Laxative and Cathartic Use During Breastfeeding

Laxatives

Docusate is a mild laxative and stool softener with a slow onset of action of 1–3 days. It is minimally absorbed from the gastrointestinal (GI) tract and, therefore, is unlikely to be found in the maternal serum or breast milk. Docusate is considered acceptable to use in nursing mothers, although laxatives that are completely unabsorbed may be preferred. Docusate is a detergent and should not be used with mineral oil because it can enhance the absorption of mineral oil, which can be found in milk in trace amounts.

Magnesium hydroxide (milk of magnesia) is a mild osmotic saline laxative. No measurements of magnesium in breast milk have been made after oral ingestion of magnesium hydroxide by nursing mothers. However, even intravenous magnesium sulfate increases the milk magnesium concentration only slightly. In a study of mothers who were in their first day postpartum, each received an oral dose of magnesium equivalent to 900 mg of magnesium hydroxide. Additional doses were given on subsequent days if needed. None of the breastfed infants were noted to have any markedly abnormal stools, but all of the infants also received supplemental feedings.

Hydrocolloids increase the bulk of feces and act as mild laxatives with an onset of 1–3 days. They are not absorbed from the GI tract so cannot enter the milk. Two of these products, psyllium and flaxseed, are good choices for nursing mothers. Patients should avoid repeated exposure to airborne psyllium powder because allergic sensitization can occur. Symptoms include rhinitis, conjunctivitis, wheezing, asthma, and urticarial rashes. Severe anaphylactic reactions have been reported in individuals with occupational exposure who then ingest psyllium products. Polycarbophil calcium is a synthetic hydrocolloid laxative. No reports of its use during breastfeeding exist, but like the others, it is not absorbed from the maternal GI tract.

Aloe vera gel consists of the clear gel from the center of fresh leaves of Aloe vera and related aloes. Active ingredients include mono- and polysaccharides (e.g., acemannan and glucomannan) that act as hydrocolloids, as well as allantoin, enzymes (e.g., cyclooxygenase, amylase, lipase, alkaline phosphatase, and carboxypeptidase), and salicylic acid. Aloe vera gel is a mild laxative, but it should not be confused with aloe latex that comes from the inner portion of the aloe skin containing potent anthraquinone cathartics. Aloe latex should not be used during breastfeeding.

Because mineral oil is poorly absorbed orally, little or none will reach the GI tract of the infant or cause any adverse effects in breastfed infants. One study supports the lack of effect of maternal mineral oil on the bowels of their breastfed infants. In one older study, mothers who were in the first day postpartum received 15 mL of mineral oil, with additional doses given daily as needed. None of their breastfed infants had any markedly abnormal stools, although none of the infants were exclusively breastfed. Repeated maternal use of mineral oil should be avoided because it can cause a deficiency of fat-soluble vitamins by binding them in the maternal GI tract. As noted previously, mineral oil should not be used with docusate.

Most osmotic laxatives are sugar alcohols, such as lactitol, lactulose, and sorbitol. Although these drugs are thought to be unabsorbed and, therefore, not affect the infant, they can be fermented in the GI tract. These are among the group of products called “fermentable oligo-, di-, and monosaccharides and polyols” or FODMAPs. Some preliminary studies indicate that their repeated intake by nursing mothers can cause symptoms of colic in their infants.^1,2 Although these products are unlikely to cause diarrhea in infants with occasional use, repeated use might increase the risk for symptoms of colic.

Cathartics

Cathartics are stronger intestinal stimulants than laxatives. Senna is popular for postpartum use. It comes from the fruit pod or leaf of the plant Senna alexandrina and contains sennosides, which are metabolized by gut bacteria to the active rhein monoanthrones. Studies that measured sennosides in milk have generally not detected them, but rhein was measured in milk during the 26 hours after the last dose in one study. Peak rhein milk levels generally occurred 10 hours after the dose. The authors estimated that breastfed infants would have received at most 500 ng/kg of rhein. An early uncontrolled report using 3.6 mL of senna fluid extract on day 5 postpartum found that a laxative effect on the bowels was observed in 6 of 10 infants. In a randomized nonblinded study, 35 mothers were given tablets containing a total of 14 mg of standardized senna extract once daily for 2 weeks starting in the immediate postpartum period. Six of the 37 breastfed infants were reported to have diarrhea, which was a higher percentage than with nonabsorbable laxatives used as controls in the study. However, two observational studies and a randomized double-blind study found no increased frequency of diarrhea in breastfed infants after maternal use of senna in modern commercial products. Standardized doses of senna found in commercially available drug products are acceptable to use during breastfeeding. Maternal use of high doses of these products or use of crude plant products might result in loose stools or diarrhea in breastfed infants.

