixing it in advance and refrigerating for about 15 minutes helps it dissolve fully and makes it easier to drink.
One thing to avoid: do not mix MiraLAX with starch-based thickeners, the kind sometimes used by people who have difficulty swallowing. The combination doesn’t work properly.
When and How Often to Take It
The dose is once a day for adults and anyone 17 or older. There’s no strict rule about morning versus evening. Most people pick a consistent time that fits their routine. Some prefer morning so the effect happens during waking hours, while others take it in the evening. MiraLAX doesn’t cause sudden urgency the way stimulant laxatives do, so timing is more about personal preference than avoiding an emergency trip to the bathroom.
Don’t expect immediate results. MiraLAX typically takes one to three days to produce a bowel movement. It works by drawing water into the stool, softening it gradually. This is a slower, gentler process than a stimulant laxative, so patience on day one is normal.
What It Tastes Like
MiraLAX is designed to be nearly undetectable in a drink. The powder itself has no real flavor and dissolves clear. Most people mix it into water or juice without noticing a difference. If you’re sensitive to texture, mixing it into a strongly flavored beverage like apple juice or lemonade masks any faint grittiness. Chilling the mixture also makes it more pleasant to drink, especially if you’re taking a larger volume for a bowel prep.
Drinking Enough Water Alongside It
Because MiraLAX works by pulling water into your stool, staying well hydrated while using it matters. Drink plenty of water throughout the day, not just the 4 to 8 ounces you use to mix the dose. The liquid in the mixture alone isn’t enough to support the process. Adequate hydration helps the laxative work effectively and reduces the chance of bloating or cramping.
Common Side Effects
The most frequently reported side effects are mild and digestive: bloating, gas, nausea, and stomach cramping. These tend to be temporary and often lessen after the first couple of days. If cramping is bothersome, some people find that splitting the dose (half in the morning, half in the evening) reduces discomfort, though the standard recommendation is a single daily dose.
How Long You Can Use It
MiraLAX is sold as an over-the-counter product intended for short-term use, generally up to seven days. If constipation hasn’t improved after a week, that’s a signal to talk to a doctor rather than continuing on your own. Some people do use it longer under medical guidance, particularly for chronic constipation, but that decision should involve a healthcare provider who can rule out underlying issues like a bowel obstruction or other conditions that need different treatment.
MiraLAX for Children
MiraLAX is frequently recommended by pediatricians for childhood constipation, but the dose depends on the child’s weight and the situation. The over-the-counter label is only approved for adults and children 17 and older. For younger children, a doctor will typically prescribe a specific amount, often measured as a fraction of the adult capful, mixed into water or a clear, non-carbonated drink. Don’t guess at a child’s dose based on the adult instructions. Pediatric dosing is weight-based and varies significantly, so this is one where you need a provider’s specific guidance.
Colonoscopy Prep Is Different
If your doctor prescribed MiraLAX as part of a colonoscopy preparation, the instructions are completely different from the standard daily dose. Prep protocols typically involve mixing an entire bottle (238 grams or more) into a large container of liquid and drinking it over several hours. The goal is a thorough bowel cleanout, not gentle relief. Follow your doctor’s specific prep sheet for timing, volume, and which liquids to use. Preparing the solution in advance and refrigerating it makes the large volume significantly easier to get through.