What is senna used for?

• Treating constipation. Senna tablets and liquids can be bought without a prescription from pharmacies or may be prescribed by your doctor.

How does senna work?

• Senna is a type of medicine called a stimulant laxative. It 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. Senna tablets and syrup start to work 8 to 12 hours after you take them.

How do I take senna?

• Follow the instructions given by your doctor, or in the packet leaflet that comes with medicine, regarding the senna dose to take. The recommended dose should be taken at bedtime to produce relief from constipation the following morning.
• 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.
• 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.
• Make sure you drink plenty of fluids while you're taking senna, as this will also help relieve the constipation.

Who should get medical advice before taking senna?

• People who have recently had surgery on their bowel.
• Children. Constipation in children should only be treated with laxatives under the supervision of a doctor.
• 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.

Who shouldn't take senna?

• People with a blockage in the gut (intestinal obstruction).
• People who are allergic to any ingredient of the medicine. Check the ingredients in the leaflet provided with the medicine if you know you have specific allergies.

Can I take senna while pregnant or breastfeeding?

• Senna is not known to be harmful if taken during pregnancy. However, as with all medicines, you should get advice from your doctor before taking this medicine if you're pregnant, particularly if you're in your first trimester. Other methods of relieving constipation may be more suitable for you.
• Senna is not known to be harmful if taken by women who are breastfeeding.

What are the 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.

• As senna increases the activity of the muscle in the gut it can cause abdominal cramps.
• 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, among others. Prolonged, excessive use 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.

Can I take senna with other medicines?

Senna shouldn't affect other medicines if it's taken as directed in the leaflet. 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.

References:

http://www.netdoctor.co.uk/medicines/digestive-health/a8132/senna-senokot/

http://www.senokot.com

https://www.drugs.com/cdi/senokot.html

http://senokot.ca/constipation-101.php

https://en.wikipedia.org/wiki/Senna_glycoside

http://patient.info/medicine/senna-for-constipation-potters-senna-senokot