Senna

The Sanskrit name Svarnapatri means "golden leaf", referring to the yellowish-green to golden-brown colour of the leaves after drying. The English name "senna" comes from the Arabic word sana, reflecting the herb's historical use in Arabic and Unani medicine. The Ayurvedic Pharmacopoeia of India identifies Svarnapatri as the dried leaf of Cassia angustifolia Vahl and notes that it is cultivated mainly in southern India, particularly around Tirunelveli in Tamil Nadu. The currently accepted botanical name is Senna alexandrina Mill. Older names such as Cassia angustifolia Vahl, Cassia acutifolia Delile and Senna angustifolia (Vahl) Batka are now treated as synonyms for the same species (Royal Botanic Gardens Kew, 2021).

In Ayurvedic terms, Svarnapatri is described as having Katu (pungent), Tikta (bitter) and Kashaya (astringent) Rasa, with Laghu (light), Ruksha (dry) and Tikshna (sharp) Guna. Its Virya is Ushna (hot) and its Vipaka is Katu (pungent). The main Ayurvedic Karma of Senna is Rechana, which refers to its traditional bowel-cleansing action. Traditionally, it is considered to promote the downward movement of Apana Vata and to help clear accumulated Kapha and Pitta in the large intestine. In Ayurveda, Senna is considered heating and drying. It is traditionally combined with herbs that support digestion and used with caution in people who are weak, dehydrated or prone to dryness.

Senna is known by different names in English, Sanskrit and Indian regional languages. Older botanical names may also appear on product labels and in reference books. Some of the most common names are listed below.

• Botanical Name: Senna alexandrina Mill.
• Botanical Synonyms: Cassia angustifolia Vahl, Cassia acutifolia Delile, Cassia senna L., Senna angustifolia (Vahl) Batka
• Family: Fabaceae (Leguminosae)
• English: Senna, Indian Senna, Tinnevelly Senna, Alexandrian Senna
• Sanskrit: Svarnapatri, Markandika
• Hindi: Sanay, Sonamukhi
• Bengali: Sonamukhi
• Assamese: Sonamukhi
• Marathi: Sonamukhi
• Tamil: Nilavirai
• Telugu: Nelatangedu
• Kannada: Nelavarike
• Malayalam: Sunnamukki
• Urdu (Unani): Sana Makki

Senna's laxative effect comes mainly from a group of natural compounds found in its leaves and pods. The key constituents with recognised clinical importance are listed below.

• Sennosides A and B, the two main dianthrone glycosides and the compounds responsible for the laxative effect
• Sennosides C and D, present in smaller amounts and thought to contribute to the laxative effect in a similar way
• Rhein anthrone, the active substance formed when gut bacteria in the large intestine break down the sennosides
• Rhein, aloe-emodin and chrysophanol, related anthraquinone compounds found in the leaf
• Naphthalene glycosides, which are used as marker compounds for quality control and authentication of senna preparations
• Mucilage and resins, which make up part of the bulk of the dried leaf

Sennosides are not absorbed in the stomach or the small intestine, and they are not broken down by human digestive enzymes. They travel intact to the large intestine, where gut bacteria convert them into rhein anthrone, the compound primarily responsible for their laxative action. Roughly 90% of an oral dose is excreted in the stool (European Medicines Agency, 2018).

Senna is valued primarily for its well-established laxative action. The properties below describe how the herb is understood to act in the body.

• Stimulant laxative (Rechana karma): may increase the rhythmic muscular contractions of the large bowel.
• Antiabsorptive action: may reduce the absorption of water and sodium from the colon.
• Secretagogue action: may increase the movement of water and salts into the bowel, which helps soften the stool.
• Purgative action: at higher doses, it is traditionally described as promoting more complete bowel evacuation.
• Antimicrobial activity: has been reported in laboratory studies on leaf extracts.
• Antioxidant activity: has been reported in laboratory studies on leaf extracts.

Only the laxative properties are well established in humans (European Medicines Agency, 2018). Most evidence for the antimicrobial and antioxidant properties comes from laboratory studies on senna extracts. These findings have not been confirmed in humans and should be viewed as preliminary.

Senna acts mainly on the large intestine, and the benefits below are based on its well-established laxative action.

Relief From Occasional Constipation

Sennosides pass through the stomach unchanged and are broken down by bacteria in the colon into rhein anthrone. This active compound increases bowel muscle contractions and reduces water absorption from the colon, so stools remain softer and move through the bowel more easily, typically within 6 to 12 hours (European Medicines Agency, 2018).

Bowel Clearance Before Medical Procedures

Doctors sometimes use senna as part of bowel preparation before a colonoscopy or bowel surgery. The higher doses used for this purpose help empty the large bowel so that the lining can be examined clearly. This use is supervised by a healthcare professional and is not suitable for self-treatment.

