For adults with constipation, the usual maximum MiraLAX dose at home is 17 grams (one capful) dissolved in 4–8 ounces of liquid once a day, even if the constipation feels severe.

Standard MiraLAX dosing

• For adults and people 17 and older, the typical and labeled dose is 17 g by mouth once daily, mixed well in 4–8 ounces of water, juice, or another beverage.

• It is generally recommended to use this dose for up to 7 days for occasional constipation, unless a clinician gives different instructions.

Severe constipation and safety

• Even for “severe” constipation, consumer guidance and product labeling advise not exceeding 17 g once per day unless a doctor has specifically told you to take more or more often.

• If there is no bowel movement within 1–3 days on the standard dose, or if symptoms are severe (strong abdominal pain, vomiting, bloating, blood in stool, or constipation lasting more than 7 days), you should contact a healthcare provider or urgent care/ER rather than increasing the dose on your own.

When higher doses are used

• Much higher polyethylene glycol doses (multiple capfuls) are sometimes used for “bowel clean-out” or colonoscopy prep, but these regimens are custom-designed and supervised by clinicians based on weight and overall health.

• Using large amounts on your own can cause dehydration, electrolyte problems, and worsening abdominal symptoms, especially if you have kidney, heart, or bowel disease.

What you can do right now

• If you are an adult without red‑flag symptoms, you can take 17 g once today (if you have not already), drink plenty of fluids, and wait up to 24–72 hours for effect.

• Seek urgent medical care or call your doctor now if you have: strong or worsening abdominal pain, vomiting, inability to pass gas, fever, blood in stool, a very distended belly, or constipation lasting longer than a week despite treatment.

This is general information and does not replace seeing a clinician; for “severe” symptoms, getting in-person medical evaluation is strongly recommended.