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Pharmacology for Nurses

30.3 Laxatives and Stool Softeners

Pharmacology for Nurses30.3 Laxatives and Stool Softeners

Learning Outcomes

By the end of this section, you should be able to:

  • 30.3.1 Identify the characteristics of laxative and stool-softener drugs used to treat gastrointestinal disorders.
  • 30.3.2 Explain the indications, actions, adverse reactions, and interactions of laxative and stool-softener drugs used to treat gastrointestinal disorders.
  • 30.3.3 Describe nursing implications of laxative and stool-softener drugs used to treat gastrointestinal disorders.
  • 30.3.4 Explain the client education related to laxative and stool-softener drugs used to treat gastrointestinal disorders.

Constipation is an unpleasant symptom or disorder that results in difficult stool evacuation or irregular and inconsistent stool passage, with common complaints like straining, incomplete or difficulty passing stools, or not defecating for a prolonged time. Stool may be small, round, hard, and lumpy when evacuated. Occasional constipation results in a feeling of fullness and wide-ranging discomfort. It often results from low fiber intake, dehydration, and a sedentary lifestyle. Certain medications can also promote constipation, such as anticholinergics and opioids.

Treatment involves increasing fiber intake, staying hydrated, and being physically active. Laxatives and stool softeners can help if constipation persists, but they should be used briefly to avoid dependency.

Bulk-Forming Laxatives

Bulk-forming laxatives relieve constipation within 24–72 hours by supplying the colon with an increase in dietary fiber. However, it is imperative that these products are taken with an adequate amount of water. If these products are not taken with enough water, it may result in worsening constipation as well as esophageal and/or stomach obstruction. Bulk-forming laxatives are commonly marketed over the counter as a fiber supplement to promote regularity and improve cardiovascular and digestive health. Bulk-forming laxatives should not be used in clients with symptoms of acute appendicitis, esophageal stricture or perforation, GI obstruction, or ileus. See Table 30.5 for adult dosing of these drugs.


Psyllium is an oral bulk-producing laxative that promotes natural elimination by absorbing water into its soluble fiber, softening feces and increasing stool bulk. It is considered safe and can help with occasional and chronic constipation relief. Psyllium supports digestive health, helps to maintain healthy glycemic control, promotes a healthy heart with cholesterol reduction, and promotes a healthy weight by reducing hunger (Proctor & Gamble, 2022). It is available over the counter in granules or powder to mix with water or juice. It is crucial to drink enough fluids to prevent complications like obstruction. Psyllium is also available as a wafer, but adequate water intake is essential to avoid choking and ensure its effectiveness. See Table 30.6 for additional information.


Another bulk-forming laxative, methylcellulose, is often used for both constipation and diarrhea for adults and children over age 3. Methylcellulose has also been used to promote regularity in irritable bowel syndrome (IBS) when taken as directed in capsule or powder suspension. As with its prototype, psyllium, it may take up to 3 days to work. Taking methylcellulose with several glasses of water will increase its effectiveness.

Calcium Polycarbophil

Calcium polycarbophil restores a balanced moisture level in the colon to form solid soft stool in cases of constipation or diarrhea. It promotes GI motility and regularity in conditions such as acute bowel syndrome, irritable bowel syndrome, and diverticulosis or after small-bowel surgery. Available in tablet and chewable forms, it should be taken with at least 8 ounces of water or juice to prevent choking and ensure its effectiveness.

Lubricant Laxatives

The goal of lubricant laxatives is to soften stool and lubricate the intestinal wall, making defecation easier and preventing straining. The onset of action for lubricant laxatives is typically 8–48 hours, depending on the client’s normal gastrointestinal transit time. Lubricant laxatives generally do not produce increased peristatic activity that causes abdominal cramping and spasms. These laxatives are often preferred by pregnant clients and older adults. If used frequently, they may interfere with the absorption of fat-soluble vitamins (A, D, E, and K).

Mineral Oil

Mineral oil serves as a lubricant laxative for constipation or fecal impaction and facilitates the elimination of barium residue in post-GI studies. It is available in various forms, including oral liquid and rectal enema. Mineral oil is not recommended for children under age 6 or individuals with swallowing issues or incapacitation due to the risk of lipid pneumonia if aspirated. Mineral-oil enemas act fast and should be administered with care to prevent complications like bowel perforation. See Table 30.5.

Stimulant Laxatives

Stimulant laxatives intensify intestinal peristalsis and increase the volume of intestinal water to relieve acute constipation that may be caused by high-dose opioid use. Stimulant laxatives are widely used and abused by the public. Approximately 40% of chronic constipation sufferers self-medicate with laxatives (Rao & Brenner, 2021). They are commonly used as part of bowel prep before colon procedures or surgeries, but are sometimes misused to eliminate calories in an attempt to lose or maintain weight. However, such abuse can result in electrolyte imbalances, dehydration, and potential harm to the gastrointestinal system's neuromuscular functions. Stimulant laxatives may also lead to anal leakage, causing discomfort and affecting a client’s confidence when leaving their home. See Table 30.5.


