Senna: An FDA-Approved, Non-Prescription Laxative

Senna Leaves

Senna is an herb – also known as Senna alexandrina, that is a popular laxative available OTC without any sort of prescription required. 

Herbal extracts of the leaves and flowers of senna have been traditionally used as a laxative and stimulant. Senna derives its benefits from “glucosides” – called senna glycosides or sennosides. 

How Does Senna Work?

These sennosides are not absorbed in the intestine but rather utilized by bacteria to release active compounds (rhein, rhein-anthrone, moieties). These compounds function as irritants within the colon, which promotes evacuation and thus, the ‘laxative’ effect people have come to know senna for. 

Usually, senna is very poorly absorbed itself – rather, it increases the water/moisture content of stool by preventing water and electrolyte absorption and increasing secretion via the colon. 

What are Sennosides and Glucosides? 

A “glucoside” is a glycoside derived from glucose within plants, herbal extracts, and foods. Different glycosides from different plants can have certain immune-modulating effects on the body, or display antioxidant properties. 

Sennosides are just a type of glucoside. Sennosides are sometimes given by themselves as a medication to help treat constipation. They can also be used in medical settings to clear the intestinal system prior to a bowel exam or surgery. 

Other metabolites present in senna, like “rhein,” can also exert protective and beneficial effects – anti-inflammatory, anti-cancer, hepatoprotective, and antimicrobial. Rhein “suppresses the production of pro-inflammatory cytokines like interleukin-1 and interleukin-6.” 

Is Senna Safe – How Long Can I Take It?

Often, senna will be included as an active ingredient in over-the-counter (OTC) laxative medication – with the typical dose being 15 mg-30 mg sennosides two times daily. Senna, like other laxatives, is only a short-term recommendation. They should not be used for prolonged periods of time as they can cause a severe electrolyte imbalance. Long-term use can lead to diarrhea, weight loss, and abdominal pain. 

When senna is used at the recommended dosage for a limited period of time, there are few reported side effects. Most of these side effects are completely mild and are related to the product as a laxative herb — diarrhea, namely.

In very rare cases of prolonged overuse, liver injury was reported. In these individuals, it was always mild and resolved immediately with discontinuation of the senna. This was after 4-5 months of prolonged, daily use. 

Senna has been known to interact with certain medications, such as birth control pills. Senna can actually decrease how much estradiol is absorbed from each pill. Senna may also interact with blood thinners like warfarin or diuretic drugs. 

When taking senna, you always want to ensure you have adequate electrolyte balance and are consuming enough potassium. Senna should never be used if you are dehydrated or already having diarrhea/loose stool. 

We always recommend consulting with a health care practitioner prior to use when it comes to senna or any other herbal laxative. 

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