Laxative Abuse– Causes, Symptoms, Diagnosis, Treatment and Ongoing care
Laxative abuse, which may be intentional or unintentional, is a clinically important cause of chronic diarrhea. It manifests commonly as watery diarrhea caused by self-medication or as apparent diarrhea caused by adding various fluids to stool.
- System(s) affected: GI; Nervous; Psychiatric
- Synonym(s): Factitious diarrhea; Cathartic colon
- Predominant age: 18–40 years with bulimia or anorexia nervosa; 40–60 years without eating disorders
- Predominant sex: Female (90%) > Male
- Children may be given excess laxation by their caregivers (especially mothers), an example of Munchausen syndrome by proxy.
Laxative abuse in different groups:
- Unexplained chronic diarrhea after routine investigations: 3.5–7%
- Patients with binging/purging anorexia and bulimia nervosa: As many as 70%
- Referrals to tertiary-care centers for evaluation of chronic diarrhea: As high as 15%
- Elderly in nursing homes at increased risk
In patients with eating disorders:
- Longer duration of illness
- Comorbid psychiatric diagnoses (e.g., major depression, obsessive–compulsive disorder, posttraumatic stress disorder, anxiety, borderline personality disorder)
- Earlier appearance of eating disorder symptoms
- Educate patients about normal bowel function, potential adverse effects of excessive laxation, and use of additional medications (e.g., magnesium-containing antacids) that can cause diarrhea.
- Ask patients specifically about laxative use.
- Chronic ingestion of any laxative agent
- Osmotic diarrhea: Magnesium sulfate, nonabsorbable sugars, sodium phosphate
- Secretory diarrhea: Dihydroxy bile salts, castor oil, docusate sodium
- Psychologic factors:
- Bulimia or anorexia nervosa
- Secondary gain of attention
- Hysterical behavior
- Inappropriate perceptions of “normal” bowel habits
- Chronic constipation, especially in the elderly
Commonly Associated Conditions
- Anorexia nervosa
- Bulimia nervosa
- Depression and anxiety
- Borderline personality
- Self-injurious behaviors/suicidal ideation
- Impulsive behavior
- Münchausen syndrome/Münchausen syndrome by proxy
Chronic diarrhea can be characterized into four types: secretory, osmotic, inflammatory, and fatty diarrhea. Be sure to rule out other causes of chronic diarrhea even if laxative abuse is high on the differential.
- Suspicion in patients with undiagnosed chronic diarrhea, especially when refractory; some patients may not be aware of the association of these over-the-counter medications with chronic diarrhea.
- Signs and symptoms: Increasing frequency of bowel movements; large volume, watery diarrhea; nocturnal bowel movements that are typically absent in osmotic diarrhea or in irritable bowel syndrome
- Additional symptoms: Abdominal pain, rectal pain, nausea, vomiting, weight loss, malaise, muscle weakness
- Additional signs: Hypokalemia, hyperphosphatemia, hypernatremia, skin pigmentation, finger clubbing, cyclic edema, kidney stones, melanosis coli, cardiac arrhythmias with severe hypokalemia
- Monitor “doctor hopping.”
- No specific findings in most cases but may include cachexia, evidence of dehydration, abdominal pain or distension, and edema.
- Rarely, severe cases may be associated with renal failure, cardiac arrhythmias, or skeletal muscle paralysis.
Diagnostic Tests & Interpretation
- Serum chemistries: Hypokalemia, metabolic alkalosis (1)[C]
- Urinalysis: bisacodyl, senna, cascara, magnesium, and phosphate titers
- Urine volume and electrolytes (help assess volume status and need for hospitalization).
- Stool sodium, potassium (see algorithm below)
- Stool pH (alkalinization suggests presence of phenolphthalein)
- Stool for laxative titers (bisacodyl, senna, cascara, magnesium, phosphate, castor oil, mineral oil)
Initial lab tests
- Serum electrolytes will show hypokalemia secondary to increased intestinal fluid loss.
- Acute diarrhea: Metabolic acidosis due to hypovolemia
- Chronic diarrhea: Metabolic alkalosis secondary to hypokalemia-induced inhibition of chloride uptake in the intestine, thereby inhibiting bicarbonate secretion
- Complete blood count and stool cultures: Rule out infectious cause if history is suspicious.
Follow-Up & Special Considerations
If history and initial lab tests are suspicious for laxative abuse, the following algorithm can be used to confirm diagnosis and determine what type of laxative is being used.
- Collect 24-hour stool: If solid, workup is over.
- Calculate stool osmolality, stool electrolytes, and osmolal gap (= 290 – 2(Na+ + K+), where Na+ and K+ are the concentrations from the stool sample.)
- If osmolality >400 mosm/kg, rule out urine contamination of stool Measure urea and creatinine of sample.
- If osmolality <250–400 mosm/kg, rule out water added to stool (colon cannot dilute stool to osmolality plasma).
- If osmolality = 250–400 mosm/kg, measure osmolal gap.
- Gap >50: Unmeasured solute; check fecal fat and stool magnesium levels.
- Gap <50: Rule out use of secretory laxative; urinalysis and stool analysis for laxative titers. Do not obtain serum laxative titers as they peak 1–2 hours after ingestion. Urine titers can be 10 × as high as plasma titers.
