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Sodium lauryl sulfoacetate

Rectal laxative, wetting agent

ATC code: A06AG11

Brand names: Micralax, Microlax

Updated · Methodology

Indications

B

Occasional constipation

Second line

The Micralax micro-enema resolves occasional constipation within 5 to 15 minutes, so it is given just before the planned time of defecation. The AEMPS ficha técnica gives the indication as local symptomatic relief of occasional constipation in adults and adolescents over 12 years, one cannula a day. Children under 12 only at a doctor's decision. The ceiling is 6 consecutive days, and the ficha asks people to stop if blood appears in the stool, if irritation or pain appears, or if the usual bowel habit has not returned. There are no placebo-controlled trials of this combination, which the ficha says openly: the product has a long practice of use rather than a body of randomized data. Water, fibre and movement remain the first step in constipation.

Sources

  1. AEMPS: Ficha técnica de lauril sulfoacetato (2022)

ICD-10: K59.0

Marketing claims without evidence base

The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.

D

Chronic constipation

Not recommended

A micro-enema is convenient, and for some people it therefore moves into the category of daily habits. For chronic constipation that is no solution. The AEMPS ficha técnica limits use to six consecutive days and asks to avoid prolonged use. Regular rectal stimulation changes the defecation reflex: the bowel gets used to firing on an external signal while its own urge weakens. In chronic constipation the cause is looked for first – drugs, the thyroid, diabetes, irritable bowel syndrome, less often colon cancer – and treatment is built on fibre, water, routine and oral osmotic agents. Warning signs that stop self-treatment: blood in the stool, weight loss, a change in bowel habit lasting beyond two weeks, night pain. If a micro-enema was recommended as a permanent daily remedy, consider seeking a second opinion.

Sources

  1. AEMPS: Ficha técnica de lauril sulfoacetato (2022)

ICD-10: K59.0 · ICD-11: ME05.0

D

Hemorrhoidal disease

Not recommended

During a hemorrhoid flare a micro-enema looks like the gentle option, but the AEMPS ficha técnica lists acute hemorrhoidal crisis and hemorrhagic colitis among the contraindications. The cannula mechanically touches the inflamed pile, the lining is already fragile and bleeding increases. The logic of hemorrhoid treatment is different: soften the stool systemically – fibre, water, an oral osmotic laxative – so that defecation does not injure the piles, plus sitz baths and topical products prescribed by a doctor. Rectal bleeding deserves a separate conversation: in some patients the cause is not hemorrhoids, and writing it off to piles without an examination is unsafe. If a micro-enema was advised during a hemorrhoid flare, consider seeking a second opinion.

Sources

  1. AEMPS: Ficha técnica de lauril sulfoacetato (2022)

ICD-10: K64 · ICD-11: DB60

How to read tiers A–F
  • AStrong evidence – first or second line in international guidelines
  • BRecommended in selected cases
  • CStudy data contradict each other
  • DBenefit not proven, no documented harm
  • FDocumented harm, or risk without benefit

Mechanism of action

Sodium lauryl sulfoacetate is a surfactant. In the rectum it wets hard stool: water that was previously bound redistributes into the mass and softens it. In the Micralax micro-enema the substance comes with sodium citrate, which works osmotically – drawing water into the lumen and holding it there. Together they produce an effect within 5 to 15 minutes, which is why the micro-enema is given just before the desired time of defecation. Systemic absorption with correct use is limited, and the AEMPS ficha técnica expects no meaningful effects beyond the rectum. There are no placebo-controlled trials of the combination, which the ficha states outright, and the adverse reactions come from post-marketing surveillance.

Safety

Contraindications

  • Hypersensitivity to the active substances
  • Acute hemorrhoidal crisis
  • Hemorrhagic colitis
  • Children under 12 years without a doctor's prescription

Serious adverse effects

  • Hypersensitivity reactions
  • Injury to the rectal lining from careless insertion of the cannula

Common adverse effects

  • Burning and discomfort in the anal area
  • Urge to defecate
  • Abdominal pain

Pregnancy: can you take Sodium lauryl sulfoacetate?

There are no adequate controlled studies in pregnant women. With correct use systemic absorption is limited and no undesirable effects are expected during pregnancy.

Breastfeeding: can you take Sodium lauryl sulfoacetate?

Whether sodium citrate and sodium lauryl sulfoacetate pass into breast milk is unknown, but systemic absorption with correct use is limited.

Calculate RID

Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.

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Frequently asked

What is Sodium lauryl sulfoacetate used for?

Sodium lauryl sulfoacetate is evaluated for the following indications with varying evidence strength: Occasional constipation (evidence tier B), Hemorrhoidal disease (evidence tier D), Chronic constipation (evidence tier D). See the full indication matrix with dosing and citations above on this page.

What are the side effects of Sodium lauryl sulfoacetate?

Common side effects of Sodium lauryl sulfoacetate (≥ 1 in 100): Burning and discomfort in the anal area, Urge to defecate, Abdominal pain. See the Safety section for uncommon and serious reactions.

Is Sodium lauryl sulfoacetate safe during pregnancy?

There are no adequate controlled studies in pregnant women. With correct use systemic absorption is limited and no undesirable effects are expected during pregnancy.

Is Sodium lauryl sulfoacetate compatible with breastfeeding?

Whether sodium citrate and sodium lauryl sulfoacetate pass into breast milk is unknown, but systemic absorption with correct use is limited.

Who should not take Sodium lauryl sulfoacetate?

Sodium lauryl sulfoacetate is contraindicated in: Hypersensitivity to the active substances; Acute hemorrhoidal crisis; Hemorrhagic colitis; Children under 12 years without a doctor's prescription. Full list in the Safety section.

Other drugs in this group

Bisacodyl, Glycerol, Inulin (chicory/agave/Jerusalem artichoke prebiotic), Psyllium (Plantago ovata, ispaghula husk), Sodium picosulfate