Bowel preparation instructions for the use of Senna tablets and Picolax prior to your procedure
Picolax and Senna are laxatives used to clean out your bowel prior to a colonoscopy or flexible sigmoidoscopy. It is important that you follow these instructions and dietary advice below as this will help the endoscopist get clear views of the lining of your bowel. If your bowel is not properly prepared your procedure may be unsuccessful or cancelled.
One packet of Senna tablets and one pack of Picolax (containing two sachets) are enclosed. This comes with manufacturer’s instructions inside the packaging. Do not follow the manufacturer’s instructions! Please follow our local instructions below. Our instructions have been designed by our consultants to provide the best results so that we can carry out your procedure successfully.
However, it is important you still read the manufacturer’s leaflet before you take the bowel preparation. The leaflet will tell you about allergies, possible side effects, and the effects it can have on oral medications.
If you have any questions about the bowel preparation, including taking your regular medications, please contact the individual Endoscopy Units:
- Royal Lancaster Infirmary telephone: 01524 583724
- Westmorland General Hospital telephone: 01539 715175
- Furness General Hospital telephone: 01229 402960
If you take anticoagulant, antiplatelet, or weight loss medications, please contact the Endoscopy unit at least seven days prior to your appointment.
If you have diabetes, please contact the specialist diabetic team or your GP practice for advice.
Seven days before your procedure:
- If taking iron tablets, please stop until after your procedure.
Five days before your procedure:
- If taking any constipation medicines, for example: Loperamide and Codeine Phosphate, stop taking these until after the procedure.
- Continue taking all other medication as prescribed and any laxatives until after your procedure.
- Commence a low fibre diet and continue this until you start taking your bowel prep medication. It is very important that you follow a low fibre diet as this cleanses your bowel. Eating high fibre foods may affect how well your bowel preparation works. Please see the table below for foods we recommend.
| Low Fibre Foods Allowed | High Fibre Foods NOT Allowed |
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Four days before your procedure:
- Take 2 x 7.5mg Senna tablets at bedtime.
Three days before your procedure:
- Take 2 x 7.5mg Senna tablets at bedtime.
Two days before your procedure:
- Take 2 x 7.5mg Senna tablets at bedtime
Please return the remainder of the packet to your local community pharmacy, who will safely dispose of these for free.
DO NOT throw your remaining medication in the bin, sink or toilet. Throwing medicines away, such as in the bin with household waste, could lead to them being found by children, pets, or those they are not intended for. Flushing medication or pouring them down the sink poses risks to the environment.
The day before your procedure:
- Have a good breakfast and light lunch of foods taken from the permitted list on page four until 12 noon.
- From 12 noon onwards, do not eat any solid food until after your examination but drink plenty of clear liquids. Please see the table below of suitable clear fluids.
Drinks allowed |
Drinks to avoid |
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If you are having a morning procedure
(up to 12 noon) please follow the instructions below:
If you take oral medications regularly in the evening, please take these medications one hour before starting the first sachet of Picolax.
At 4pm dissolve the contents of one packet of Picolax in a cup of water (approximately 150ml). Please be aware that the mixture may fizz over when the powder is added, so consider mixing in a larger jug or container. If it becomes warm, wait until it cools long enough before pouring into a suitable glass and drink.
Drink at least 5 x 250ml of clear fluids over 4 hours until your next Picolax dose.
At 8pm dissolve the second packet of Picolax in a cup of water (approximately 150ml). Please be aware that the mixture may fizz over when the powder is added, so consider mixing in a larger jug or container. If it becomes warm, wait until it cools long enough before pouring into a suitable glass and drink.
During the rest of the evening, drink at least 750ml of clear fluid, spread over several hours.
You may continue to take sips of clear fluids up until two hours before the procedure.
Please see the table above for examples of clear fluids we advise you to drink.
If you are having an afternoon procedure
(1pm onwards) please follow the instructions below:
If you take oral medications regularly in the evening, please take these medications one hour before starting the first sachet of Picolax.
At 6pm dissolve the contents of one packet of Picolax in a cup of water (approximately 150ml). Please be aware that the mixture may fizz over when the powder is added, so consider mixing in a larger jug or container. If it becomes warm, wait until it cools long enough before pouring into a suitable glass and drink.
During the rest of the evening, drink at least 5 x 250ml of clear fluids.
On the day of your procedure at 6am dissolve the contents of one packet of Picolax in a cup of water (approximately 150ml). Please be aware that the mixture may fizz over when the powder is added, so consider mixing in a larger jug or container. If it becomes warm, wait until it cools long enough, before pouring into a suitable glass and drink.
Drink at least 750ml of clear fluids, spread over several hours...
If you take oral medications regularly in the morning, please take these medications two hours after taking Picolax.
You may continue to take sips of clear fluids up until two hours before the procedure.
Please see the table above for examples of clear fluids we advise you to drink.
Side effects
Please expect to have frequent bowel movements which will eventually turn to diarrhoea. We would strongly advise that you stay within easy reach of a toilet once you start taking the preparation medicine. If you need to, please use a barrier cream such as Zinc and Castor Oil, or Sudocrem on your bottom to prevent soreness.
Some stomach cramping is normal.
Drink plenty of clear fluids to avoid becoming dehydrated, feeling dizzy, faint, or getting a headache.
If you vomit up the preparation medicine at any time, or you have any other concerns regarding side effects please contact us directly during our hours of opening:
Royal Lancaster Infirmary
(8am-6pm) telephone: 01524 583724
Westmorland General Hospital
(8am-6pm) telephone: 01539 715175
Furness General Hospital
(8am-6pm) telephone: 01229 402960
If outside these hours, please call 111.
UHMBT is a university hospital trust and a learning environment, therefore learners (post-graduate doctors/dentists, medical/dental students, student nurses, student midwives or other student allied health professionals) may be present, under appropriate supervision, for your care and treatment.
Please let your healthcare professional know if you do not wish to have learners present.
Date of publication: 04/03/2026
Reference code: PIL194IND061
Review date: 01/03/2029