Why take senokot at night?

What is senna?

Senna a stimulant laxative, it is a natural medicine derived from the senna plant.

Senna is a generic medicine, available as tablets and syrup. Senna is also available under the brand name Senokot. It is available to buy from pharmacies.

What is senna used for?

To treat constipation.

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How does senna work?

Senna works by stimulating the nerve endings in the walls of the large bowel (colon) and rectum. This makes the muscles in the bowel wall contract more often and with increased force, which moves the stools through the colon to the rectum so that the bowel can be emptied.

Senna contains sennosides that are activated by the natural bacteria found in the colon, so it doesn’t start working until it reaches this part of the gut.

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Key info to know about taking senna

▪️ Senna tablets and syrup start to work 8 to 12 hours after you take them. If you don’t have a bowel movement after three days of taking senna at bedtime you should consult your doctor.

▪️ If you find you need to use a laxative every day you should consult your doctor so that the cause of your constipation can be investigated. Laxatives should not be used on a continuous basis for longer than seven days without consulting your doctor.

▪️ Senna should not be used by people who have have symptoms such as severe abdominal pain, feeling sick and vomiting, or rectal bleeding where you don’t know the cause, as this could indicate that you have a more serious condition that needs investigating.

▪️ Constipation in children should only be treated with senna laxatives under the supervision of a doctor.

▪️ People who have had recent surgery on their bowel or have a blockage in the gut should not use senna.

▪️ People who also have symptoms such as severe abdominal pain, feeling sick and vomiting, or rectal bleeding where you don’t know the cause, as this could indicate that you have a more serious condition that needs investigating.

▪️ Senna is not known to be harmful if taken during pregnancy or if breastfeeding. However, as with all medicines, you should get advice from your doctor before taking this medicine if you’re pregnant. Other treatments of relieving constipation may be more suitable for you.

▪️ Prolonged, excessive use of laxatives like senna can lead to chronic diarrhoea, low potassium levels in the blood (hypokalaemia) and an imbalance in the amount of fluid and salts (electrolytes) in your body, particularly if you’re also taking diuretic or steroid medicines. This can cause kidney problems.

▪️ Prolonged, excessive use of laxatives such as senna may also make the constipation worse in the long-term, as the gut can become reliant on the laxative. Don’t exceed the recommended dose of senna or take it for more than a week unless advised to by your doctor.

▪️ Make sure you drink plenty of fluids while you’re taking senna, as this will also help relieve the constipation.

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Senna dosage instructions

▪️ The recommended dose should be taken at bedtime to produce relief from constipation the following morning.

▪️ The usual recommended dose for adults and children over 12 years old is one or two tablets to be taken at night.

▪️ You can take senna tablets and liquid either with or without food.

▪️ If you don’t have a bowel movement after three days of taking senna at bedtime you should consult your doctor.

Possible side effects of senna

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with senna. Just because a side effect is stated here doesn’t mean that all people using senna will experience that or any side effect.

Senna increases the activity of the muscle in the gut it can cause abdominal cramps, spasms of diarrhoea.

Senna may cause discolouration of the urine – red-orange or dark yellow colour urine. This is harmless and nothing to worry about.

You should read the patient information leaflet that is supplied with your medication for more information about side effects associated with senna. You can find a copy of this here

If you think you have experienced side effects from senna, you can report them using the yellow card scheme.

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Taking senna with other medicines

Senna shouldn’t affect other medicines if it’s taken as directed. However, if you’re buying it without a prescription and you’re already taking any other medicines it’s always best to get advice from your pharmacist first, to make sure senna is appropriate to take alongside your other medicines.

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Last updated 03.12.32019

Rita Ghelani (BPharm, MRPharmS) Pharmacist A UK registered practising pharmacist with over 20 years’ experience, Rita is a member of the medical journalists’ association (MJA) and has a wealth of experience in community pharmacy.

How does this medication work? What will it do for me?

Senna belongs to the class of medications called stimulant laxatives. It is used to relieve occasional constipation that is not caused by other medications or medical conditions. This medication works by increasing the muscle activity in the digestive system, causing waste material to be eliminated as stool. It usually produces a stool between 6 and 12 hours after taking the medication.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

Each mL of syrup contains standardized sennosides 1.7 mg. Nonmedicinal ingredients: alcohol (7%), chocolate flavour, cocoa flavour, methylparaben, propylparaben, sodium hydroxide, sucrose (66 g/100 mL), and water.

