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What is Senna?
Senna is a natural laxative made from Senna fruit and the leaves of the Cassia Senna plant. Laxatives are used to treat short term, occasional constipation. Constipation is when a person has difficulty passing faeces. Senna is a stimulant laxative, which will induce a bowel movement and provide relief for your constipation.
Senna comes in various forms - as a tea, a powder, a liquid or as tablets for oral administration. The active ingredient is Sennoside. Senna is available on prescription from your doctor. Non-prescription forms are available from pharmacies and supermarkets. We can also prescribe it to you after an online consultation - contact us to find out more.
Senna is sometimes mixed with other ingredients for constipation treatment in branded products such as Senokot tablets and Manevac.
For more information on Senna tablets, refer to the patient information leaflet.
How it works
Senna is a type of stimulant laxative, and works in a different way to other laxatives such as polyethylene glycol and docusate sodium to provide relief of occasional constipation. Stimulant laxatives such as Natural Senna work by stimulating nerve endings in the rectum and colon. This forces the muscles in the colon to contract, forcing stool through the colon and through the rectum, which empties the bowel.
Senna is available as 7.5mg tablets. Senna usually takes around 8 to 12 hours to work properly.
Before you take it
You should not take Senna if you are allergic to Senna leaf or any of the other ingredients in Senna tablets. Consult the patient information leaflet, or speak with your doctor to discuss an alternative constipation treatment.
If you have paralysis or lack of muscle tone in the bowel, Senna may be unsuitable for you. Senna is also not recommended for treatment of any other conditions.
If you have already taken a laxative and are still constipated, Senna may not help you. You are advised to discuss alternative treatment with your doctor if you have not already discussed your constipation with them.
If your constipation is accompanied by other symptoms such as severe abdominal pain, nausea, vomiting or rectal bleeding, this could be an indication of a more severe abdominal problem that could need further investigation by your doctor. You should tell your doctor or pharmacist before taking Senna in this case.
Senna will be unsuitable for you if you have a gastrointestinal blockage. If you suffer from ileus, intestinal obstruction, ulcerative colitis or stenosis, make sure you speak with your doctor to discuss an alternative treatment for your constipation.
Senna should not be taken during pregnancy. It is not thought to be harmful to an unborn baby, but there are safer laxatives to take during pregnancy, such as Lactulose and Fybogel. Senna is not thought to pass into breast milk and as such is not known to be harmful while breast feeding, but you should take special precautions and seek your doctor’s advice where necessary.
If you have recently had surgery on your large intestine or colon, you must speak with your doctor to discuss whether taking Senna is suitable for you and your condition.
Senna may interact with some other medicines. If you are taking any of the following, you should check with your doctor before taking Senna.
- Water pills (diuretics) as both water pills and Senna decrease levels of potassium in the blood - by taking both together your potassium levels may be lowered too much
- Warfarin - Senna may cause diarrhoea, and diarrhoea may increase the effects of Warfarin
- Digoxin - this may decrease potassium levels in the body when taken with Senna
- If you are taking any medication for a heart condition, such as cardiac glycosides or antiarrhythmic medication
This is not a full list of warnings or potential interactions. For an exhaustive list, consult your doctor, or refer to the patient information leaflet.
You should take Senna exactly as prescribed by your doctor or pharmacist. Never exceed the stated dose. If you are in any way unsure, consult your doctor or pharmacist.
A typical dose is 7.5mg daily, taken as one tablet. You may be advised to take two tablets by your doctor. Senna is best taken at bedtime, to allow the medicine a chance to work overnight.
Swallow your tablets with plenty of water. Do not suck, crush or chew on them. Senna can be taken with or without food.
When you begin taking Senna, you should start with the lowest dose that is effective to treat your symptoms. You should stop taking Senna once bowel movement regularity has been restored.
Senna is not suitable for long term use, and you should not take Senna more than two or three times per week. If Senna does not relieve your constipation within two weeks, you should speak with your doctor.
Store Senna at room temperature, in a dry place free of moisture. Keep it out of the reach of children and pets.
Common Side Effects of Senna
Like all medications, Senna has the potential to cause mild to moderate side effects. These are not usually serious in nature and should disappear on their own as your body becomes used to the medication. These possible side effects can include:
- Stomach pain
- Stomach cramps
- Urine turning a red/brown colour
- Weight loss
- Increased rate of infection
Senna may also cause more serious, less common side effects. You should report this to your doctor and discuss an alternative method of treatment if you experience any of the following:
- Severe skin rash - usually raised, itchy and red
- Pigmentation of the gastrointestinal tract
- Low blood potassium leading to muscle weakness or cramps
It’s also possible for Senna to cause a severe allergic reaction. This is extremely rare but any allergic reaction to Senna is an emergency. You must seek medical advice straight away if you experience any of the following related side effects:
- Severe skin rash, including blistering, peeling, itching and redness
- Wheezing or difficulty breathing
- Pain in the chest or tightness in the throat
- Feeling faint
This is not an exhaustive list of side effects. For a full list, consult the patient information leaflet or speak with your doctor.
Frequently Asked Questions (FAQs)
Is Senna suitable for children?
Senna is suitable for adults and children, but laxatives must not be used by children unless they are under medical supervision. Senna is suitable for children over 12 years of age when supervised by a doctor. We do not prescribe any medication to anyone under the age of 18.
I’m pregnant. Can I take Senna?
There is no evidence to suggest Senna is harmful to an unborn baby. However, due to the way it works, it may be more suitable to take another laxative, such as Fybogel or Lactulose. Your midwife will first advise you to get more exercise, drink plenty of water and eat plenty of fibre before recommending a laxative, as often this alone can provide relief from constipation without the need for a laxative. Speak with your pharmacist or doctor if you are unsure about taking Senna while you are pregnant or breastfeeding.
What happens if I miss a dose?
If you miss a dose of Senna, take it as soon as you remember. Never take 2 doses to make up for a missed dose. If you miss your dose it may be a better idea to wait until the next day before you go to bed, to allow the medication time to work overnight.
What happens if I take too much?
An overdose of Senna can cause numerous problems, and can interfere with your long term digestive health. Repeated over-use of Senna can lead to a lazy bowel, where the muscles in the bowel become too relaxed and as a result your bowel is unable to empty itself often enough. Overdose can also lead to an electrolyte imbalance, a low level of blood potassium, dehydration or difficulty passing urine. If you believe you have overdosed on Senna, you should seek medical advice.
|Dosage Instructions||Please see medicine label for the dosage instructions.|