Easing Discomfort From a Loaded Bowel

When stool remains in the colon for long periods, some people experience bloating, a feeling of abdominal heaviness and reduced appetite. By helping the bowel empty, senna may relieve these symptoms. The relief comes from clearing the bowel itself rather than from any direct effect on digestion or nutrient absorption.

Reducing Strain During a Bowel Movement

Hard stools can lead to straining, which increases pressure around the anus and may aggravate existing haemorrhoids (piles) or an anal fissure. By softening stools, senna may help reduce straining. However, fibre and bulk-forming laxatives are generally preferred for ongoing management, and senna should only be used for this purpose on the advice of a healthcare professional.

Constipation Caused by Strong Painkillers

Opioid painkillers commonly slow bowel movements and can cause constipation. Senna is commonly used under medical supervision as part of the management of opioid-induced constipation because it stimulates the bowel directly rather than adding bulk. This use should always be recommended and monitored by the treating doctor.

Disclaimer: The benefits described above relate to short term use only. Senna is not a treatment for long standing constipation and it is not a substitute for a proper medical assessment. If constipation lasts longer than a week, or comes with bleeding, vomiting, unexplained weight loss or severe abdominal pain, stop senna and see a registered medical practitioner.

Senna is commonly used for the purposes described below. These are recognised uses and do not mean that senna is suitable for everyone.

Short-Lived Constipation That Has Not Settled

Senna is generally used when constipation has lasted a few days, after dietary changes, adequate fluid intake and increased fibre have not provided sufficient relief, and provided there is no abdominal pain or rectal bleeding. It is intended for occasional episodes rather than frequent or long-term constipation.

Hospital-Directed Bowel Preparation

When a colonoscopy, sigmoidoscopy or bowel surgery is planned, the hospital may include senna in the bowel preparation regimen. The dose, timing and dietary instructions are determined by the treating team, and these instructions should be followed rather than the general directions on the product label.

Within Classical Ayurvedic Compound Formulations

Svarnapatri is one of the ingredients in classical Ayurvedic formulations such as Panchasakara Churna and Sarivadyasava. InAyurvedic practice, senna is traditionally combined with digestive herbs to help balance its heating and drying qualities.

Traditional Bedtime Tea or Churna

Many families keep dried senna leaves and use them as a bedtime infusion or take a measured amount of Churna with warm water. This is a traditional pattern of use. Regardless of the form used, senna should generally be taken as a single dose at bedtime and for short-term use only, usually for no longer than one week, unless advised by a healthcare professional.

Senna is a stimulant laxative, not a daily tonic, and it is not suitable for everyone. Read the points below before using it.

• Do not use senna if you have, or may have, bowel obstruction, bowel narrowing (stricture), paralytic ileus, appendicitis, inflammatory bowel disease such as Crohn's disease or ulcerative colitis, abdominal pain of unknown cause, or severe dehydration (European Medicines Agency, 2018)
• Avoid senna if you have unexplained rectal bleeding, persistent diarrhoea, or a sudden change in bowel habits that has not been medically assessed.
• Do not use senna for more than one week without medical advice. Longer use can lead to laxative dependence, reduced normal bowel function, and electrolyte imbalance, particularly low potassium levels (European Medicines Agency, 2018)
• Avoid senna during pregnancy or while breastfeeding unless specifically advised by your doctor.
• Do not give senna to children under 12 years of age as a self-treatment. Paediatric doses exist, but they should only be prescribed by a doctor (European Medicines Agency, 2018)
• Never use senna as a weight-loss aid. Repeated purging causes loss of fluid and electrolytes rather than body fat, and misuse of laxatives has been associated with serious health risks (National Institute of Diabetes and Digestive and Kidney Diseases, 2020)
• Maintain adequate fluid intake while taking senna, and speak to your doctor first if you take diuretics (water tablets), corticosteroids or heart medicines.
• Stop taking senna and seek medical advice immediately if you develop severe abdominal cramps, persistent vomiting, muscle weakness, dark urine, yellowing of the skin or eyes, or if you do not have a bowel movement after taking senna as directed.
• If constipation keeps returning or lasts for more than a week, consult your doctor. Repeated use of senna is not a substitute for identifying and treating the underlying cause.

Disclaimer: This is general safety information and not a substitute for advice from a registered medical practitioner or a qualified Ayurvedic physician.

Senna is available in several forms, and each should be prepared and used according to its specific instructions. Follow the directions for the product you are using.

Preparing the Leaf Powder (Churna)

• Measure the powder with a standard measuring spoon rather than a household spoon.
• Stir it into half a cup of warm water and drink it straight away before it settles.
• Take it once daily, preferably at bedtime after your evening meal.
• Do not take a second dose the same night if nothing has happened yet, as the effect usually takes 6 to 12 hours.