Bisacodyl is a stimulant laxative that directly irritates the sensory nerve endings in the smooth muscle of the intestine that induces peristalsis. Bisacodyl also stimulates an increased volume of water and electrolytes in the intestine. The action is directly responsible for the adverse effects of abdominal cramping, diarrhea, fluid, and electrolyte imbalances. Bisacodyl is typically used on a short-term basis to relieve constipation and should be taken as directed to minimize these side effects and complications.

Clinical Tip

Administering a Bisacodyl Suppository

  • If the suppository feels soft in the foil package, return the package to the refrigerator to harden before removing the wrapper.
  • Assist the client to a comfortable left side–lying position with their right knee raised to their chest.
  • With a gloved hand, use a finger to insert the pointed end of the suppository about 1 inch (2.5 cm) past the rectal sphincter.
  • Have the client hold the suppository in place as long as possible. Gently holding the client’s buttocks together may help the client retain the suppository as long as possible, for up to 20 minutes.
  • Assist the client with toileting.
  • Remove gloves and wash hands thoroughly.

Clinical Tip

Administering a Bisacodyl Enema

  • Shake the enema bottle well.
  • Assist the client to a comfortable left side–lying position with their right knee raised to their chest.
  • With a gloved hand, remove the protective shield and gently insert the enema tip into the rectum with the tip pointed toward the navel.
  • Gently squeeze the bottle until the contents are emptied into the rectum.
  • Remove the enema bottle from the rectum.
  • Have the client hold the enema contents in place as long as possible, for about 10 minutes. Gently holding the client’s buttocks together may help the client retain the contents.
  • Assist the client with toileting.
  • Remove gloves and wash hands thoroughly.

Castor Oil

Castor oil is an oral stimulant laxative used for constipation or as a bowel prep before a procedure. Castor oil is produced from the castor bean. When castor oil is in the intestine, lipase breaks down the castor oil into ricinoleic acid, a fatty acid that directly stimulates peristaltic activity of the colon to produce a bowel movement in 6–12 hours.

Castor oil is a liquid often mixed in fruit juice to mask the taste. Castor oil is contraindicated in pregnancy due to risk of inducing uterine contractions.


Senna is a laxative that converts senna glycosides to active aglycone in the colon to soften feces and stimulate peristalsis, for acute constipation and preprocedural bowel evacuation. Senna is available in tablets and as a syrup. Senna is also available in teas that are marketed for constipation relief.

Saline Laxatives

Saline laxatives are hyperosmotic oral solutions that retain water in the intestine to increase the bulk of the stool. Sometimes called “salts,” these laxatives are used when there is a need for a quick emptying of the lower bowel or intestine. The salts are absorbed, causing osmotic action to draw water into the intestinal lumen of the colon and causing the fecal mass to increase in size, or “swell.” The increase in bulk softens the stool for easier evacuation while also stretching the intestinal wall, causing peristaltic movement. Because the hypertonic solution offers a rapid emptying of the bowels, saline laxatives are not recommended for long-term or repeated use (Mayo Foundation for Medical Education and Research, 2023a). See Table 30.5.

Magnesium Citrate

Magnesium citrate, often referred to as citrate of magnesia or mag citrate, is a hyperosmotic saline cathartic laxative available as an oral solution. Magnesium citrate evacuates bowels before surgical or diagnostic procedures within 3–6 hours. Magnesium citrate is best given on an empty stomach with 240 milliliters (mL) of water. The solution is more palatable if chilled. Once opened, the effectiveness of magnesium citrate decreases.

Available in liquid or tablet form over the counter, magnesium citrate should be used as directed by the health care provider or per the instructions on the product label to avoid potential side effects or complications. It typically produces a bowel movement within a few hours of ingestion and is known for its effectiveness in promoting bowel regularity when needed.

Polyethylene Glycol

Polyethylene glycol is an osmotic laxative that is used for occasional and chronic constipation. This medication causes water to be drawn into the stool for easier evacuation. While it may take 2–4 days to produce results for chronic and occasional constipation, larger doses of polyethylene glycol are often used for bowel preparation before diagnostic and/or surgical procedures.

Available as a powder, a single heaping tablespoon of polyethylene glycol is reconstituted in 8 ounces of various beverages such as water, juice, soda, coffee, or tea. Stirring helps the powder dissolve, and the mixture should be consumed immediately. Typically, polyethylene glycol is taken once daily for up to 14 days, following the health care provider guidance for proper use and dosage.

