Constipation in Adults - Chronic, Functional Drug Summary

Last updated: 23 July 2026
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GIT Regulators, Antiflatulents & Anti-inflammatories

Drug Dosage Remarks
Prucalopride 1-2 mg PO 24 hourly Adverse Reactions
  • GI effects (nausea/vomiting, diarrhea, dyspepsia, abdominal pain, flatulence, rectal hemorrhage, decreased appetite, abnormal GI sounds); Other effects (headache, dizziness, fatigue, pollakiuria)
Special Instructions
  • Avoid use in patients requiring dialysis, patients with intestinal perforation or obstruction, inflammatory intestinal conditions
  • Use with caution in patients with hepatic, cardiovascular, or pulmonary disease, neurologic or psychiatric disorders, cancer or AIDS, other endocrine disorders, hereditary problems of galactose intolerance, Lapp lactase deficiency, or glucose-galactose malabsorption

Laxatives, Purgatives

Drug1 Available Strength Dosage Remarks
Bulk-producing Laxatives
Ispaghula
(Ispaghula husk,
Plantago ovata
seed shells,
Psyllium) 		3.25 g/5 g sachet 1 sachet in >150 mL liquid PO 8-24 hourly Adverse Reactions
  • Large quantities may temporarily increase bloating, flatulence and abdominal distension; hypersensitivity reactions; intestinal/esophageal obstruction and fecal impaction especially if swallowed dry
Special Instructions
  • Take with plenty of fluid
  • Avoid in patients with difficulty in swallowing, those with pre-existing fecal impaction, intestinal obstruction or colonic atony
3.5 g/sachet
5 g/sachet
6 g/sachet
Methylcellulose Powder 2 g in liquid PO as single dose 
May increase to 2 g PO 8 hourly
Contact Laxatives (Stimulant Laxatives)
Bisacodyl 5 mg/tab 1-2 tab PO 24 hourly at bedtime Adverse Reactions
  • GI effects (colic, cramps, abdominal distension, diarrhea, nausea/vomiting); prolonged use or higher doses can cause diarrhea with excessive loss of water and electrolytes especially K; atonic non-functioning colon can also occur; hypersensitivity reactions have been reported
  • Suppository can cause irritation and repeated use can cause proctitis or sloughing of epithelium
Special Instructions
  • Avoid long-term use
  • Avoid in patients with intestinal obstruction or acute surgical abdominal conditions, patients with IBD or in patients with severe dehydration
  • Suppository should be avoided in patients with anal fissures, proctitis or ulcerated hemorrhoids
10 mg/suppository 1 suppository rectally 24 hourly
Castor oil 4.4 mL/5 mL 45 mL PO 24 hourly
Glycerol (Glycerin) 2.5 g suppository 1 suppository rectally as required
Sodium picosulfate 4 mg/5 mL 10-20 mL PO 24 hourly at bedtime
5 mg/5 mL 5-10 mg PO 24 hourly at bedtime
7.5 mg/mL 10-20 drops PO at bedtime
8 mg/tab 1-2 tab PO 24 hourly at bedtime
Standardized senna concentrate 187 mg/tab 2 tab PO 24 hourly, may increase to 4 tab PO 12 hourly
325 mg/cap 2 cap PO 24 hourly at bedtime
374 mg/tab 1-2 tab PO 24 hourly, may increase to 2 tab PO 12 hourly
450 mg/cap 1 cap PO 1 hour after breakfast
Senna alexandrina:
400 mg/cap 		 2-3 cap PO 24 hourly before bedtime 
Sennosides A and B: 7.5 mg/tab  2-4 tab PO 24 hourly at bedtime 
Sennosides A and B: 8.77 mg/tab  2 tab PO 24 hourly. may increase to 4 tab PO 12 hourly 
Sennosides A and B: 17.54 mg/tab  1-2 tab PO 24 hourly, may increase to 2 tab PO 12 hourly 
Sennoside B:
7.5 mg/tab 		 1-4 tab PO 24 hourly at bedtime 
Sennoside B:
16 mg/tab 		 1-2 tab PO 24 hourly 
Osmotically Acting Laxatives
Lactitol monohydrate 10 g/15 mL 15-30 mL PO 24 hourly Adverse Reactions
  • GI effects (abdominal discomfort, flatulence, cramps, nausea/vomiting); Other effects (Na retention, bloating)
  • Prolonged use or excessive dose may cause diarrhea with loss of water and electrolytes
  • Mg-containing products could cause hypermagnesemia
Special Instructions
  • Encourage adequate fluid intake
  • Avoid in patients with intestinal obstruction, bowel perforation, megacolon; Lactitol monohydrate and Lactulose should not be administered to patients with galactosemia
  • Use with caution in patients with impaired renal function, patients on Ca antagonists, diuretics or other drugs that may affect electrolyte levels; colostomy patients; heart disease; pre-existing electrolyte disturbances
Lactulose 3.3 g/5 mL Initial dose: 15-45 mL PO 24 hourly or divided 12 hourly
Maintenance dose:
10-30 mL PO 24 hourly
Max dose: 60 mL/day
3.43 g/5 mL
9.9 g/15 mL
10 g/15 mL
66.7 g/100 mL,
667 g/L,
667 mg/mL
670 mg/mL
Macrogol (Polyethylene glycol) 4,000 powder 10-20 g PO 24 hourly
3,350 powder 17 g PO 24 hourly
Magnesium hydroxide (Mg [OH]2, Milk of Magnesia) 400 mg/5 mL 15-60 mL PO at bedtime or upon arising
800 mg/5 mL 10-30 mL PO 24 hourly at bedtime or in divided doses
8 g/100 mL 30-45 mL PO at bedtime or morning after waking
Monosodium phosphate/Disodium phosphate (Monobasic Na phosphate/Dibasic Na phosphate, Sodium biphosphate/Sodium phosphate)
 Oral solution 20-45 mL PO 24 hourly 
Rectal solution  133 mL (1 bottle) rectally 24 hourly or as directed 
Sodium chloride (NaCl) 15% rectal solution 20-40 mL rectally as required
Sorbitol 5 g/sachet 2 sachets PO at bedtime and 1 sachet PO before breakfast
70% oral solution 30-45 mL (27-40 g) PO 24 hourly 
25-30% rectal solution  120 mL rectally as an enema 24 hourly 
Softeners, Emollient Laxatives1
Docusate sodium 20 mg/5 mL oral liquid

