Lower GI active agents


Benefits: Extremely effective at treating diarrhea and cramps from a wide variety of causes from dietary indiscretion to viral and other intestinal problems. 

Cautions: Can cause constipation. Avoid in toxin-producing and antibiotic-associated diarrheas.

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Bismuth subsalicylate

See review under upper GI section. 

Peppermint oil

Benefits: Helpful in patients with irritable bowel syndrome. Treats cramping and diarrhea. Has lower number needed to treat than many prescription agents.4

Cautions: It is a smooth muscle relaxant, so it can worsen GERD by decreasing LES pressures.

Fiber supplements

Benefits: Gentle laxative effects. May help with both constipation and diarrhea symptoms. Psyllium also has other metabolic benefits such as lowering blood sugar and LDL cholesterol levels, and if taken before meals it can promote satiety and help with weight loss.

Cautions: May cause gas and bloating, especially if introduced too rapidly or not taken with sufficient quantities of water.


Benefits: A wide array of benefits have been reported and may be strain specific. Improvements in constipation and irritable bowel syndrome are frequently reported benefits.

Cautions: May cause loose stool, a theoretical concern in severely immunocompromised patients.

Aloe vera gel

Benefits: Used as a laxative. Increases peristalsis and decreases reabsorption of water. Less well-documented uses include treatment of stomach ulcers, ulcerative colitis, and hemorrhoids.

Cautions: Aloe gel products with the International Aloe Association seal saying they are 99.9% aloin-free would be advised over aloe latex products, which may have more toxicity. Some components of aloe vera may be carcinogenic and have been reported to cause renal disease and renal failure. 

TABLE 2. Selected agents for lower GI problems

  • Imodium
  • generics
Bismuth subsalicylate
  • Pepto-Bismol
  • Kaopectate
  • generics
Peppermint oil
  • liquid
  • capsules
Fiber supplements
  • psyllium (Metamucil, Konsyl)
  • methylcellulose (Citrucel)
Probiotics (various single
and multistrain products)
  • Align
  • VSL#3
  • many others
Aloe vera gel
  • No specific brands identified

Knowledge of how to use OTC, supplemental, and herbal products for upper and lower GI problems can alleviate many symptoms that for generations lowered the quality of life for individuals with GI issues. Teaching patients how to properly use these agents can be a step toward empowering them to take control of their own health. The clinician who has a broad understanding of the large number of products that are available can aid patients in the selection of agents to treat their symptoms and do so in a way that is both safe and cost effective.

Chad D. Rasmussen, APRN, CNP, is nurse practitioner critical care fellowship director at the Department of Family Medicine at the Mayo Clinic in Rochester, Minn.


  1. Lam JR, Schneider JL, Zhao W, Corley DA. Proton pump inhibitor and histamine 2 receptor antagonist use and vitamin B12 deficiency. JAMA. 2013;310(22):2435-2442. 

  2. Ghochae A, Fshar MH, Amin G, et al. The survey of the effect of ginger extract on gastric residual volume in mechanically ventilated patients hospitalized in the Intensive Care Units. Advances Environ Biol. 2013;7(11):3395-3400.

  3. Kandil TS, Mousa AA, El-Gendy AA, Abbas AM. The potential therapeutic effect of melatonin in Gastro-Esophageal Reflux Disease. BMC Gastroenterol. 2010;10:7.

  4. Grigoleit HG, Grigoleit P. Peppermint oil in irritable bowel syndrome. Phytomedicine. 2005;12(8):601-606.