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HalfLytely and Bisacodyl Side Effects

Generic name: bisacodyl / polyethylene glycol 3350 / potassium chloride / sodium bicarbonate / sodium chloride

Medically reviewed by Last updated on Jan 31, 2021.

Note: This document contains side effect information about bisacodyl / polyethylene glycol 3350 / potassium chloride / sodium bicarbonate / sodium chloride. Some of the dosage forms listed on this page may not apply to the brand name HalfLytely and Bisacodyl.

For the Consumer

Applies to bisacodyl/polyethylene glycol 3350/potassium chloride/sodium bicarbonate/sodium chloride: oral kit

What are some side effects that I need to call my doctor about right away?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

  • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
  • Very bad belly pain.
  • Swelling of belly.
  • Very upset stomach or throwing up.
  • Bleeding from rectum or rectal pain.
  • Black, tarry, or bloody stools.
  • Throwing up blood or throw up that looks like coffee grounds.
  • This drug may cause you to be dehydrated or have electrolyte problems. Rarely, this may be severe or deadly. Tell your doctor right away if you get dizzy, pass out, feel tired or weak, or are unable to pass urine. Tell your doctor right away if you have a fast or abnormal heartbeat, seizures, headache, mood changes, confusion, muscle pain or weakness, more thirst, not hungry, dry mouth or eyes, severe upset stomach or throwing up, or a change in the amount of urine produced.

What are some other side effects of this drug?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

  • Bloating.
  • Feeling full.
  • Belly pain.
  • Upset stomach or throwing up.
  • Stomach cramps.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at

For Healthcare Professionals

Applies to bisacodyl / polyethylene glycol 3350 / potassium chloride / sodium bicarbonate / sodium chloride: oral kit


Mallory-Weiss tears are quite rare with administration of PEG-ELS. In one study it occurred in only 0.06% of over 3,000 patients.

Complete rectal prolapse was reported in a 71-year-old who had been given 4 L of PEG-ELS. The patient was observed for 2 days and had no recurrence of the prolapse.

During administration of PEG-ELS (4 liters) two deaths occurred in patients with end-stage renal failure following the development of vomiting, diarrhea and dysnatremia.[Ref]

Gastrointestinal side effects have been reported the most frequently. These have included nausea (17.1%), cramping (9.1%), abdominal fullness (22.3%), vomiting (5.9%) and overall discomfort (19.1%).

A small percentage of patients who received PEG-ELS have reportedly experienced Mallory-Weiss tears of the esophagus and esophageal perforation. In addition, at least one case of rectal prolapse has been reported.[Ref]


Dermatologic side effects reported with PEG-ELS have rarely included urticaria and dermatitis.[Ref]


Cardiac arrhythmias, especially increased ventricular ectopy, have been associated with PEG-ELS use.

The manufacturer notes an isolated case of asystole following ingestion of PEG-ELS in a geriatric patient (equal to or greater than 60 years of age).[Ref]

Cardiovascular side effects of PEG-ELS have included arrhythmias and asystole.[Ref]


A 70-year-old male developed shortness of breath, wheezing, skin flushing, and lowered blood pressure after drinking a second glass of PEG-ELS.[Ref]

Hypersensitivity side effects with PEG-ELS have rarely included anaphylaxis.[Ref]


Other side effects with PEG-ELS have included rhinorrhea.[Ref]


The manufacturer notes isolated reports of 'butterfly-like' infiltrate on chest X-ray following vomiting and aspiration of PEG-ELS and sudden dyspnea with pulmonary edema in geriatric patients (equal to or greater than 60-years-old).[Ref]

Respiratory side effects with PEG-ELS have included sudden dyspnea with pulmonary edema, and 'butterfly-like' infiltrate on chest X-ray.[Ref]

Nervous system

Tonic-clonic seizures have been reported in patients with and without previous history of seizures following administration of PEG-ELS (4 liters).[Ref]

Nervous system side effects have included tonic-clonic seizures.[Ref]

More about HalfLytely and Bisacodyl (bisacodyl / polyethylene glycol 3350 / potassium chloride / sodium bicarbonate / sodium chloride)

Consumer resources

Professional resources

Related treatment guides


1. Andorsky RI, Goldner F "Colonic lavage solution (polyethylene glycol electrolyte lavage solution) as a treatment for chronic constipation: a double-blind, placebo-controlled study." Am J Gastroenterol 85 (1990): 261-5

2. Bowden TA Jr, DiPiro JT, Michael KA "Polyethylene glycol electrolyte lavage solution (PEG-ELS). A rapid, safe mechanical bowel preparation for colorectal surgery." Am Surg 53 (1987): 34-6

3. DiPalma JA, Brady CE 3d "Colon cleansing for diagnostic and surgical procedures: polyethylene glycol-electrolyte lavage solution." Am J Gastroenterol 84 (1989): 1008-16

4. McBride MA, Vanagunas A "Esophageal perforation associated with polyethylene glycol electrolyte lavage solution." Gastrointest Endosc 39 (1993): 856-7

5. Raymond PL "Mallory-Weiss tear associated with polyethylene glycol electrolyte lavage solution." Gastrointest Endosc 37 (1991): 410-1

6. Korkis AM, Miskovitz PF, Yurt RW, Klein H "Rectal prolapse after oral cathartics." J Clin Gastroenterol 14 (1992): 339-41

7. Brinberg DE, Stein J "Mallory-Weiss tear with colonic lavage." Ann Intern Med 104 (1986): 894-5

8. "Product Information. HalfLytely and Bisacodyl (bisacodyl-PEG 3350 electrolyte (bisacodyl-PEG 3350 with electrolytes))." Braintree Laboratories, Braintree, MA.

9. Santoro MJ, Chen YK, Collen MJ "Polyethylene glycol electrolyte lavage solution-induced Mallory-Weiss tears." Am J Gastroenterol 88 (1993): 1292-3

10. Marsh WH, Bronner MH, Yantis PL, Kilgore JW, Rickoff MI "Ventricular ectopy associated with peroral colonic lavage." Gastrointest Endosc 32 (1986): 259-63

11. Schuman E, Balsam PE "Probable anaphylactic reaction to polyethylene glycol electrolyte lavage solution." Gastrointest Endosc 37 (1991): 411

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.