Miscellaneous Laxatives

Miscellaneous laxatives are a group of drugs that do not fit into the more common categories of laxatives. These miscellaneous laxatives have different mechanisms of action and are used for the specific purpose of relieving constipation. See Table 30.5 for adult dosing of these drugs.


Linaclotide is classified as an accelerant of GI transit or guanylate cyclase-C agonist. Linaclotide is used to treat irritable bowel syndrome with constipation (IBS-C) and chronic idiopathic constipation, to improve bowel function, to eliminate constipation, and to decrease bowel irritation. Linaclotide is contraindicated if there is a suspicion of GI obstruction. If severe diarrhea occurs, linaclotide should be stopped and the provider contacted.


Sorbitol is a sugar alcohol or polyol that is commonly used as a sugar substitute in various sugar-free and "diet" food products. It is a sweet-tasting substance with approximately 60% of the sweetness of sucrose (table sugar). When taken orally, sorbitol has a laxative effect because it draws water into the intestines, softening the stool and promoting bowel movements. It is sometimes used to relieve constipation, especially in situations where a mild, osmotic laxative is needed.

Stool Softeners

Stool softeners are a type of laxative medication that helps to alleviate constipation by softening the stool, making it easier to pass. They work by increasing the water content of the stool, which helps to prevent and relieve constipation-related discomfort and straining during bowel movements. See drug emphasis Table 30.5.

Docusate Sodium and Docusate Calcium

Docusate sodium and docusate calcium are stool softeners often called surfactant laxatives. Docusate sodium and docusate calcium act like a detergent in the intestine, with anionic emulsifying and wetting properties to lower the surface tension of stool to allow penetration by water for easier defecation. Docusate sodium is available in tablets, capsules, and syrups. Docusate calcium is available as a capsule. Docusate is used prophylactically for clients at risk for constipation or fecal impaction who should avoid straining, such as postoperatively or after a myocardial infarction.

Docusate can be administered orally or rectally. Oral administration should be given with a full 8-ounce glass of water. The client should be encouraged to drink adequate fluid throughout the day. Oral solution (but not syrup) may be mixed with milk, fruit juice, or infant formula. Syrups are stored in an airtight bottle at room temperature. Rectal docusate is added to a microenema and administered via the rectum as an enema. Therapeutic effectiveness is achieved within 1–3 days.

Table 30.5 lists common laxatives and stool softeners with typical routes and dosing for adult clients.

Drug Routes and Dosage Ranges
Bulk-Forming Laxatives
(Fiberall, Konysl)
Oral (powder): 1 rounded tbsp (12 g) 3 times daily.
Oral (granules): 1 tsp (6 g) 1–3 times daily.
Oral (0.52 g capsule): 5 capsules with at least 8 oz of liquid, up to 3 times daily.
Oral: Start with two 500 mg caplets, increased as needed up to 6 times daily. Do not exceed 12 caplets per day.
Calcium polycarbophil
Oral: Two 625 mg tablets 1–4 times per day.
Lubricant Laxatives
Mineral Oil Oral (liquid): 1–2 tbsp at bedtime.
Rectal (enema): 1 bottle (120 mL) daily.
Stimulant Laxatives
Bisacodyl Pr
(Dulcolax, Correctol)
Oral (5 mg tablet): 1–3 tablets in a single dose daily.
Rectal (suppository): 10 mg (1 suppository) once daily.
Castor oil
Oral (liquid): 15–60 mL in a single daily dose.
Oral (tablet): 1 tablet once or twice daily.
Oral (liquid): 10–30 mL up to 2 times daily.
Saline Laxatives
Magnesium citrate
Oral (liquid): 6.5–10 fl. oz. daily.
Maximum dose: 10 fl. oz. in 24 hours.
Polyethylene glycol
Oral (powder): 17 g of powder dissolved in 4–8 oz of beverage daily. Do not use for more than 7 days.
Miscellaneous Laxatives
For IBS with constipation, oral: 290 mcg tablet once daily.
For chronic idiopathic constipation, oral: 145 mcg tablet once daily.
Rectal (enema): 120 mL daily as needed.
Stool Softeners
Docusate sodium
Oral: 1–3 100 mg softgels daily.
Docusate calcium
Oral: 240 mg softgel once daily for 2–3 days or until bowel movements are normal.
Table 30.5 Drug Emphasis Table: Laxatives and Stool Softeners (source:

Adverse Effects and Contraindications

Typical adverse effects of laxatives and stool softeners include abdominal cramping, diarrhea, electrolyte imbalances (particularly sodium and potassium), dehydration, rectal irritation, and gas and bloating.

Contraindications for laxatives and stool softeners include hypersentivitity to the drug or any of its components, intestinal blockage, appendicitis, and certain medical conditions such as Crohn’s disease or ulcerative colitis.