15-60 mL PO 24 hourly or in divided doses

Adverse Reactions

  • Rarely diarrhea, nausea, abdominal cramps; skin rash has occured

Special Instructions

  • Avoid long-term use
  • Do not use when intestinal obstruction or undiagnosed abdominal symptoms are present
50 mg/5 mL oral solution  100 mg PO 8 hourly
Max dose: 500 mg/day in divided doses 
Paraffin (Liquid paraffin) 2.5 mL/5 mL 10-20 mL PO when required before bedtime Adverse Reactions
  • Excessive use of paraffin may cause anal seepage and irritation; foreign-body granulomatous reactions may occur; lipoid pneumonia can occur following aspiration
Special Instructions
  • Avoid if abdominal pain, nausea or vomiting is present
4.83 mL/15 mL oral emulsion  15-30 mL PO when required before bedtime 
Other Drugs for Constipation
Elobixibat 5 mg/tab 10 mg PO 24 hourly
Max dose: 15 mg/day 		Adverse Reactions
  • GI effects (abdominal pain and distension, diarrhea, nausea, abdominal discomfort); Other effects (abnormal liver function test, increased creatine kinase and creatine phosphokinase)
Special Instructions
  • Take on an empty stomach
  • Avoid in patients with known or suspected GI obstruction associated with tumor or hernia
  • Use with caution in elderly and patients with serious hepatic disorder
  • Consider dose reduction, withdrawal or discontinuation if diarrhea or abdominal pain occurs
Lubiprostone 24 mcg/cap 24 mcg PO 12 hourly Adverse Reactions
  • GI effects (nausea/vomiting, diarrhea, abdominal pain and distension, flatulence); Other effects (headache, syncope, hypotension)
Special Instructions
  • Avoid in patients with known or suspected mechanical GI obstruction
  • Use with caution in patients with dyspnea, moderate and severe hepatic impairment
  • Perform a thorough evaluation in patients with symptoms suggestive of mechanical GI obstruction prior to initiating therapy
  • Discontinue treatment if severe diarrhea occurs
1Various combination products are available. Please see the latest MIMS for specific formulations and prescribing information.

