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Citric acid

Laxative · Bowel Cleansing Agent

Also known as Citric acid anhydrous, Magnesium citrate

LaxativeBowel Cleansing Agent
CDSCO approvedSchedule H
EXCRETION
not curated
INTERACTIONS
4 major
SEVERE in our sources
PREGNANCY
Use with caution.
FDA category + note
Top interactions
  • Aluminum HydroxideSevereDatabaseDDInter
  • BictegravirSevereDatabaseDDInter
  • DolutegravirSevereDatabaseDDInter
  • ErdafitinibSevereDatabaseDDInter

Mechanism

Citric acid reacts with magnesium carbonate upon reconstitution to form magnesium citrate. Magnesium citrate is an osmotic laxative that draws water into the intestinal lumen. This increased fluid volume in the bowel distends it and stimulates peristalsis, leading to bowel evacuation.

Indications

Bowel evacuation for surgeryBowel evacuation for colonoscopyBowel evacuation for radiological examinationBowel cleansing before any procedure requiring a clean bowel

Dosing

Adult
1 sachet, given 8 a.m. the day before the procedure and 1 sachet, given between 2 and 4 p.m. the day before the procedure.
Pediatric
Child 5–9 years: One-third of a sachet to be given at 8 a.m. the day before the procedure and, one-third of a sachet to be given between 2 and 4 p.m. the day before the procedure. Child 10–17 years: 0.5–1 sachet, given at 8 a.m. the day before the procedure and 0.5–1 sachet, given between 2 and 4 p.m.
Renal adjustment
Adults and children: Avoid if eGFR less than 30 mL/minute/1.73 m2—risk of hypermagnesaemia.
Geriatric
Use half the adult dose in frail elderly patients.

Contraindications

  • Acute intestinal or gastric ulceration
  • Acute severe colitis
  • Gastric retention
  • Gastrointestinal obstruction
  • Gastro-intestinal perforation
  • Toxic megacolon

Side effects

Common
Gastrointestinal discomfortNauseaVomiting
Serious
  • Dehydration
  • Dizziness
  • Electrolyte imbalance
  • Headache

Pregnancy & lactation

Pregnancy

Use with caution.

Lactation

Use with caution.

Drug interactions

Aluminum Hydroxide
Severe
Database

Clinical effect not specified

Source: DDInter

Bictegravir
Severe
Database

Drug interaction classified as: absorption

Source: DDInter

Dolutegravir
Severe
Database

Clinical effect not specified

Source: DDInter

Erdafitinib
Severe
Database

Drug interaction classified as: others

Source: DDInter

8 additional low-confidence interactions hidden — those rows lack a documented mechanism or management plan in our sources.

Related guidelines

Other Laxative drugs

Ask House about Citric acid

Continue into a citation-backed clinical answer with the drug context already attached.

Sources: Katzung, BNF, Harriet Lane·Verified: 2026-05-13 · House clinical team