What is it?
Senna contains many chemicals called sennosides. Sennosides irritate the lining of the bowel, which causes a laxative effect.
Senna is an FDA-approved over-the-counter (OTC) laxative. It is used to treat constipation and also to clear the bowel before procedures such as colonoscopy. People also use senna for irritable bowel syndrome (IBS), hemorrhoids, weight loss, and many other conditions, but there is no good scientific evidence to support these uses.
How effective is it?
Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.
The effectiveness ratings for SENNA are as follows:
Likely effective for...
- Constipation. Senna is an FDA-approved nonprescription (OTC) drug for adults and children ages 2 years and older. It should be taken at bedtime and tends to work within 6-12 hours. It might cause stomach upset and diarrhea. Senna should not be used for more than 1 week without the supervision of a healthcare provider.
Possibly effective for...
- Emptying the colon before a colonoscopy. Taking senna by mouth might help empty the colon before a colonoscopy. Prior to a colonoscopy, your doctor will recommend a specific regimen to use in order to ensure that your colon is empty prior to the procedure.
Is it safe?
Senna is possibly unsafe when used for longer than 1 week or in doses above 34.4 mg sennosides twice daily. Long-term use can cause the bowels to stop functioning normally and might cause dependence on laxatives. Long-term use can also cause liver damage and other harmful effects.
Special precautions & warnings:
Pregnancy: Senna is possibly safe when taken by mouth during pregnancy for up to 1 week. It is possibly unsafe when taken by mouth for longer than 1 week or in high doses. This has been linked to serious side effects including laxative dependence and liver damage.Breast-feeding: Senna is possibly safe when taken by mouth during breast-feeding for up to 1 week. Small amounts of senna cross into breast milk, but it doesn't seem to be a problem for nursing babies. As long as senna is used in recommended amounts, it doesn't cause changes in the babies' stools.
Children: Senna is likely safe for children over age 2 when taken by mouth for up to 1 week. It is an FDA-approved nonprescription (OTC) medicine that can cause some side effects including stomach discomfort, cramps, and diarrhea. Senna is possibly unsafe when taken by mouth for longer than 1 week or in high doses. Children ages 2-5 shouldn't take more than 8.6 mg sennosides twice daily. Children ages 6-11 shouldn't take more than 17.2 mg sennosides twice daily. Children 12 years and older shouldn't take more than 34.4 mg sennosides twice daily.
Gastrointestinal (GI) conditions: Senna should not be used by people with stomach pain, intestinal blockage, inflammatory bowel disease, diarrhea, appendicitis, stomach inflammation, or hemorrhoids.
Are there interactions with medications?
- Digoxin (Lanoxin)
- Senna is a type of laxative called a stimulant laxative. Stimulant laxatives can decrease potassium levels in the body. Low potassium levels can increase the risk of side effects from digoxin.
- Estrogens
- Taking senna might decrease the effects of estrogen. Senna can reduce the amount of estrogen in the body and how much estrogen the body absorbs.
- Warfarin (Coumadin)
- Senna can work as a laxative. In some people, senna can cause diarrhea. Diarrhea can increase the effects of warfarin and increase the risk of bleeding. If you take warfarin, do not take excessive amounts of senna.
- Water pills (Diuretic drugs)
- Senna is a laxative. Some laxatives can cause diarrhea and decrease potassium levels. "Water pills" can also decrease potassium levels. Taking senna along with "water pills" might make potassium levels drop too low.
Are there interactions with herbs and supplements?
- Horsetail
- Using senna along with horsetail might cause potassium levels to drop too low.
- Licorice
- Using senna along with licorice might cause potassium levels to drop too low.
- Stimulant laxative herbs
- Senna is a type of laxative called a stimulant laxative. Stimulant laxatives can cause diarrhea and decrease potassium levels. Taking senna with other supplements with similar effects might cause more diarrhea and very low potassium levels. Examples of supplements with this effect include aloe, buckthorn, gossypol, and rhubarb.
Are there interactions with foods?
- There are no known interactions with foods.
How is it typically used?
Other names
Methodology
To learn more about how this article was written, please see the Natural Medicines Comprehensive Database methodology.
References
- Tian H, Fan Y, Yang L, et al. The Efficacy of Senna Bowel Preparation for Colonoscopy: A Systematic Review and Meta-analysis. Gastroenterol Nurs 2022;45:428-439. View abstract.
