Some people may develop a dependency on senna for normal bowel movements. Therefore, senna must not be used for more than ten consecutive days. Chronic senna use can also cause loss of fluids, low potassium levels and diarrhea, all of which can lead to dehydration and potentially negative effects on the heart and muscles. The safety of senna during pregnancy and breast-feeding is controversial. Most guidelines suggest avoiding senna during the first trimester of pregnancy.^{7, 8} It is best to consult a physician. Senna is not recommended for children under the age of ten years. People with Crohn’s disease, ulcerative colitis, appendicitis, intestinal obstructions, and abdominal pain should not supplement with senna.⁹

There is one case report of a woman who developed liver failure after ingesting a large amount of senna (1 liter of a tea containing 70 grams of dried herb) daily for more than three years.¹⁰ Senna was suspected, though not proven, to be the cause of the liver failure.