Each round, brown tablet contains standardized sennosides 8.6 mg. Nonmedicinal ingredients: cornstarch, magnesium stearate, and microcrystalline cellulose.

How should I use this medication?

The usual adult dose of senna is 10 mL to 15 mL of syrup or 2 to 4 tablets, 1 or 2 times a day. The maximum dose is 15 mL or 4 tablets twice a day.

If you are pregnant, your doctor may recommend this medication, however the recommended dose is lower during pregnancy. During pregnancy, the recommended dose is 5 mL to 10 mL of the syrup or 1 to 2 tablets taken 1 or 2 times a day. The maximum dose is 10 mL or 2 tablets twice a day.

Children’s doses are generally smaller than those taken by adults. For children from 6 to 12 years of age, the recommended dose is 5 mL to 10 mL of syrup or 1 to 2 tablets taken 1 or 2 times a day. The maximum dose is 10 mL or 2 tablets twice a day.

For children between the ages of 2 and 5 years, 3 mL to 5 mL of syrup may be given 1 or 2 times a day. The maximum dose for this age group is 5 mL twice a day.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor.

Use an oral syringe to measure each dose of the liquid, as it gives a more accurate measurement than household teaspoons.

This medication should be taken at bedtime, with a stool being produced sometime after waking. If there is no bowel movement after using senna, or there is rectal bleeding, contact your doctor as soon as possible.

If you are taking this medication regularly and miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not use this medication if you:

  • are allergic to senna or any ingredients of this medication
  • have appendicitis
  • have blockage in the digestive tract
  • have Crohn’s disease, ulcerative colitis, or inflammatory colon disease
  • have severe dehydration
  • have undiagnosed abdominal pain, fever, nausea, or vomiting
  • have weakened muscle activity of the digestive system

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • abdominal cramps
  • discolouration of body fluids (e.g., breast milk, urine, stools)
  • nausea
  • vomiting

Although most of the side effects listed below don’t happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • ongoing diarrhea

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Fluid and electrolyte balance: If senna is taken for too long a period of time, it may cause diarrhea and affect the levels of fluid and electrolytes in the blood. If you experience symptoms of fluid and electrolyte imbalance such as thirst, muscle pains, or cramps; dry mouth; numb hands, feet, or lips; or racing heartbeat, contact your doctor as soon as possible. Inform your doctor of any medications for heart or blood pressure that you may be taking, as these also increase the risk of fluid and electrolyte changes.

General: If you experience a sudden change in your bowel movements that lasts for 2 weeks or more, do not take this medication without first talking to your doctor. If you take senna and it does not seem to help with your constipation or if rectal bleeding occurs, stop using this medication and contact your doctor.

Other medications: Although senna does not directly affect the actions of other medications, taking it too close to other medications may change how much of the other medication is absorbed by the body. Avoid taking senna within 2 hours of any other medications.

Overuse of medication: As with any stimulant laxative, ongoing use of senna may cause the bowel to become dependent on the medication to produce stools. Unless you doctor has recommended a specific schedule, do not take senna for more than 1 week.

Pregnancy: This medication is considered safe to use during pregnancy, however is should only be used when recommended by a doctor. Lower than usual adult doses should be used.

Breast-feeding: This medication is considered safe to use while breast-feeding, however it should only be used when recommended by a doctor.

Children: The safety and effectiveness of using this medication have not been established for children less than 2 years of age.

What other drugs could interact with this medication?

Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. In many cases, interactions are intended or are managed by close monitoring. Speak to your doctor about how any drug interactions are being managed or should be managed.

All material copyright MediResource Inc. 1996 – 2020. Terms and conditions of use. The contents herein are for informational purposes only. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Source: www.medbroadcast.com/drug/getdrug/Senokot

About senna

Type of medicine A stimulant laxative
Used for Constipation
Also called Senokot®; Potter’s Senna®
Available as Tablets and oral liquid medicine

Constipation is a common problem. It can mean either going to the toilet less often than usual to empty your bowels, or passing hard or painful stools. Constipation can be caused by a number of things. Not eating enough fibre or not drinking enough fluid can cause constipation. Some conditions (such as pregnancy) can cause constipation, as can a lack of exercise or movement (such as being ill in bed) and some medicines.

Often, increasing the amount of fibre in your diet (such as by eating more fruit, vegetables, cereals, and wholemeal bread) and drinking plenty of water each day can effectively prevent or relieve constipation.

