Help Patients Select Right Products for Constipation

OTC Guide2021 OTC Guide

Clinicians can play an important role in counseling patients about the 5 main OTC categories of laxatives to treat this gastrointestinal condition.

Constipation is one of the most common gastrointestinal complaints, and it generally occurs when individuals have fewer than 3 bowel movements per week.1

Symptoms may include dry and hard stools, a feeling of not fully emptying the bowels, and straining during bowel movements.1 Many factors can contribute to constipation, including a lack of exercise or not getting enough fiber; conditions such as diabetes, irritable bowel syndrome, or pregnancy; and drugs such as antidepressants, blood pressure medications, or opioids.1 Increasing fiber, fitness, and fluids are important lifestyle modifications to start with for patients with constipation. If these changes are not enough, health care providers can help patients select an appropriate OTC laxative to manage their constipation.


Before recommending laxatives, keep in mind that individuals with signs of appendicitis, such as lower abdominal pain, nausea, and vomiting, should seek medical attention immediately and not use laxatives. If a patient is using laxatives, they should take them separately from other medications to prevent reducing the efficacy of those drugs.1-3

Bulk Agents/Fiber

Fiber supplements such as Benefiber, Citrucel, and Metamucil improve the frequency of bowel movements by retaining water in the stool and increasing stool consistency and weight.2,3 These are typically powder formulations that can easily be mixed with liquid. Advise patients to drink at least 8 ounces of water with bulk-forming laxatives to prevent bloating, bowel obstruction, and cramping.1,4 Benefiber is safe to use in children and causes less bloating than other fiber products. Individuals who are immobile, on fluid restriction, or have trouble swallowing should avoid bulk laxatives.1 It generally takes approximately 12 to 72 hours to see results with fiber supplements.1


Medications such as bisacodyl (Dulcolax) and senna (Senokot) work by increasing intestinal motility.2 Stimulant laxatives generally take approximately 6 to 10 hours to work before a bowel movement occurs, with the most common adverse effect being cramping.2-4 Patients should start taking stimulant laxatives when starting opioid medications to prevent constipation.3,4 Patients with intestinal obstruction should avoid oral stimulant laxatives.2 Clinicians should monitor for signs of laxative abuse that can occur in patients with eating disorders and individuals who continue to use these medications long term.2-4 Symptoms may include dehydration, electrolyte disturbances, and severe diarrhea.4 Some combination products are available that contain more than 1 laxative. However, these may cause more adverse effects, so it is important to advise patients to read the drug facts label.


Osmotics include lactulose, magnesium hydroxide (Phillips' Milk of Magnesia), polyethylene glycol (PEG) 3350 (Miralax), and sodium phosphate enema (Fleet). They work by drawing water into the bowel surrounding the body tissues.2 They usually take 2 to 3 days to produce a bowel movement, although enemas work within 1 to 5 minutes.2 Patients recovering after a heart attack or after surgery can use osmotics to avoid straining during bowel movements. Osmotics also are another option for managing constipation in patients taking opioids. Patients at risk for electrolyte problems, such as those with heart or kidney failure or who are elderly or taking diuretics, should avoid osmotic saline laxatives that contain magnesium or sodium.4 Enemas can be used by individuals with fecal impaction, but they should not be used frequently to treat constipation. Glycerin (Pedia-Lax) suppositories are a type of osmotic laxative considered safe for use in children and infants to manage constipation and will usually produce a bowel movement in 15 to 60 minutes.2 Advise parents to use only 1 suppository in a 24-hour period.

PEG products also are often recommended to treat constipation in children.5 Neuropsychiatric adverse effects, such as anger, anxiety, depression, and paranoia, have been reported in children taking PEG.5 More studies need to be conducted to determine the long-term effects of PEG in children and whether it may be associated with safety concerns. Clinicians should advise parents about the possible risk of neuropsychiatric adverse effects with long-term use of PEG products in children.

Stool Softeners

Medications such as docusate sodium (Colace) moisten the stool by drawing water from the intestines to prevent straining during bowel movements and typically take 24 to 48 hours for results.2 Additionally, these products are often added to stimulant laxatives to treat constipation. Stool softeners are considered safe during pregnancy and can help with pregnancy-related constipation.6 Health care professionals also can recommend stool softeners to prevent constipation in pregnant patients taking iron supplements for anemia.6


Products such as mineral oil work by coating the bowel and stool with a waterproof film to promote bowel movements and make them easier to pass.2 Mineral oil should not be taken when lying down and should be separated by approximately 2 hours from meals as it may interfere with food digestion and absorption of nutrients and vitamins. Mineral oil should not be given to young children or bedridden elderly individuals because lipoid pneumonia can occur, which is caused by inhaling oil droplets into the lungs.2


1. Constipation. Cleveland Clinic. Updated November 7, 2019. Accessed May 8, 2021.

2. Laxative (oral route). Mayo Clinic. Updated May 1, 2021. Accessed May 7, 2021.

3. Bharucha A, Lacy BE. Mechanisms, evaluation, and management of chronic constipation. Gastroenterology. 2020;158(5):1232-1249.e3. doi:10.1053/j.gastro.2019.12.034

4. Bashir A, Sizar O. Laxatives. StatPearls. Updated September 23, 2020. Accessed May 7, 2021.

5. Dabaja A, Abbas M. Polyethylene glycol. StatPearls. Updated October 20, 2020. Accessed May 7, 2021.

6. Tobah YB. Is it safe to take stool softeners to treat pregnancy constipation? Mayo Clinic. April 11, 2020. Accessed May 7, 2021.



Jennifer Gershman, PharmD, CPh, is a drug information pharmacist and Pharmacy Times® contributor who lives in South Florida.

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