Bisacodyl is a prodrug metabolized to the active drug, bis-(p-hydroxyphenyl)-2-pyridyl-2-methane (BHPM). In one study, 16 postpartum women who were not breastfeeding, but were producing at least 200 mL of milk daily by breast pump, were given enteric-coated bisacodyl tablets 10 mg/day orally for 7 days. All breast milk was collected daily from the day before drug administration until 2 days after the last dose. Free and conjugated BHPM were undetectable (<1 mcg/L) in all milk samples. Bisacodyl can be taken during breastfeeding and no special precautions are required.

Cascara (Frangula purshiana, Rhamnus purshiana) contains potent anthraquinone cathartics as well as other laxative components. Cascara was removed from over-the-counter laxatives by the Food and Drug Administration in 2002, but it is still available as a dietary supplement. After administration of 65 mg of cascara as a fluid extract, cascara was qualitatively detected in the breast milk of 5 of 10 women collected for 20 hours. In an observational case series, no cases of diarrhea were observed among the breastfed infants of 142 mothers who received 400 mg of cascara extract on day 3 postpartum. This negative result might have been because of the low volume of colostrum received by the infants of this age. In two uncontrolled studies, a total of 10 of 22 breastfed neonates appeared to have loose stools after administration of 65 mg of cascara fluid extract to their mothers. Cascara should probably be avoided during breastfeeding.

Castor (Ricinus communis) beans contain triglycerides, mostly consisting of ricinoleic acid esters, and small amounts of the toxic ricin and ricine. Pressing of the beans produces castor oil and purification of the oil eliminates the ricin and ricine. Castor oil is a strong stimulant cathartic. No data exist on the excretion of any components of castor oil into breast milk after oral ingestion or on their safety and efficacy in nursing mothers or infants. However, little of the active ricinoleic acid is thought to be absorbed from the intestine. Because of a lack of information, other cathartics may be preferred in nursing mothers.

Colonoscopy Bowel Preparation

The standard product for bowel cleansing is a large volume of polyethylene glycol solution with electrolytes added to avoid electrolyte depletion. No published experience exists with polyethylene glycol during breastfeeding. The drug is only about 0.2% absorbed from the GI tract, so it is not expected to enter the breast milk in clinically relevant amounts.

Sodium picosulfate is also used for preprocedure bowel cleansing. Picosulfate is not absorbed from the GI tract, and its active metabolite, which is the same as bisacodyl's, is not detectable in breast milk. Sodium picosulfate can be used during breastfeeding and no special precautions are required.

Newer products for bowel preparation use osmotic saline cathartics, such as magnesium, phosphate, or sulfate, and lower volumes of liquid. Phosphate is a normal constituent of breast milk and infants normally receive ∼130 mg of inorganic phosphate daily from breast milk. Administration of 30 g of oral sodium phosphate solution approximately doubles the maternal serum phosphate concentration, with serum concentrations returning to baseline ∼24 hours after the dose. Assuming breast milk phosphate concentration also doubles, the increased phosphate dose to the infant would be only 130 mg for 1 day. Administration of a phosphate enema containing a total of 14 g of sodium phosphate dibasic and 38 g of sodium phosphate monobasic to 33 subjects increased serum phosphate by an average of ∼25%. In another patient, a phosphate enema containing a total of 7.2 g of sodium phosphate dibasic and 19.2 g of sodium phosphate monobasic increased serum phosphate by 35% after a single dose. Use of a phosphate rectal enema by a nursing mother would require no special precautions. It is probably not necessary to suspend breastfeeding after the use of oral sodium phosphate solutions given once or twice for bowel evacuation before a procedure.

Another new osmotic cathartic preparation in tablet form for bowel cleansing contains sodium sulfate, magnesium sulfate, and potassium chloride. Magnesium and sulfate, the cathartic components, are poorly absorbed orally and would not increase magnesium or sulfate levels in breast milk.

Conclusions

Most modern laxatives do not pose a risk to mothers or infants. Bulk-forming laxatives and stool softeners are preferred for prevention of constipation. Osmotic cathartics, bisacodyl and senna, are good choices for treating constipation. Some plant-based cathartics contain potent anthraquinones that can affect the breastfed infant. Minimizing the use of opioids postpartum can also minimize the need for cathartics.