Directly go to the content


Senna is a laxative that is used to treat constipation. This medicine comes in tablet form and can also be used by children older than six years of age.  



Senna is a laxative that is used to treat constipation. This medicine comes in tablet form and can also be used by children older than six years of age.  


Table of Contents 

  • What is Senna? 
  • When is Senna used? 
  • How is Senna used? 
  • What doses are available? 
  • What are the side effects of Senna? 
  • When not to use Senna? 
  • Can Senna be used in combination with other medicines? 
  • Where can I buy Senna? 
  • Can I buy Senna without a prescription? 
  • Sources 


What is Senna? 

The active ingredient senna, also known as sennoside, increases activity of the intestines to cause a bowel movement. It also helps increase the amount of water in the stool, making it softer and easier to pass. This helps relieve constipation quickly. 


When is Senna used? 

Senna is used to treat constipation. Constipation is characterised by several symptoms, including: 

  • Hard-to-pass bowel movements. 
  • Infrequent bowel movements. 
  • Stool that is hard, dry, thick or lumpy (pebble bowel movements). 
  • Stomach pain. 
  • Haemorrhoids due to straining. 

Constipation can have various causes. These triggers can cause constipation:  

  • Lack of exercise. 
  • Diet: not enough high-fibre foods (fibre stimulates bowel activity). 
  • Lack of fluids (try to drink at least 1.5 litres a day). 
  • Stress/anxiety. 
  • Change of environment and/or diet (many people suffer from ‘vacation constipation’ due to the stress of travelling, a change in routine or ‘not feeling at home’ in a new bathroom). 
  • Pregnancy. 
  • Delaying the urge to go to the toilet. 
  • Medication (constipation can also be a side effect of some prescription medications, such as certain antidepressants). 

If you suffer from constipation occasionally, for instance due to the above reasons, then you can use Senna. The active ingredient softens the stool and increases the speed at which the gut contents is pushed through the intestines. Senna normally causes a bowel movement within four to eight hours. 

Senna should not be used as a long-term treatment for chronic constipation; it is only suitable for short-term use.  


How is Senna used? 

Always use this medicine as directed by your doctor, pharmacist or chemist. Read the package leaflet provided with your medicine before use. The general guidelines for use are as follows: 

  • Senna tablets should be swallowed whole with a drink of water; do not chew or crush them. 
  • The tablet should preferably be taken at bedtime to produce a bowel movement the next day. You can also take the tablet in the morning. 
  • Take Senna exactly as directed. Do not take more of it, take it more often, or take it in a different way than directed by your doctor. Taking more than the prescribed dosage can cause abdominal cramps and diarrhoea. 
  • If you have missed a dose, then skip the missed dose and continue your regular dosing schedule. Never take a double dose to make up for the forgotten one. 
  • Continued use of Senna may make you dependent on laxatives and cause your bowels to lose their normal activity. Therefore, Senna should not be used on a continuous basis for longer than seven days. 
  • Consult a doctor if you do not have a regular bowel movement after three days of taking Senna, or if you need a laxative for long-term use.  

For more information on how to use Senna, see the package leaflet. 


What doses are available? 

Senna tablets are available in tablets of 7.5 mg. The general recommended dose is: 

  • Adults and children aged 12 years and above: two 7.5-mg tablets once a day (preferably at bedtime). 
  • Children aged 6 to 12 years: one 7.5-mg tablet once a day (preferably at bedtime). 

This medicine is not suitable for use in children under six years of age. For more information on the dosage of Senna, see the package leaflet. 


What are the side effects of Senna? 

Senna may cause side effects. The following are some of the side effects that are known to be associated with this medicine: 

  • Gastrointestinal symptoms, such as stomach ache, stomach cramps, flatulence and diarrhoea. You are particularly likely to get these side effects if you have constipation related to irritable bowel syndrome. 
  • Red or brown colouration of the urine. This is nothing to worry about.  

If you experience the above side effects, it might mean that the dose you are taking is too high. Side effects tend to be more manageable if the dose is lowered (for instance, take one tablet instead of two). 

Long-term diarrhoea can cause an imbalance of water and salt in your body, which can lead to fatigue and muscle weakness. 

For more information on the side effects of Senna, see the package leaflet. Consult a doctor if the side effects are persistent or severe. 


When not to use Senna? 

Senna is not suitable for everyone. Do not use this laxative if: 

  • You are allergic to the active ingredient senna or any other ingredient in this medicine. 
  • You have a bowel obstruction or narrowing (intestinal stricture). 
  • You have a history of paralysis or low activity of the intestinal muscles. 
  • You have appendicitis or an inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis. 
  • You have a heart and/or kidney condition. 
  • You suffer from severe dehydration. 
  • You suffer from stomach pain with unknown cause. 

Do not use this medicine if you are pregnant or breastfeeding. Consult a doctor on the use of a different laxative. 

For a complete list of warnings, see the package leaflet. Always consult a doctor if you are unsure if Senna is suitable for you. 


Can Senna be used in combination with other medicines? 

Some medicines interact with one another and influence each other’s effect. Senna is known to interact with the following medicines: 

  • Certain heart medications, such as anti-arrhythmic medicines and medicines that prolong the QT interval. 
  • Diuretics (water pills). 
  • Corticosteroids (adrenal cortex hormones). 
  • Medicines with liquorice root extract. 

For a complete list of medicines that may interfere with the way Senna works, please see the package leaflet. Your doctor will also have a list of medicines that you should avoid mixing Senna with. 


Where can I buy Senna? 

Senna is available at pharmacies, online pharmacies and drugstores.  


Can I buy Senna without a prescription? 

Senna is an over-the-counter (OTC) medicine. This means you don’t need a prescription to buy it. 


Sources (n.d.). SENNA 7.5MG TABLETS. Consulted on 25 May 2021 on 

Royal Dutch Pharmaceutical Society. (2021, 26 January). Senna. 

Dutch Digestive Diseases Foundation. (2020, 30 October). Constipation in adults.