Laxatives are medicines that help you pass stool. They come in a few main classes that work in different ways: bulk-forming (fiber supplements), osmotic, stool softeners, and stimulants. Cleveland Clinic describes bulk-forming laxatives as generally the gentlest and often the best to try first, unless a provider recommends something else. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) says stimulants should be used only if constipation is severe or other treatments have not worked. Any laxative that you need for more than a short stretch, or constipation that comes with warning signs, is a reason to talk to a clinician rather than keep self-treating.
By MeridianMedicalCentre.com Health Research Team
Try the basics before a laxative
NIDDK says most constipation can be treated at home, starting with food, fluids, and movement. Its advice is to eat more high-fiber foods, drink plenty of fluids if you add fiber, get regular physical activity, and try to have a bowel movement at the same time each day. NIDDK puts adult fiber needs at 22 to 34 grams a day, depending on age and sex.
Mayo Clinic makes the same point: if constipation continues after these changes, a mild laxative may be the next step. Habits are also the focus of our look at a viral claim, the “7-second poop trick”, which separates the ordinary habits behind it from the promise of an instant result.
The four main laxative classes, side by side
Onset times and active-ingredient examples below come from Cleveland Clinic. Mechanisms and side effects come from Mayo Clinic unless noted. Individual results vary, and the label on your product is the final word on dose and timing.
Bulk-forming laxatives (fiber supplements)
- How they work: they absorb water to form soft, bulky stool, which prompts the intestinal muscles to contract. Common active ingredients include psyllium, methylcellulose, and polycarbophil.
- Typical onset: 12 hours to three days.
- Common side effects and cautions: bloating, gas, and cramping. They can make constipation worse if taken without enough water. Cleveland Clinic lists dehydration as a risk with this class, which is why labels tell you to drink extra fluid.
Osmotic laxatives
- How they work: they draw water into the colon so stool passes more easily. Examples include polyethylene glycol and magnesium hydroxide.
- Typical onset: one to three days. Saline types, a kind of osmotic laxative, can act faster, from 30 minutes to six hours.
- Common side effects and cautions: bloating, cramping, diarrhea, nausea, gas, and increased thirst. Cleveland Clinic lists dehydration as a risk here too, so follow the fluid instructions on the label.
Stool softeners
- How they work: they add moisture to stool so it can pass without straining. Docusate is the usual active ingredient.
- Typical onset: 12 hours to three days.
- Common side effects and cautions: Mayo Clinic lists electrolyte imbalance with long-term use.
Stimulant laxatives
- How they work: they trigger rhythmic contractions of the intestinal muscles to move stool out. Common active ingredients include bisacodyl and senna.
- Typical onset: six to 12 hours.
- Common side effects and cautions: belching, cramping, diarrhea, and nausea. Senna and cascara products can discolor urine. Cleveland Clinic warns that using stimulants longer than directed can reduce muscle tone in the colon and worsen constipation. Mayo Clinic says stimulant laxatives may be harmful during pregnancy.
Other forms you may come across
Laxatives also come as suppositories and enemas, which act within about 15 minutes to an hour according to Cleveland Clinic. That source notes they carry a greater risk of diarrhea and cramping. Mayo Clinic lists rectal irritation as a possible side effect of suppositories. NIDDK also lists lubricants such as mineral oil among over-the-counter options.
Some products combine two types, such as a stimulant and a stool softener. Mayo Clinic says combination products do not necessarily work better than single-ingredient ones and may be more likely to cause side effects, so read the label to know exactly what you are taking.
If over-the-counter options are not enough, clinicians can prescribe other medicines. NIDDK lists lubiprostone, linaclotide, plecanatide, and prucalopride as examples. Those decisions belong with a prescriber.
Checklist: see a clinician instead of self-treating
Mayo Clinic advises calling your healthcare team right away if you have any of the following:
- Severe stomach cramps or pain
- Unexplained changes in your bowel pattern
- Severe diarrhea
- Bloody stools or rectal bleeding
- Constipation that lasts longer than seven days even with laxative use
- Weakness or unusual tiredness
- Dizziness
If you are having a medical emergency, call 911 or your local emergency number rather than relying on a website. Our Medical Disclaimer says the same.
Check with a clinician before using a laxative in these situations:
- You are pregnant. Mayo Clinic says bulk-forming laxatives and stool softeners are generally considered safe in pregnancy, but stimulants may be harmful, so ask first.
- The person is a child. Mayo Clinic says not to give laxatives to children under age 6 without a healthcare professional's recommendation. Cleveland Clinic advises giving a child a laxative only if their pediatrician recommends it.
- You take prescription medicines. Mayo Clinic says laxatives can interact with many medicines, including certain antibiotics, heart medicines, and bone medicines. Cleveland Clinic also advises talking with your provider first if you take a prescription medication.
- You may have a blockage or another condition behind the constipation. Mayo Clinic says laxative use can be dangerous if constipation is caused by a serious condition such as a bowel blockage. Cleveland Clinic adds that laxatives treat the symptom, not the cause, and can delay a diagnosis.
- You are breastfeeding. Mayo Clinic says some ingredients may pass into breast milk, so talk to a professional first.
- A medicine or supplement may be causing the constipation. NIDDK advises talking with your doctor, and not stopping or changing any medicine on your own.
Using a laxative more safely
- Follow the label. Cleveland Clinic warns that it is possible to overdose on laxatives, including over-the-counter ones, so do not take more than the instructions or your provider say.
- Be patient. Gentler types can take a few days. If one is not working, Cleveland Clinic says to reach out to a provider rather than take more.
- Keep it short-term. Mayo Clinic says using laxatives too much for weeks or months can make constipation worse by reducing the colon's ability to contract.
- If you feel you cannot go without one, NIDDK and Mayo Clinic both advise talking to your doctor about slowly stopping. NIDDK says the colon should start moving stool normally again over time.
What to do next
Start with fiber-rich foods, fluids, and activity. If you add a laxative, Cleveland Clinic describes bulk-forming products as often the best to try first, unless your provider recommends a different type. Mayo Clinic suggests talking to your healthcare team before choosing one, because they can help decide the safest kind for you. Keep use short, watch for the warning signs above, and contact a clinician if a laxative does not work or you find yourself constipated frequently.
Sources
Sources checked October 3, 2026. Each page's own last-updated date is shown, and clinical guidance may have changed since.
- Treatment for Constipation, National Institute of Diabetes and Digestive and Kidney Diseases (page last reviewed May 2018).
- Nonprescription laxatives for constipation: Use with caution, Mayo Clinic (January 26, 2024).
- Laxatives: What They Do, Types and How To Use Them, Cleveland Clinic (medically reviewed; last updated July 2023).
This article is general information from an independent editorial publication. It is not medical advice and does not replace guidance from your doctor or pharmacist. This page contains no affiliate links and recommends no products.