Senna, also known as cassia, is a flowering plant that tends to grow in warm climates. Its primary medicinal use is as a laxative, and it's effective enough to be a main ingredient in several over-the-counter laxative products. Senna is considered to be generally safe, with the common side effects being mild. However, the long-term use or misuse of senna can cause serious side effects that are important to know about.
According to the "PDR for Herbal Medicines," when senna is used as directed, the most common complaint is gastrointestinal discomfort. This occurs due to the drug's purgative effect. These side effects include stomach cramps, bloating, gas and diarrhea. Some of these can be minimized by reducing the dose taken, but if they become serious, immediately cease taking senna and contact your doctor.
Long-term use of senna can lead to electrolyte imbalances, including low potassium. Low levels of potassium can cause a number of serious health problems, including muscle weakness, confusion, inhibition of intestinal motility and cardiac arrhythmia.
Finger clubbing is a side effect typically seen in senna misuse due to anorexia. It's caused by long-term and high-dose usage not intended to relieve constipation, but rather to promote dangerous weight loss. A study published in the April 1981 issue of The Lancet found that the finger clubbing was reversible with the cessation of senna intake and a restoration of body mass, but several letters published in the Medical Journal of Australia in response to a 2008 article titled "Anorexia Nervosa and Senna Misuse" question the reversibility of finger clubbing due to senna abuse.
The "PDR for Herbal Medicines" explains that occupational hypersensitivity is a rare side effect to senna. The resulting hypersensitivity manifests as asthma, rhinoconjunctivitis and allergy.
A study published in the June 1998 issue of the Journal of Clinical Gastroenterology found that chronic use of stimulant laxatives such as senna resulted in an anatomic alteration of the colon in which there was a loss of haustral folds, suggesting "neuronal injury or damage to colonic longitudinal musculature." Chronic use was defined as three times per week for over a year.