- Chang L, Chey WD, Imdad A, et al. American Gastroenterological Association-American College of Gastroenterology Clinical Practice Guideline: Pharmacological Management of Chronic Idiopathic Constipation. Gastroenterology 2023;164:1086-1106. View abstract.
- Morishita D, Tomita T, Mori S, et al. Senna Versus Magnesium Oxide for the Treatment of Chronic Constipation: A Randomized, Placebo-Controlled Trial. Am J Gastroenterol 2021;116:152-161. View abstract.
- Irazábal B, Sánchez de Vicente J, Galán C, et al. Anaphylaxis Due to Senna (Cassia angustifolia). J Investig Allergol Clin Immunol 2021;31:71-73. View abstract.
- Haoudar A, Chekhlabi N, El Kettani C, Dini N. Acute Hepatitis and Pancytopenia in a Child With Chronic Abuse of Senna. Cureus 2021;13:e12436. View abstract.
- Coskun Y, Yuksel I. Polyethylene glycol versus split high-dose senna for bowel preparation: A comparative prospective randomized study. J Gastroenterol Hepatol 2020;35:1923-1929. View abstract.
- Cogley K, Echevarria A, Correa C, De la Torre-Mondragón L. Contact Burn with Blister Formation in Children Treated with Sennosides. Pediatr Dermatol 2017;34:e85-e88. View abstract.
- Vilanova-Sanchez A, Gasior AC, Toocheck N, et al. Are Senna based laxatives safe when used as long term treatment for constipation in children? J Pediatr Surg 2018;53:722-7. View abstract.
- Chen HB, Lian-Xiang P, Yue H, et al. Randomized controlled trial of 3 days fasting and oral senna, combined with mannitol and simethicone, before capsule endoscopy. Medicine (Baltimore) 2017;96:e8322. View abstract.
- Senokot Package Labeling, Purdue Products, L.P. 2016
- Poyrazoglu OK, Yalniz M. Two low-dose bowel-cleansing regimens: efficacy and safety of senna and sodium phosphorus solution for colonoscopy. Patient Prefer Adherence 2015;9:1325-31.View abstract.
- Yenidogan E, Okan I, Kayaoglu HA, et al. Same-day colonoscopy preparation with Senna alkaloids and bisacodyl tablets: a pilot study. World J Gastroenterol 2014;20:15382-6.View abstract.
- Feudtner C, Freedman J, Kang T, Womer JW, Dai D, Faerber J. Comparative effectiveness of senna to prevent problematic constipation in pediatric oncology patients receiving opioids: a multicenter study of clinically detailed administrative data. J Pain Symptom Manage 2014;48:272-80.View abstract.
- National Toxicology Program. Toxicology study of senna (CAS No. 8013-11-4) in C57BL/6NTAC mice and toxicology and carcinogenesis study of senna in genetically modified C3B6.129F1/Tac-Trp53tm1Brd haploinsufficient mice (feed studies). Natl Toxicol Program Genet Modif Model Rep 2012;:1-114.View abstract.
- Unal, S., Dogan, U. B., Ozturk, Z., and Cindoruk, M. A randomized prospective trial comparing 45 and 90-ml oral sodium phosphate with X-Prep in the preparation of patients for colonoscopy. Acta Gastroenterol.Belg. 1998;61:281-284. View abstract.
- van Gorkom, B. A., Karrenbeld, A., Limburg, A. J., and Kleibeuker, J. H. The effect of sennosides on colonic mucosal histology and bowel preparation. Z.Gastroenterol. 1998;36:13-18. View abstract.
- Lewis, S. J., Oakey, R. E., and Heaton, K. W. Intestinal absorption of oestrogen: the effect of altering transit-time. Eur.J Gastroenterol.Hepatol. 1998;10:33-39. View abstract.
- Agra, Y., Sacristan, A., Gonzalez, M., Ferrari, M., Portugues, A., and Calvo, M. J. Efficacy of senna versus lactulose in terminal cancer patients treated with opioids. J Pain Symptom.Manage. 1998;15:1-7. View abstract.
- Lewis, S. J., Heaton, K. W., Oakey, R. E., and McGarrigle, H. H. Lower serum oestrogen concentrations associated with faster intestinal transit. Br.J Cancer 1997;76:395-400. View abstract.
