What is Senna: Uses, Warnings & Interactions

Updated May 14, 2025  •  Published Dec 30, 2020

Senna is a plant that has several medicinal properties, but people primarily encounter senna in laxatives. Though “senna” and “sennosides” are often used interchangeably, sennoside A and sennoside B are sugar molecules that are the two active ingredients in senna. Senna laxatives contain only sennosides. However, some senna products contain dried senna leaves. They can be used as laxatives, too. 

Sennosides are a stimulant laxative. They cause the colon to contract more often and more forcefully. In this way, stools move more quickly through the colon. Sennosides also increase the water content of the colon and the stools, so sennoside laxatives are sometimes marketed as stool softeners.

Senna overview

BRAND NAMES:

  • Black Draught, Evac-U-Gen, Ex-Lax, Fletcher’s Laxative, Geri-Kot, Perdiem, Prunelax, Senna-Lax, Senna Tabs, Senna-Time, Senokot, Smooth Move, Swiss Kriss

Generic Names:

  • Senna, sennosides, senna glycosides

Uses:

  • It treats constipation by helping you have a bowel movement.

Therapeutic Classes:

  • Gastrointestinal agent, laxative, stimulant laxative, stool softener

Forms:

  • Tablet, capsule, chewable tablet, chocolate bar, oral solution, syrup, tea, flakes, powder

How it’s taken:

  • By mouth

What is Senna used for?

Senna has many medicinal uses, but senna-derived products are typically sold as laxatives to help with constipation. Some dried senna products are marketed as having weight loss, stomach cleansing, colon cleansing, or detoxification benefits.

What form(s) does Senna come in

  • Senna laxatives usually contain only senna’s active ingredients (sennosides), so “senna” and “sennosides” are two different things. However, some senna products contain dried senna leaf or pods.

  • Laxative products always list their dosage strengths in terms of the amount of sennosides they contain. “8.6 mg” means “8.6 milligrams of sennosides.” 

  • Capsule

    • 8.6 mg

  • Tablet

    • 8.5 mg

    • 12 mg

  • Chewable tablet

    • 3 mg

    • 8.6 mg

  • Chocolate bar

    • 15 mg/piece

  • Liquid/syrup

    • 8.8 mg/5 mL (teaspoon)

  • Maximum strength liquid

    • 25 mg/15 mL (tablespoon)

  • Flakes

    • 13 mg/1/2 teaspoon

  • Teas, powders, and some herbal supplements list the amount of dried senna in the product. The amount of sennosides in each serving can vary dramatically between products or even individual servings of the same product.

What are common Senna doses?

For constipation:

  • In adults: 17.2–34.4 mg daily (capsules or tablets) OR 17.6–26.4 mg daily (liquid or syrup) OR 25–50 mg daily (maximum strength liquid) 

  • In adolescents 12–17 years of age: 8.6–34.4 mg daily (capsules or tablets) OR 17.6–26.4 mg daily (liquid or syrup) OR 25–50 mg daily (maximum strength liquid) 

  • In children 6–11 years of age: 8.6–17.2 mg daily (tablets) OR 6–12 mg daily (children’s chewable tablets) 

  • In children 2–5 years of age: 4.3–17.2 mg daily (tablets)

Common Senna prescriptions

  • Senna
    100 tablets bottle

  • Senna
    237ml of 8.8mg/5ml bottle

  • Senna
    15ml of 176mg/5ml cup

  • Senna
    5ml of 8.8mg/5ml cup

  • Senna
    8.6mg tablet

How to take Senna

  • Follow all the package instructions and recommendations when taking senna laxatives.

  • Some senna products come without instructions or recommendations. Use these products cautiously and only as needed.

  • Senna laxatives are best taken at bedtime.

  • Capsules or tablets:

    • Swallow sennoside capsules or tablets whole with a glass of water.

  • Chewable tablets:

    • The chewable tablet should be completely chewed before you swallow it.

  • Senna oral liquid or syrup:

    • Shake the liquid or syrup before measuring a dose.

    • If the dosage is given in milliliters, measure the oral liquid medicine with a medicine cup or calibrated measuring device. 

    • Use a calibrated measuring device or kitchen measuring spoon if the dose is given in teaspoons.

    • A 5 mL dose is equal to one teaspoon.

    • A 15 mL dose is equal to one tablespoon.

    • If the taste is unpleasant, the liquid or syrup can be combined with juice or milk and taken that way.

  • Powder or flakes:

    • Senna leaf flakes are put on the tongue, dry, and swallowed.

    • Senna leaf powder may be eaten plain, mixed with liquids, or sprinkled on soft food. Read the instructions. 

  • Senna tea:

    • Follow the instructions and recommendations written on the package.

  • Store senna or sennoside products at room temperature in a closed container.

What to do if you miss a dose of Senna

  • Read the dosing instructions.

  • Most senna laxatives recommend that the daily dose be taken once per day at bedtime.

    • If a dose is missed and it’s the next day, skip the missed dose. 

    • You can take the next day’s dose at any time. Taking the dose at bedtime is only a recommendation.

  • Some senna laxatives allow people to take the daily dose as one dose or split it into two doses.

    • In those cases, the morning dose can be taken at any time and combined with bedtime.

    • If it’s the next day, skip the missed dose. Take only that day’s doses.

  • Some senna laxatives require that the maximum daily dose always be split into two doses.

    • In those cases, a missed dose can be taken unless it’s almost time for the next dose. In that case, take the next dose and skip the missed dose.

  • Do not increase the daily dosage to make up for a missed dose. 

Senna contraindications

  • Senna does not have any contraindications listed in its drug information.

  • However, you should not use this medicine if you have had an allergic reaction to senna or similar products.

Senna warnings

  • Talk to a doctor if you are pregnant or breastfeeding before taking senna laxatives.

  • Before taking senna, talk to a doctor first if you have:

    • Intestinal obstruction

    • Active intestinal inflammation such as Crohn’s disease, ulcerative colitis, or appendicitis

    • Abdominal pain with no known cause

    • Stomach pain, nausea, or vomiting

    • A sudden change in bowel habits in the last two weeks

  • Do not give laxatives to children younger than 6 years old unless you talk to your doctor.

  • Stop using senna laxatives if you fail to have a bowel movement or notice rectal bleeding.

  • You should not use this laxative for longer than one week unless approved by your doctor. 

  • Tell any doctor or other healthcare provider treating you that you are using a senna laxative.

Senna interactions

  • Tell any doctor treating you that you are using a senna laxative before any new medication is prescribed.

  • Senna does not have major drug interactions.

Senna side effects

Less serious side effects

  • Nausea

  • Vomiting

  • Abdominal pain or cramping

  • Gas

  • Diarrhea

  • Discolored urine

Sources:

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