GoLYTELY typically triggers the first bowel movement about one hour after you start drinking it. If you’re past that window and nothing is happening, you’re not alone. Roughly 25% of all colonoscopies involve some degree of inadequate bowel preparation, and a slow or stalled response is one of the most common prep complaints.
The good news: a delayed response doesn’t necessarily mean the prep has failed. There are several things you can do to get things moving, and your doctor’s office can help with backup options if needed.
How to Tell If Your Prep Is Working
The goal of any colonoscopy prep is to empty your colon completely so the doctor has a clear view. You’ll know things are on track when your stool transitions from solid to loose to watery. The final benchmark is color and clarity. Dark or brown, murky liquid means you’re not there yet. Light orange and mostly clear is acceptable. Clear to yellow liquid means your colon is empty and you’re fully prepped.
If your stool is still dark and murky after finishing the entire prep solution, that’s a sign it hasn’t worked well enough. But if you’re only an hour or two in and feeling impatient, the prep may simply be working more slowly than expected.
Why GoLYTELY Can Be Slow or Ineffective
Several factors can make bowel prep take longer or work less completely. Chronic constipation is one of the biggest culprits, especially in older adults whose colons move waste more slowly. Diabetes independently reduces the speed at which your colon contracts, which means the prep solution sits longer without flushing things through. Opioid pain medications and certain antidepressants (tricyclics) also slow the gut considerably.
Other risk factors for a sluggish prep include obesity, a history of prior inadequate bowel prep, inflammatory bowel disease, previous colorectal surgery, and neurological conditions like Parkinson’s disease or dementia. If you were taking iron supplements, those should have been stopped at least five days before the colonoscopy, since iron leaves a dark residue that’s hard to wash out.
Sometimes the issue is simpler than any medical condition. Afternoon colonoscopies tend to have higher rates of inadequate prep, possibly because the timing of the prep doses is less ideal. Nausea or vomiting during prep can also prevent you from drinking enough of the solution to get the full effect.
What to Do If Nothing Is Happening
If you’re still waiting for results after the first hour or two, start by walking around. Light movement like pacing your house or gentle stretching can stimulate your gut. Massaging your abdomen in a clockwise direction (following the path of your colon) can also help.
Make sure you’re drinking the solution at the right pace. GoLYTELY works by volume: the large amount of liquid physically flushes your colon. If you’ve been sipping too slowly, try increasing your pace. The standard approach is drinking 8 ounces every 10 to 15 minutes until the jug is finished.
If nausea is slowing you down or causing vomiting, take a short break for 15 to 30 minutes to let the liquid already in your stomach move downstream. Then resume drinking at a slower rate. Keeping the solution cold and drinking it through a straw can reduce the taste-related nausea that makes the prep so difficult.
When to Call Your Doctor’s Office
If you’ve finished the entire prep and your stool is still brown and murky, or if you’ve been unable to keep the solution down, call the office that scheduled your colonoscopy. Don’t wait until you arrive for the procedure to mention the problem. Most gastroenterology offices have an after-hours line specifically because prep issues tend to happen in the evening or early morning.
Your doctor may recommend a “rescue” approach. Common options include adding an over-the-counter laxative like magnesium citrate, bisacodyl tablets, or senna to supplement the main prep. These work through different mechanisms than GoLYTELY, so they can provide an extra push when the primary solution hasn’t done enough on its own. Don’t add these on your own without checking first, since combining laxatives carries a risk of dehydration and electrolyte imbalances.
In some cases, the office will reschedule the procedure entirely and prescribe a different prep regimen or a longer preparation timeline. This is frustrating, but going in with poor prep often means the colonoscopy has to be repeated anyway, since the doctor can’t see the colon lining through residual waste.
What Happens If You Show Up Underprepared
If you arrive for your colonoscopy and the prep turns out to be inadequate, the doctor has a few options depending on how bad it is. Sometimes they can still complete the exam by flushing and suctioning fluid during the procedure, though this takes longer and may reduce the accuracy of the results. Small polyps can be missed behind residual stool.
If the colon is too dirty to examine safely, the procedure will be stopped and rescheduled. This means going through the entire prep process again, usually with a modified protocol. Patients who have failed a standard prep once are often given a longer lead time with dietary restrictions, a split-dose schedule (half the prep the evening before, half the morning of), or an added laxative to improve the odds the second time around.
How to Improve Your Chances Next Time
If you’re reading this before your prep or planning for a future colonoscopy, a few strategies significantly improve outcomes. Starting a low-fiber or clear-liquid diet two to three days before the prep, rather than just the day before, gives your colon less solid material to clear. This is especially helpful if you have chronic constipation or diabetes.
Split dosing is now the standard recommendation for most patients. Instead of drinking the entire 4-liter jug in one session the night before, you drink half in the evening and the other half early the morning of the procedure. This approach produces better colon cleanliness across nearly every study that has tested it.
If you take opioids or other medications that slow gut motility, mention this to your prescribing doctor well in advance. They may adjust your medications in the days leading up to the procedure or recommend an intensified prep protocol from the start, rather than waiting to see if the standard approach works.
Staying well hydrated in the days before prep also helps. A dehydrated colon absorbs more water from the prep solution, reducing its flushing power. Clear broths, water, and electrolyte drinks in the 48 hours before you start GoLYTELY give your body a head start.