Making a Leaf Tea or Infusion

• Add the measured dried leaves to a cup of freshly boiled water.
• Cover the cup and leave it to infuse for about 10 minutes.
• Strain the leaves out completely and drink the liquid warm.
• Never leave the leaf steeping for longer to make it stronger, as this may increase the amount of sennosides extracted.

Taking Tablets or Capsules

• Check the sennoside strength on the label, as it varies between brands.
• Swallow the tablet or capsule whole with a full glass of water. Do not crush, break or chew it unless the label states that it is suitable for doing so.
• Take the recommended dose at bedtime and do not exceed the dose stated on the product label or advised by your healthcare professional.

Measuring a Liquid or Syrup

• Use the measuring cup, spoon or oral syringe provided with the bottle rather than a household teaspoon.
• Shake the bottle if directed on the label.
• Take the measured dose once at bedtime, then replace the cap tightly after use.

Herbs Traditionally Used With Senna

Senna products contain different amounts of sennosides, so always follow the dose on the product label for your specific preparation. The guidance below is general and should not replace advice from your doctor or healthcare professional.

Children Under 12 Years

Senna should not be given to a child under 12 as a home remedy (European Medicines Agency, 2018). Paediatric doses do exist and are used under medical supervision, but they must be prescribed and monitored by a doctor. Constipation in young children may be a sign of an underlying condition that requires medical assessment.

Teenagers Aged 12 to 17 Years

A single dose providing 15 mg to 30 mg of sennosides may be taken once at bedtime for up to one week, if appropriate and according to the product instructions. Start with the lowest effective dose. If a teenager needs senna more than occasionally, they should be assessed by a doctor rather than continue using it regularly.

Adults

A single dose of 15 mg to 30 mg of sennosides is generally taken once daily at bedtime, which is the usual dose in most standardised products. Do not exceed the maximum printed on your pack and do not take it for more than one week without medical advice (European Medicines Agency, 2018). For dried leaf powder, the Ayurvedic Pharmacopoeia of India recommends 0.5 g to 2 g daily.

Older Adults

Start with the lowest effective dose and use it for the shortest possible time. Older adults are more susceptible to dehydration and electrolyte imbalances, particularly low potassium levels, which may increase the risk of weakness, dizziness and falls. Anyone taking diuretics (water tablets), heart medicines or corticosteroids should consult their doctor before using senna.

Disclaimer: Senna should be taken only as advised by a registered medical practitioner or a qualified Ayurvedic physician. Do not increase the dose or continue treatment for longer than recommended without medical advice. Incorrect use or overdose may cause dehydration, electrolyte imbalance, including low potassium levels, and, rarely, liver injury.

Most people who use senna for a short period experience either no side effects or only mild ones. The side effects below are listed from the most to the least common.

Abdominal Cramping and Griping

Abdominal cramps are the most common side effect. Because senna works by stimulating bowel contractions, mild cramping can occur as part of its action. Using the lowest effective dose may help reduce this side effect.

Loose Stools and Diarrhoea

Diarrhoea may indicate that the dose is too high. Persistent diarrhoea can lead to fluid and electrolyte loss. Reduce the dose or stop taking senna and seek medical advice if symptoms persist.

Low Potassium and Other Salt Imbalances

Repeated or prolonged use can lead to potassium loss through the stool. Low potassium may cause muscle weakness, cramps and an irregular heartbeat, and the risk is greater in people taking diuretics (water tablets), corticosteroids or heart medicines (European Medicines Agency, 2018).

Dehydration

Excessive fluid loss from diarrhoea may cause dehydration. Older adults are particularly vulnerable. Symptoms include thirst, dark urine, feeling light-headed when standing, and passing less urine than usual.

Nausea or Vomiting

The risk may be higher with larger doses or when senna is taken on an empty stomach. Vomiting together with constipation requires medical assessment rather than further laxative use, as it may indicate an underlying bowel problem.

Harmless Change in Urine Colour

Urine may appear yellow-brown or reddish while taking senna. This colour change is caused by compounds in the herb rather than blood and usually resolves after treatment ends.

Darkening of the Bowel Lining (Melanosis Coli)

Months of regular senna use can cause dark pigmentation of the lining of the large bowel, a condition known as melanosis coli. It is usually detected during colonoscopy, is generally considered harmless, and typically fades after senna is discontinued. Its presence may indicate prolonged laxative use (National Institute of Diabetes and Digestive and Kidney Diseases, 2020).

Laxative Dependence and Reduced Bowel Function

Long-term use of senna may reduce the bowel's normal function over time and can lead to laxative dependence. For this reason, senna is recommended for short-term use only (European Medicines Agency, 2018).