- Sykes, N. P. A volunteer model for the comparison of laxatives in opioid-related constipation. J Pain Symptom.Manage. 1996;11:363-369. View abstract.
- Maddi, V. I. Regulation of bowel function by a laxative/stool softener preparation in aged nursing home patients. J Am Geriatr.Soc. 1979;27:464-468. View abstract.
- Corman, M. L. Management of postoperative constipation in anorectal surgery. Dis.Colon Rectum 1979;22:149-151. View abstract.
- Fernandez, Seara J., Pascual, Rubin P., Pato Rodriguez, M. A., Pereira Jorge, J. A., Dominguez Alvarez, L. M., Landeiro, Aller E., Tesouro, Rodriguez, I, Gonzalez Simon, M. C., Mendez Veloso, M. C., and Pena, Perez L. [Comparative study of the efficacy and tolerance of 2 types of colon cleansing]. Rev.Esp.Enferm.Dig. 1995;87:785-791. View abstract.
- de Witte, P. Metabolism and pharmacokinetics of anthranoids. Pharmacology 1993;47 Suppl 1:86-97. View abstract.
- Kaspi, T., Royds, R. B., and Turner, P. Qualitative determination of senna in urine. Lancet 5-27-1978;1:1162. View abstract.
- Kobashi, K., Nishimura, T., Kusaka, M., Hattori, M., and Namba, T. Metabolism of sennosides by human intestinal bacteria. Planta Med 1980;40:225-236. View abstract.
- Malmquist, J., Ericsson, B., Hulten-Nosslin, M. B., Jeppsson, J. O., and Ljungberg, O. Finger clubbing and aspartylglucosamine excretion in a laxative-abusing patient. Postgrad.Med J 1980;56:862-864. View abstract.
- Gould, S. R. and Williams, C. B. Castor oil or senna preparation before colonoscopy for inactive chronic ulcerative colitis. Gastrointest.Endosc. 1982;28:6-8. View abstract.
- Brouwers, J. R., van Ouwerkerk, W. P., de Boer, S. M., and Thoman, L. A controlled trial of senna preparations and other laxatives used for bowel cleansing prior to radiological examination. Pharmacology 1980;20 Suppl 1:58-64. View abstract.
- Pers, M. and Pers, B. A crossover comparative study with two bulk laxatives. J Int.Med Res 1983;11:51-53. View abstract.
- Levine, D., Goode, A. W., and Wingate, D. L. Purgative abuse associated with reversible cachexia, hypogammaglobulinaemia, and finger clubbing. Lancet 4-25-1981;1:919-920. View abstract.
- Greiner, A. C. and Warwick, W. E. The use of sennosides A and B in the treatment of constipation in a mental institution. Appl.Ther 1965;7:1096-1098. View abstract.
- Glatzel, H. [Results of long-term therapy of 1059 babitually constipated patients using a standardized senna preparation]. Z.Allgemeinmed. 5-10-1972;48:654-656. View abstract.
- Sanders, R. C. and Wright, F. W. Colonic preparation: a controlled trial of Dulcodos, Dulcolax and Senokot DX. Br.J Radiol. 1970;43:245-247. View abstract.
- Slanger, A. Comparative study of a standardized senna liquid and castor oil in preparing patients for radiographic examination of the colon. Dis.Colon Rectum 1979;22:356-359. View abstract.
- Connolly, P., Hughes, I. W., and Ryan, G. Comparison of "Duphalac" and "irritant" laxatives during and after treatment of chronic constipation: a preliminary study. Curr Med Res Opin. 1974;2:620-625. View abstract.
- Greenhalf, J. O. and Leonard, H. S. Laxatives in the treatment of constipation in pregnant and breast-feeding mothers. Practitioner 1973;210:259-263. View abstract.
- Pockros, P. J. and Foroozan, P. Golytely lavage versus a standard colonoscopy preparation. Effect on normal colonic mucosal histology. Gastroenterology 1985;88:545-548. View abstract.
- van der Jagt, E. J., Thijn, C. J., and Taverne, P. P. Colon cleansing prior to roentgenologic examination. A double blind comparative study. J Belge Radiol. 1986;69:167-170. View abstract.
- Lemli, J. Metabolism of sennosides--an overview. Pharmacology 1988;36 Suppl 1:126-128. View abstract.