You could be recommended senna as a laxative to help relieve constipation if you cannot increase the fibre in your diet, or if this is insufficient. Senna works by encouraging the muscles in your bowel to move stools through your body. This helps you to go to the toilet. It usually has an effect within 8-12 hours. It is available to buy without a prescription at pharmacies and other retail outlets.

Before taking senna

To make sure that this is the right treatment for you, before you start taking senna it is important that you speak with your doctor or a pharmacist if:

  • You are pregnant or breastfeeding. This is because, if you are expecting a baby or breastfeeding, medicines should only be taken on the advice of a doctor or nurse.
  • It is intended for a child. Laxatives should only be given to children on the advice of a doctor, or a healthcare professional experienced in the management of constipation in children.
  • You are so constipated that you think you may have a blockage.
  • You are taking or using any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines.
  • You have ever had an allergic reaction to a medicine.

How to take senna

  • Before taking senna, read the manufacturer’s printed information leaflet from the pack. It will give you more information about the medicine and will provide you with a full list of the side-effects which you could experience.
  • The usual adult dose is two to four tablets, or two to four 5 ml spoonfuls (10-20 ml) of liquid medicine once a day. Take senna in the evening. It should only be used for a few days – this is because your bowel can start to rely on this type of laxative to make it work rather than working on its own. If you are still constipated after taking senna for three days, you should make an appointment to speak with your doctor.
  • If a doctor or healthcare professional has recommended senna for your child, check the label on the pack carefully to make sure that you give the correct dose for the age of your child.

Getting the most from your treatment

  • It is important for you to drink plenty while you are constipated. Adults should aim to drink at least two litres (about 8-10 cups) of fluid per day. Most sorts of drink will do but, as a start, try just drinking a glass of water 3-4 times a day in addition to what you normally drink.
  • Try to eat a balanced diet containing high-fibre foods such as wholemeal and wholegrain breads and cereals, fruit and vegetables, brown rice and wholemeal pasta. If you are not used to a high-fibre diet, it may be best to increase the amount of fibre you eat gradually.
  • Keeping your body active will help you to keep your digestive system moving, so try to take some regular daily exercise.
  • You may wish to include some foods in your diet that contain sorbitol. Sorbitol is a naturally occurring sugar. It is not digested very well and draws water into your bowel which has an effect of softening stools. Fruits (and their juices) which have a high sorbitol content include apples, apricots, gooseberries, grapes (and raisins), peaches, pears, plums, prunes, raspberries and strawberries.
  • Food such as pastries, puddings, sweets, cheese and cake can make constipation worse and are probably best avoided.
  • You can read more about how to prevent or treat constipation in the separate condition leaflets called Constipation in Adults and Constipation in Children.

Can senna cause problems?

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the ones which can occur with senna. You will find a full list in the manufacturer’s information leaflet supplied with your medicine. Speak with your doctor or pharmacist if any of the following continue or become troublesome.

Side-effects of senna What can I do if I experience this?
Stomach pain or cramp, diarrhoea Stop taking senna

If you experience any other symptoms which you think may be due to senna, please speak with your doctor or pharmacist for further advice.

How to store senna

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light.

Important information about all medicines

If you buy any medicines check with a pharmacist that they are safe to take with your other medicines.

Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.

If you are having an operation or dental treatment, tell the person carrying out the treatment which medicines you are taking.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy who will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.


Active ingredient (in each tablet)
Docusate sodium 50 mg………………………………….
Sennosides 8.6 mg…………………………………….. Purpose
Stool softener


  • Relieves occasional constipation (irregularity)
  • Generally causes bowel movement in 6-12 hours


Do not use

  • If you are now taking mineral oil, unless directed by a doctor
  • Laxative products for longer than 1 week unless directed by a doctor

Ask a doctor before use if you have

  • Stomach pain
  • Nausea
  • Vomiting
  • Noticed a sudden change in bowel habits that continues over a period of 2 weeks

Stop use and ask a doctor if you have rectal bleeding or fail to have a bowel movement after use of a laxative. These may indicate a serious condition.

If pregnant or breast-feeding, ask a health professional before use.
Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center right away.

Other information

  • Each tablet contains: calcium 10 mg, sodium 4 mg. VERY LOW SODIUM
  • Store at 25°C (77°F); excursions permitted between 15°-30°C (59°-86°F)

Inactive ingredients
Dicalcium phosphate, D&C Yellow #10 Aluminum Lake, FD&C Yellow #6 Aluminum Lake, lecithin, magnesium stearate, microcrystalline cellulose, polyethylene glycol, polyvinyl alcohol, pregelatinized starch, sodium benzoate, talc, and titanium dioxide

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