- Thin-layer chromatography may produce false-positive tests for bisacodyl and false-negative tests for senna (2)[C].
Not usually necessary for the diagnosis of laxative abuse; colonoscopy, small-bowel endoscopy, or imaging studies may be needed to evaluate other causes of chronic diarrhea. These tests may be helpful for understanding the chronicity of laxative abuse. Be cautious about perpetuating Munchausen syndrome through extensive workup.
- Melanosis coli: Dark brown discoloration of colon with lymph patches visible through mucosa; also can be diagnosed by demonstrating pigment-containing macrophages in lamina propria; only occurs with abuse of anthraquinone-containing laxatives
- Cathartic colon: Refers to dilatation and ahaustral appearance on barium enema or plain film; result of severe and prolonged laxative abuse
Any etiology of chronic diarrhea, especially in high-risk groups
- Replace needed vitamins, electrolytes, and minerals.
- Nonstimulant laxatives if needed to treat constipation (3)[C]:
- Senna best during pregnancy and lactation
- Avoid danthron owing to hepatotoxicity.
- Precautions: Patients may be manipulative in attempts to deny problem; may hide laxatives in hospital rooms.
- Significant possible interactions:
- Increased rate of intestinal motility may affect rate of absorption of medications (e.g., antibiotics, hormones).
- Docusate sodium may potentiate hepatotoxicity of other drugs.
- Psychological support is essential (3)[C].
- Confront the patient gently with support and understanding.
- Wean patient off laxatives, and substitute high-fiber diet and bulk preparations or short-term saline enemas (3)[C].
- Treat constipation.
- Treat metabolic abnormalities with potassium supplements, etc. (oral preferred) (3)[C].
Avoid exploratory surgery and repetitive evaluations with invasive procedures.
- Persistent diarrhea with evidence of hemodynamic instability
- Electrolyte/metabolic complications, including lactic acidosis
- Cardiac arrhythmias
- Inability to contract for safety
Resucitate based on clinical picture. If patient is hemodynamically stable and without significant abnormalities in serum sodium, can give normal saline boluses or PO replacement to correct metabolic alkalosis (chronic) or acidosis (acute) as needed. If patient is hemodynamically unstable, treat volume status as in a hypovolemic shock, while monitoring serum electrolytes closely (especially sodium, potassium, and bicarbonate).
If stable, patient does not need continuous telemetry. However, depending on psychiatric history, patient may need constant observation. Special care must be taken to ensure adequate nutrition while in-house and to discard any laxatives from patient possessions. If patient is unstable, telemetry and appropriate vital-signs monitoring may be necessary.
- Psychological support
- Diet and bowel programs
- Careful psychological counseling
- Careful medical support; show concern by frequent visits as needed.
- Assess serum electrolytes.
Ensure good nutritional habits.
- Increase fiber intake.
- Adequate calories, especially with bulimia
- Protracted course
- Prognosis related to psychological response
- Prognosis poor with anorexia nervosa
- Risk of multiple tests, procedures, and surgeries
- Electrolyte imbalances (hypokalemia)
- Renal failure
- Fatalities, especially in children given laxatives by parents
- Renal calculi
- No convincing evidence that chronic use of stimulant laxatives causes functional or structural impairment of colon
- Fecal impaction in elderly
1. Thomas PD, Forbes A, Green J, et al. Guidelines for the investigation of chronic diarrhoea, 2nd edition. Gut. 2003;52(Suppl 5):v1–15.
2. Shelton JH, Santa Ana CA, Thompson DR, et al. Factitious Diarrhea Induced by Stimulant Laxatives: Accuracy of Diagnosis by a Clinical Reference Laboratory Using Thin Layer Chromatography. Clin Chem.2006.
3. National Collaborating Center for Mental Health. Eating disorders: Core interventions in the treatment and management of anorexia nervosa, bulimia nervosa and related eating disorders. Leicester (UK): British Psychological Society; 2004.
Kovacs D, Palmer RL. The associations between laxative abuse and other symptoms among adults with anorexia nervosa. Int J Eat Disord. 2004;36:224–8.
Roerig JL, Steffen KJ, Mitchell JE, Zunker C et al. Laxative abuse: epidemiology, diagnosis and management. Drugs. 2010;70:1487–503.
Xing JH, Soffer EE. Adverse effects of laxatives. Dis Colon Rectum. 2001;44:1201–9.
See Also (Topic, Algorithm, Electronic Media Element)
Algorithm: Diarrhea, Chronic
305.90 Other, mixed, or unspecified drug abuse, unspecified use
280982009 abuse of laxatives (disorder)
- Laxative abuse may be intentional or unintentional; it is a common feature of eating disorders and has a female predilection.
- Consider the diagnosis in adolescents with suggestive symptoms.
- As many as 15% of patients referred to tertiary-care centers for unexplained chronic diarrhea abuse laxatives.
- Presentation is diverse and may be nonspecific, including weight loss, weakness, and hypotension without acknowledgment of diarrhea.
- Consider the diagnosis in patients with watery diarrhea, especially when unexplained or refractory.