- Heldwein, W., Sommerlatte, T., Hasford, J., Lehnert, P., Littig, G., and Muller-Lissner, S. Evaluation of the usefulness of dimethicone and/or senna extract in improving the visualization of abdominal organs. J Clin.Ultrasound 1987;15:455-458. View abstract.
- Kinnunen, O. and Salokannel, J. The carry-over effect on the bowel habit in elderly long-term patients of long-term bulk-forming products containing stimulant laxative. Acta Med Scand. 1987;222:477-479. View abstract.
- Bossi, S., Arsenio, L., Bodria, P., Magnati, G., Trovato, R., and Strata, A. [Clinical study of a new preparation from plantago seeds and senna pods]. Acta Biomed.Ateneo.Parmense. 1986;57(5-6):179-186. View abstract.
- Mishalany, H. Seven years' experience with idiopathic unremitting chronic constipation. J Pediatr.Surg. 1989;24:360-362. View abstract.
- Labenz, J., Hopmann, G., Leverkus, F., and Borsch, G. [Bowel cleansing prior to colonoscopy. A prospective, randomized, blind comparative study]. Med Klin.(Munich) 10-15-1990;85:581-585. View abstract.
- Lazarus, H., Fitzmartin, R. D., and Goldenheim, P. D. A multi-investigator clinical evaluation of oral controlled-release morphine (MS Contin tablets) administered to cancer patients. Hosp.J 1990;6:1-15. View abstract.
- Ziegenhagen, D. J., Zehnter, E., Tacke, W., and Kruis, W. Addition of senna improves colonoscopy preparation with lavage: a prospective randomized trial. Gastrointest.Endosc. 1991;37:547-549. View abstract.
- Soyuncu, S., Cete, Y., and Nokay, A. E. Portal vein thrombosis related to Cassia angustifolia. Clin.Toxicol.(Phila) 2008;46:774-777. View abstract.
- Wildgrube, H. J. and Lauer, H. [Combination intestinal lavage: a conservative procedure for colonoscopy]. Bildgebung 1991;58:63-66. View abstract.
- McLaughlin, A. F. Anorexia nervosa and senna misuse: nephrocalcinosis, digital clubbing and hypertrophic osteoarthropathy. Med J Aust. 9-15-2008;189:348. View abstract.
- Lim, A. K., Hooke, D. H., and Kerr, P. G. Anorexia nervosa and senna misuse: nephrocalcinosis, digital clubbing and hypertrophic osteoarthropathy. Med J Aust. 1-21-2008;188:121-122. View abstract.
- Bailey, S. R., Tyrrell, P. N., and Hale, M. A trial to assess the effectiveness of bowel preparation prior to intravenous urography. Clin.Radiol. 1991;44:335-337. View abstract.
- De, Salvo L., Borgonovo, G., Ansaldo, G. L., Varaldo, E., Floris, F., Assalino, M., and Gianiorio, F. The bowel cleansing for colonoscopy. A randomized trial comparing three methods. Ann.Ital.Chir 2006;77:143-146. View abstract.
- Miles, C. L., Fellowes, D., Goodman, M. L., and Wilkinson, S. Laxatives for the management of constipation in palliative care patients. Cochrane.Database.Syst.Rev. 2006;:CD003448. View abstract.
- Kositchaiwat, S., Suwanthanmma, W., Suvikapakornkul, R., Tiewthanom, V., Rerkpatanakit, P., and Tinkornrusmee, C. Comparative study of two bowel preparation regimens for colonoscopy: senna tablets vs sodium phosphate solution. World J Gastroenterol. 9-14-2006;12:5536-5539. View abstract.
- Patanwala, A. E., Abarca, J., Huckleberry, Y., and Erstad, B. L. Pharmacologic management of constipation in the critically ill patient. Pharmacotherapy 2006;26:896-902. View abstract.
- Beuers, U., Spengler, U., and Pape, G. R. Hepatitis after chronic abuse of senna. Lancet 2-9-1991;337:372-373. View abstract.
- Guo, H., Huang, Y., Xi, Z., Song, Y., Guo, Y., and Na, Y. Is bowel preparation before excretory urography necessary? A prospective, randomized, controlled trial. J Urol. 2006;175:665-668. View abstract.
- Radaelli, F., Meucci, G., Imperiali, G., Spinzi, G., Strocchi, E., Terruzzi, V., and Minoli, G. High-dose senna compared with conventional PEG-ES lavage as bowel preparation for elective colonoscopy: a prospective, randomized, investigator-blinded trial. Am J Gastroenterol. 2005;100:2674-2680. View abstract.