Neuromuscular Disorder Drugs

Drug Dosage Remarks
Distigmine
bromide		 Chronic hypotonic constipation:
Initial dose: 2.5 mg PO 24 hourly
May increase in increments of 2.5 mg every 3 days
Max dose: 10 mg/day
Continue treatment until normal intestinal function has been restored (10-14 days) 		Adverse Reactions
  • GI effects (nausea/vomiting, diarrhea, abdominal cramps); Other effects (increased salivation, bronchial secretions, and lacrimation, respiratory failure, rashes, bradycardia, miosis, muscle cramps, weakness)
Special Instructions
  • Avoid in patients with mechanical intestinal or urinary tract obstruction or peritonitis
  • Use with caution in patients with cardiovascular disorders, asthma, recent intestinal or bladder surgery, epilepsy, parkinsonism, PUD, DM, renal impairment
Neostigmine
methylsulfate		 Atonic constipation:
0.5-2.5 mg SC or IM 24 hourly
Pyridostigmine
bromide		 Atonic constipation:
60 mg PO 4 hourly

Other Gastrointestinal Drugs

Drug Dosage Remarks
Linaclotide 72-145 mcg PO 24 hourly Adverse Reactions
  • GI effects (diarrhea, abdominal pain and distension, flatulence)
Special Instructions
  • Take at least 30 minutes prior to first meal of the day
  • Avoid in patients with known or suspected mechanical GI obstruction
  • Discontinue treatment if severe diarrhea occurs

Supplements & Adjuvant Therapy

Drug Dosage Remarks
Bifidobacterium lactis1 BB-12 1 g PO 24 hourly Special Instructions
  • Avoid in patients with allergy to milk and dairy products
  • May have possible reduced effect with antibiotics
Partially hydrolyzed cyamopsis tetragonoloba gum (Partially hydrolyzed guar gum)  6 g PO 24 hourly 

Special Instructions

  • May be taken with or without food
Lactic acid-producing Organisms
Lactobacillus acidophilus2 1-4 cap or tab PO 8-24 hourly or
1-2 sachet PO 8-24 hourly 		Special Instructions
  • Taken on an empty stomach; if GI discomfort occurs, may take with meals
Lactobacillus reuteri 1-2 tab PO 24 hourly or 1-2 sachet PO 24 hourly Special Instructions
  • May be taken with or without food
Lactobacillus sporogenes 4 tab PO 8 hourly or 4 sachets PO 8 hourly Special Instructions
  • Should be taken with food
1Various combination products for Bifidobacterium sp are available. Please see the latest MIMS for specific formulations and prescribing information.
2Various combination products are available. Please see the latest MIMS for specific formulations and prescribing information.

Disclaimer

All dosage recommendations are for non-pregnant and non-breastfeeding women, and non-elderly adults with normal renal and hepatic function unless otherwise stated.  
Not all products are available or approved for above use in all countries.  
Products listed in the Drug Summary are based on indications stated in the locally approved product monographs.   
Please refer to local product monographs in Related MIMS Drugs for country-specific prescribing information.  

Related MIMS Drugs