Laxatives should be used cautiously, as over time the body can become reliant on the drug to have bowel movements, leading to a condition known as laxative dependency. This can make it harder to have regular bowel movements without the use of laxatives.

Table 30.6 is a drug prototype table for laxatives and stool softeners featuring psyllium. It lists drug class, mechanism of action, adult dosage, indications, therapeutic effects, drug and food interactions, adverse effects, and contraindications.

Drug Class
Bulk-forming laxative

Mechanism of Action
Adds bulk to stool through water absorption, which promotes peristalsis and natural elimination
Drug Dosage
Oral (powder): 1 rounded tbsp (12 g) 3 times daily.
Oral (granules): 1 tsp (6 g) 1–3 times daily.
Oral (0.52 g capsule): 5 capsules with at least 8 oz of liquid, up to 3 times daily.
Short-term relief of occasional constipation and to promote regularity

Therapeutic Effects
Bowel movement within 12–72 hours
Drug Interactions
No significant interactions

Food Interactions
No significant interactions
Adverse Effects
Abdominal cramping
Electrolyte imbalances
Rectal irritation
Hypersensitivity to the drug or any of its components

Taking this product without adequate fluid may cause it to swell and block the throat or esophagus, causing choking; should not be taken if difficulty swallowing is present
Table 30.6 Drug Prototype Table: Psyllium (source:

Nursing Implications

The nurse should do the following for clients who are taking laxatives or stool softeners:

  • Prior to administering, assess the client’s medical history, current drug list, and allergies.
  • Educate the client regarding laxative and stool effects, such as abdominal cramping, diarrhea, and rectal irriation.
  • Assess client’s bowel habits including frequency, consistency, and ease of bowel movements. Monitor for changes with laxative and stool softener administration.
  • Monitor electrolyte levels, particularly sodium and potassium, to detect abnormalities.
  • Educate the client on lifestyle and dietary factors, such as increasing hydration and eating a healthy diet high in fiber to prevent constipation.
  • Educate client that these drugs are for short-term use, and long-term use could result in dependence.
  • Provide client teaching regarding the drug and when to call the health care provider. See below for client teaching guidelines.

Clinical Tip

Fecal Impaction and Bowel Obstruction

When administering laxatives and stool softeners, the nurse should assess the client for signs and symptoms of fecal impaction and bowel obstruction, which include severe abdominal bloating and cramping, stool leakage or sudden watery diarrhea (around impaction), rectal bleeding, small semi-formed stools, severe abdominal pain, vomiting, loud sounds from the abdomen, and inability to pass flatulence.

Client Teaching Guidelines

The client taking a laxative or a stool softener should:

  • Increase their dietary intake of fiber and increase their fluid intake, if not contraindicated, to help reduce the risk of constipation.
  • Report signs of muscle weakness, muscle cramps, fatigue, retrosternal pain, or numbness or tingling in the arms, legs and face, as these may be symptoms of serious adverse effects of the drugs.

The client taking a laxative or a stool softener should not:

  • Take these drugs long term, as they may result in dependence.

FDA Black Box Warning


Linaclotide is contraindicated in clients less than 2 years of age as it as been shown to cause death secondary to severe dehydration.

Case Study

Read the following clinical scenario to answer the questions that follow.

Mae Belle Smith is a 24-year-old logistics manager. Her job requires long hours of sitting at a desk with few breaks for hydration. Mae Belle presented to her provider with complaints of severe abdominal pain and distention and has not had a bowel movement in 6 days other than occasional leakage of scant amounts of liquid stool. Current medications include over-the-counter ibuprofen for occasional headaches.

Vital Signs Physical Examination
Temperature: 99.5°F
  • Head, eyes, ears, nose, throat (HEENT): Within normal limits
  • Cardiovascular: No jugular vein distention; S1, S2 noted
  • Respiratory: Clear to auscultation bilateral all lung fields
  • GI: Abdomen distended, lower abdomen firm, hypoactive bowel sounds in all 4 quadrants
  • Neurological: Within normal limits
  • Integumentary: No wounds noted; skin appropriate for age.
Blood pressure: 122/68 mm Hg
Heart rate: 93 beats/min
Respiratory rate: 20 breaths/min
Oxygen saturation: 99% on room air
Height: 5'7"
Weight: 125 lb
Table 30.7
The health care provider suspects Mae Belle has a fecal impaction. Which of the following medications should the nurse anticipate will be ordered?
  1. Methylcellulose
  2. Sorbitol
  3. Mineral oil
  4. Docusate sodium
After the impaction is resolved, which of the following medications should the nurse anticipate the health care provider will order to help promote the client’s natural bowel function?
  1. Psyllium
  2. Loperamide
  3. Linaclotide
  4. Ondansetron

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