- Burlefinger, R. J. and Schmitt, W. [Letter to the Journal of Gastroenterology. Comment on the article "Senna or bisacodyl before lavage preparation for colonoscopy: prospective randomized comparative study", by D. J. Ziegenhagen, E. Zehnter, W. Tacke, T. H. Gheorghiu, W. Kruis]. Z.Gastroenterol. 1992;30:376. View abstract.
- Sonmez, A., Yilmaz, M. I., Mas, R., Ozcan, A., Celasun, B., Dogru, T., Taslipinar, A., and Kocar, I. H. Subacute cholestatic hepatitis likely related to the use of senna for chronic constipation. Acta Gastroenterol.Belg. 2005;68:385-387. View abstract.
- Ramkumar, D. and Rao, S. S. Efficacy and safety of traditional medical therapies for chronic constipation: systematic review. Am J Gastroenterol. 2005;100:936-971. View abstract.
- Ziegenhagen, D. J., Zehnter, E., Tacke, W., Gheorghiu, T., and Kruis, W. Senna vs. bisacodyl in addition to Golytely lavage for colonoscopy preparation--a prospective randomized trial. Z.Gastroenterol. 1992;30:17-19. View abstract.
- BALDWIN, W. F. CLINICAL STUDY OF SENNA ADMINISTRATION TO NURSING MOTHERS: ASSESSMENT OF EFFECTS ON INFANT BOWEL HABITS. Can.Med Assoc.J 9-14-1963;89:566-568. View abstract.
- Chilton, A. P., O'Sullivan, M., Cox, M. A., Loft, D. E., and Nwokolo, C. U. A blinded, randomized comparison of a novel, low-dose, triple regimen with fleet phospho-soda: a study of colon cleanliness, speed and success of colonoscopy. Endoscopy 2000;32:37-41. View abstract.
- Valverde, A., Hay, J. M., Fingerhut, A., Boudet, M. J., Petroni, R., Pouliquen, X., Msika, S., and Flamant, Y. Senna vs polyethylene glycol for mechanical preparation the evening before elective colonic or rectal resection: a multicenter controlled trial. French Association for Surgical Research. Arch.Surg. 1999;134:514-519. View abstract.
- Stickel, F. and Schuppan, D. Herbal medicine in the treatment of liver diseases. Dig.Liver Dis. 2007;39:293-304. View abstract.
- Hangartner, P. J., Munch, R., Meier, J., Ammann, R., and Buhler, H. Comparison of three colon cleansing methods: evaluation of a randomized clinical trial with 300 ambulatory patients. Endoscopy 1989;21:272-275. View abstract.
- Borkje, B., Pedersen, R., Lund, G. M., Enehaug, J. S., and Berstad, A. Effectiveness and acceptability of three bowel cleansing regimens. Scand J Gastroenterol 1991;26:162-166. View abstract.
- Krumbiegel G and Schulz HU. Rhein and aloe-emodin kinetics from senna laxatives in man. Pharmacology 1993;47(suppl 1):120-124. View abstract.
- de Witte, P. and Lemli, L. The metabolism of anthranoid laxatives. Hepatogastroenterology 1990;37:601-605. View abstract.
- Duncan AS. Standardized senna as a laxative in the puerperium; a clinical assessment. Br Med J 1957;1:439-41. View abstract.
- Faber P, Strenge-Hesse A. Relevance of rhein excretion into breast milk. Pharmacology 1988;36 Suppl 1:212-20. View abstract.
- Faber P, Strenge-Hesse A. Senna-containing laxatives: excretion in the breast milk? Geburtshilfe Frauenheilkd 1989;49:958-62. View abstract.
- Hagemann TM. Gastrointestinal medications and breastfeeding. J Hum Lact 1998;14:259-62. View abstract.
- Werthmann WM Jr, Krees SV. Quantitative excretion of Senokot in human breast milk. Med Ann Dist Columbia 1973;42:4-5. View abstract.
- Prather CM. Pregnancy-related constipation. Curr Gastroenterol Rep 2004;6:402-4. View abstract.
- Kittisupamongkol W, Nilaratanakul V, Kulwichit W. Near-fatal bleeding, senna, and the opposite of lettuce. Lancet 2008;371:784. View abstract.
