Senokot is an over-the-counter laxative used to relieve constipation. Its active ingredient is senna, a natural compound derived from the senna plant that stimulates the muscles in your gut to push stool through. It typically produces a bowel movement within 6 to 12 hours, which is why most people take it at bedtime so it works overnight.
How Senokot Works
Senna belongs to a class called stimulant laxatives. Unlike stool softeners or fiber supplements that change the consistency of stool, Senokot works by directly triggering contractions in the intestinal wall. This speeds up the movement of waste through your colon and draws in a small amount of water, making the stool easier to pass.
Because of this mechanism, Senokot is particularly useful when constipation involves sluggish bowel motility rather than hard, dry stool alone. A joint guideline from the American College of Gastroenterology and the American Gastroenterological Association conditionally recommends senna as an evidence-based treatment for chronic constipation in adults, placing it alongside options like fiber, magnesium oxide, and osmotic laxatives.
Senokot vs. Senokot-S
Standard Senokot contains only senna. Senokot-S combines senna with a stool softener called docusate sodium. The idea is to tackle constipation from two angles: the stool softener draws water into the stool so it’s easier to pass, while the senna stimulates the intestinal muscles to move things along. If your constipation involves both hard stool and infrequent bowel movements, the combination product may be more effective than either ingredient alone.
Dosage by Age
Senokot tablets are dosed based on age, and the label recommends starting at the lowest effective dose:
- Adults and children 12 and older: 2 tablets once a day to start, up to a maximum of 4 tablets twice a day
- Children 6 to under 12: 1 tablet once a day to start, up to 2 tablets twice a day
- Children 2 to under 6: Half a tablet once a day to start, up to 1 tablet twice a day
- Children under 2: Should not take Senokot without a doctor’s guidance
Taking it at bedtime is the standard approach, since the 6 to 12 hour window means you’ll likely have a bowel movement the next morning.
Common Side Effects
The most frequent side effects are stomach cramps and diarrhea, occurring in more than 1 in 100 people. These are more likely if your constipation is related to irritable bowel syndrome. Both side effects usually reflect that the dose is slightly too high for your body, and reducing the amount you take often resolves them.
Senna can also change the color of your urine to a yellowish-brown or reddish tint. This is harmless and stops once you discontinue the medication.
Risks of Long-Term Use
Senokot is meant for short-term use, generally no longer than two weeks without medical supervision. Extended use carries two main concerns.
The first is electrolyte imbalance. Prolonged stimulant laxative use can shift levels of potassium, sodium, and magnesium in your body. A severe imbalance can cause muscle spasms, twitching, or in rare cases, seizures. This risk is higher if you’re already dehydrated or have kidney problems.
The second is a condition called melanosis coli, where the inner lining of your colon turns dark brown or black. This happens because senna contains compounds called anthraquinones, and chronic exposure can damage cells in the colon wall, causing them to release a pigment called lipofuscin. Despite its alarming appearance during a colonoscopy, melanosis coli is not cancerous and carries no increased cancer risk. It reverses on its own within 6 to 12 months after you stop taking the laxative.
There’s a common worry that long-term use will make your bowels “dependent” on stimulant laxatives. While tolerance can develop over time (meaning you need a higher dose for the same effect), current gastroenterology guidelines recognize senna as a reasonable option even for chronic constipation when used under a doctor’s supervision.
Who Should Avoid Senokot
Senokot is not safe for everyone. You should avoid it or talk to a doctor first if you have:
- Intestinal obstruction: A blockage in the bowel means stimulating contractions could cause serious harm
- Severe stomach pain with nausea or vomiting: These symptoms may signal a condition like appendicitis that laxatives could worsen
- Inflammatory bowel disease: Crohn’s disease or ulcerative colitis can flare with stimulant laxative use
- Dehydration: Signs include dark urine, reduced urination, and strong-smelling pee
- Kidney or heart problems: The potential for electrolyte shifts makes monitoring important
Safety During Pregnancy and Breastfeeding
Senna is occasionally used during pregnancy, and there’s no evidence it causes harm to the baby. That said, other laxatives like fiber supplements and osmotic options have a longer safety track record in pregnancy, so they’re typically tried first. If those don’t work, senna remains an option worth discussing with your provider.
During breastfeeding, only tiny amounts of senna pass into breast milk, and these are unlikely to affect your baby. If you notice your baby feeding less than usual or developing diarrhea, that’s worth flagging to your midwife or doctor, but for most nursing parents, occasional Senokot use poses minimal risk.