ClearLax and MiraLax are the same medication. Both contain identical active ingredients at the same dose: 17 grams of polyethylene glycol 3350 per capful. ClearLax is a store-brand version of MiraLax, and its packaging explicitly states “Compare to MiraLax® Active Ingredient.” The only real difference is price.
Same Active Ingredient, Same Dose
Both products deliver exactly 17 grams of polyethylene glycol 3350 (often shortened to PEG 3350) when you fill the cap to the indicated line. This is the standard over-the-counter dose for adults. Neither product contains inactive ingredients, fillers, or preservatives. The powder in each container is pure PEG 3350, which means there is no meaningful chemical difference between the two.
ClearLax is manufactured as a generic, or “store brand,” alternative. Generic over-the-counter medications are required to contain the same active ingredient in the same strength as the brand-name product they reference. That requirement is why ClearLax and MiraLax perform identically once you take them.
How They Work
PEG 3350 is an osmotic laxative. It works by holding water in the stool as it moves through your intestines, preventing your body from reabsorbing that water. The extra moisture softens the stool and increases its bulk, which triggers more frequent bowel movements. The compound itself is barely absorbed into your bloodstream. It passes through the digestive tract doing its job and then leaves the body.
You take it by mixing one capful of powder into 4 to 8 ounces of liquid (water, juice, coffee, tea, or soda all work). Stir until the powder dissolves completely. It’s tasteless and odorless, which is one reason it became popular compared to older laxatives. The standard routine is once daily, and most people see results within one to three days, though it can sometimes take longer to reach full effect.
Why the Price Difference
MiraLax is the original brand name, and brand-name products carry higher prices to recoup marketing and development costs. ClearLax and other generics (you’ll also see names like GaviLAX, GlycoLax, and store brands from major pharmacies) skip most of those costs. A bottle of ClearLax typically runs 20 to 40 percent less than the equivalent MiraLax bottle, depending on the retailer and size. Since the contents are chemically identical, choosing between them is purely a cost decision.
Side Effects Are the Same
Because the active ingredient is identical, ClearLax and MiraLax share the same side effect profile. The most commonly reported issues are bloating, gas, cramping, and nausea, all of which tend to be mild. Diarrhea can occur if the dose is too high or if you use it for an extended period. These products are generally intended for short-term use of up to seven days unless a doctor advises otherwise.
PEG 3350 is not recommended if you have a bowel obstruction or suspect one. Signs of obstruction include severe abdominal pain, vomiting, and inability to pass gas. If your constipation is accompanied by those symptoms, that’s a different situation than occasional irregularity.
Switching Between Brands
You can switch freely between ClearLax, MiraLax, or any other PEG 3350 generic without adjusting your dose or expecting a different response. There’s no transition period and no reason to taper off one before starting another. If MiraLax has been working for you, ClearLax will work the same way, and vice versa. The cap measurement system is standardized across brands at the 17-gram dose, so you prepare it the same way regardless of which bottle you pick up.