- Senokot Package Labeling. Purdue Products L.P. 2007.
- MacLennan WJ, Pooler AFWM. A comparison of sodium picosulphate ("Laxoberal") with standardised senna ("Senokot") in geriatric patients. Curr Med Res Opin. 1974;2:641-7. View abstract.
- Passmore AP, Wilson-Davies K, Stoker C, Scott ME. Chronic constipation in long stay elderly patients: a comparison of lactulose and a senna-fibre combination. BMJ 1993;307:769-71. View abstract.
- Passmore AP, Davies KW, Flanagan PG, et al. A comparison of Agiolax and lactulose in elderly patients with chronic constipation. Pharmacology 1993;47:249-52. View abstract.
- Kinnunen O, Winblad I, Koistinen P, Salokannel J. Safety and efficacy of a bulk laxative containing senna versus lactulose in the treatment of chronic constipation in geriatric patients. Pharmacology 1993;47:253-5. View abstract.
- [No authors listed] Senna in the puerperium. Pharmacology 1992;44:23-5. View abstract.
- Shelton MG. Standardized senna in the management of constipation in the puerperium: A clinical trial. S Afr Med J 1980;57:78-80. View abstract.
- Perkin JM. Constipation in childhood: a controlled comparison between lactulose and standardized senna. Curr Med Res Opin 1977;4:540-3. View abstract.
- Sondheimer JM, Gervaise EP. Lubricant versus laxative in the treatment of chronic functional constipation of children: a comparative study. J Pediatr Gastroenterol Nutr 1982;1:223-6. View abstract.
- Ramesh PR, Kumar KS, Rajagopal MR, et al. Managing morphine-induced constipation: a controlled comparison of an Ayurvedic formulation and senna. J Pain Symptom Manage 1998;16:240-4. View abstract.
- Ewe K, Ueberschaer B, Press AG. Influence of senna, fibre, and fibre + senna on colonic transit in loperamide-induced constipation. Pharmacology 1993;47:242-8. View abstract.
- Arezzo A. Prospective randomized trial comparing bowel cleaning preparations for colonoscopy. Surg Laparosc Endosc Percutan Tech. 2000;10:215-7. View abstract.
- van Os FH. Anthraquinone derivatives in vegetable laxatives. Pharmacology 1976;14:7-17. View abstract.
- Godding EW. Laxatives and the special role of senna. Pharmacology 1988;36:230-6. View abstract.
- Joo JS, Ehrenpreis ED, Gonzalez L, et al. Alterations in colonic anatomy induced by chronic stimulant laxatives: the cathartic colon revisited. J Clin Gastroenterol 1998;26:283-6. View abstract.
- Langmead L, Rampton DS. Review article: herbal treatment in gastrointestinal and liver disease--benefits and dangers. Aliment Pharmacol Ther 2001;15:1239-52. View abstract.
- Prior J, White I. Tetany and clubbing in patient who ingested large quantities of senna. Lancet 1978;2:947. View abstract.
- Xing JH, Soffer EE. Adverse effects of laxatives. Dis Colon Rectum 2001;44:1201-9. View abstract.
- Vanderperren B, Rizzo M, Angenot L, et al. Acute liver failure with renal impairment related to the abuse of senna anthraquinone glycosides. Ann Pharmacother 2005;39:1353-7. View abstract.
- Seybold U, Landauer N, Hillebrand S, Goebel FD. Senna-induced hepatitis in a poor metabolizer. Ann Intern Med 2004;141:650-1. View abstract.
- Marlett JA, Li BU, Patrow CJ, Bass P. Comparative laxation of psyllium with and without senna in an ambulatory constipated population. Am J Gastroenterol 1987;82:333-7. View abstract.
- Nusko G, Schneider B, Schneider I, et al. Anthranoid laxative use is not a risk factor for colorectal neoplasia: results of a prospective case control study. Gut 2000;46:651-5. View abstract.
- American Academy of Pediatrics. The transfer of drugs and other chemicals into human milk. Pediatrics 2001;108:776-89. View abstract.
- Young DS. Effects of Drugs on Clinical Laboratory Tests 4th ed. Washington: AACC Press, 1995.
- Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
- McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
- The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
- Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
- Monographs on the medicinal uses of plant drugs. Exeter, UK: European Scientific Co-op Phytother, 1997.