Liver Injury (Rare)

Rare cases of clinically apparent liver injury have been reported, almost always after high doses or use well beyond the recommended duration. Cases of acute liver failure have also been described in people who misused senna preparations (National Institute of Diabetes and Digestive and Kidney Diseases, 2020; Vanderperren et al., 2005). Stop taking senna and seek immediate medical advice if you develop yellowing of the skin or eyes, dark urine, persistent nausea, or pain under the right side of the ribs.

Disclaimer: This list is not exhaustive. Report any unexpected reaction to your doctor or pharmacist and stop senna in the meantime.

Most interactions with senna are related to potassium loss and its effect on bowel transit time. Tell your doctor or pharmacist about all the medicines and supplements you take before starting senna.

Water Tablets (Diuretics)

Both senna and diuretics can increase potassium loss, so taking them together may raise the risk of muscle weakness, cramps and heart rhythm problems (European Medicines Agency, 2018).

Steroid Medicines (Corticosteroids)

Corticosteroids can also lower potassium levels. Combining them with senna, particularly for more than a few days, may further increase this risk (European Medicines Agency, 2018).

Digoxin and Similar Heart Medicines

Hypokalaemia can increase susceptibility to digoxin toxicity and cardiac arrhythmias (European Medicines Agency, 2018). Anyone taking digoxin should speak to their doctor before using senna.

Medicines That Affect Heart Rhythm

Medicines that prolong the QT interval may carry a greater risk of abnormal heart rhythms when potassium levels are low. Senna should therefore be used with caution alongside these medicines and only on medical advice (European Medicines Agency, 2018).

Liquorice Root (Yashtimadhu) and Products Containing It

Liquorice can lower potassium levels through a different mechanism. Taking it together with senna may increase the risk of low potassium levels (European Medicines Agency, 2018). Check the ingredients of herbal cough remedies and Ayurvedic Churnas, as they may contain liquorice.

Warfarin and Other Blood Thinners

Prolonged diarrhoea while taking senna may affect how warfarin works by altering vitamin K absorption. If you take warfarin, avoid prolonged or repeated senna use unless advised by your doctor, and seek medical advice if diarrhoea develops, as your INR may need closer monitoring.

Other Laxatives

Using senna together with another laxative may increase the risk of abdominal cramping, dehydration and electrolyte imbalance, and may increase the likelihood of laxative dependence. Use only one laxative at a time unless a healthcare professional recommends otherwise.

Oral Medicines

Senna may reduce the absorption of some medicines taken by mouth by speeding up bowel transit, particularly if diarrhoea occurs. If you take medicines where timing is important, such as levothyroxine or the combined oral contraceptive pill, ask your doctor or pharmacist how best to space your doses.

Disclaimer: This is not a complete list of interactions. Always tell your doctor and pharmacist about every prescription medicine, over the counter product and herbal preparation you take.

Storage of Senna

Sennoside content falls when senna is stored badly, which makes the dose unpredictable. Store it as follows.

• Keep dried leaves, powder, tablets or capsules in a tightly closed, airtight container.
• Store in a cool, dry place away from direct sunlight, heat and moisture. Avoid keeping it near the stove or sink.
• Keep all senna products out of the reach and sight of children.
• Do not transfer senna into an unlabelled container, as the original packaging contains important information such as the product strength, batch number and expiry date.
• Check the expiry date before use. Discard the product if it smells musty, appears damp, shows signs of mould, or has changed colour.

Buy only sealed, batch-labelled products from licensed manufacturers. Loose senna may be adulterated with related species such as Cassia fistula, Senna occidentalis, Senna sophera and Senna tora, which do not contain the same amount of sennosides (Chouksey et al., 2024)

• Senna is a stimulant laxative made from the dried leaves and pods of Senna alexandrina Mill. It is known as Svarnapatri in Ayurveda.
• It works in the large intestine, where gut bacteria convert sennosides into their active form. A bowel movement usually occurs within 6–12 hours.
• Senna is intended for the short-term relief of occasional constipation and for bowel preparation before certain medical procedures under healthcare supervision. It should not usually be used for longer than one week unless advised by a doctor.
• Senna is not a detox product or a weight-loss aid, and it should not be used to self-treat chronic digestive problems without medical advice.
• Do not use senna if you have a bowel obstruction, appendicitis, inflammatory bowel disease, unexplained abdominal pain, or severe dehydration, or during pregnancy or breastfeeding. It should not be given to children under 12 years unless prescribed by a doctor.
• Prolonged or excessive use may cause dehydration, low potassium levels, laxative dependence, and, rarely, liver injury.
• Stop taking senna and seek medical advice immediately if you develop rectal bleeding, persistent vomiting, severe abdominal pain, yellowing of the skin or eyes, dark urine, or if constipation persists or keeps returning despite treatment.