This guide compares common options for adults. It does not supply a personal dose or instructions for bowel preparation before a procedure. Products, strengths and nonprescription availability vary between countries, so check the exact medicine in front of you.
Before you buy: is self-treatment appropriate?
Do not take a laxative for severe unexplained abdominal pain or vomiting; seek medical advice. Blood in stool also needs assessment. If symptoms are severe or you are becoming unwell, seek urgent care. Medicines may contribute to constipation, so include prescriptions, supplements and existing laxatives in your discussion with the pharmacist. [7]
Ask for advice first during pregnancy or breastfeeding, for a child, or if you have swallowing problems, inflammatory bowel disease, heart disease or take opioid painkillers. Some options may still be suitable, but the choice needs checking. [2]
What the chronic-constipation guideline can tell you
The 2023 joint AGA/ACG guideline addresses adults with chronic idiopathic constipation: persistent constipation without an identified underlying cause. Its drug recommendations do not automatically apply to a brief episode, opioid-related constipation or IBS with constipation. It helps explain the evidence for treatments after the clinical problem has been assessed. [1]
Psyllium: a bulk-forming option
Psyllium absorbs liquid and forms a bulkier stool that can be easier to pass. It can be useful to discuss when you want a fiber-based option. Powder must be mixed with the amount of liquid specified on its label; swallowing a dry dose is not an acceptable shortcut. [3]
Check before using it if you have difficulty swallowing, a history of intestinal blockage, or a medical restriction on fluids. Ask a pharmacist whether to separate it from other medicines, because some interactions require a gap. Seek help for new swallowing or breathing difficulty after taking it. [3]
Bulk-forming products generally take a few days to work. They are a poor match for someone expecting an immediate bowel movement. [2] Decide in advance how you will judge the result: easier passage matters as well as frequency.
Polyethylene glycol: retaining water in stool
Polyethylene glycol, usually abbreviated PEG and also called macrogol, is an osmotic laxative. It retains water with stool to make passage easier. PEG 3350 powder is mixed into liquid according to the product instructions. MedlinePlus gives an expected onset of two to four days, so lack of a same-day effect is not a reason to take extra. [4]
Possible effects include bloating, gas, nausea and cramping. Check with a professional if troublesome symptoms or diarrhea develop. Mention possible bowel-obstruction symptoms, including vomiting and significant pain or bloating, before taking it. [4]
PEG has a strong recommendation in the AGA/ACG guideline for adults with chronic idiopathic constipation. [1] This supports discussing it as an option; it does not override a particular product's label or a clinician's instructions.
Stimulants: usually faster, with specific instructions
Bisacodyl stimulates bowel activity. Oral tablets generally act within six to twelve hours, which is why some people take them in the evening. Tablets should be swallowed whole. Milk products and antacids can affect how they are used; follow the separation instructions in the leaflet or ask a pharmacist. [5]
Cramping and abdominal discomfort can occur. If there is no bowel movement after bisacodyl, seek advice instead of repeatedly taking more. MedlinePlus advises speaking to a doctor before taking oral bisacodyl for more than one week. [5]
The CIC guideline strongly recommends bisacodyl or sodium picosulfate for short-term or rescue use, and conditionally suggests senna. It defines short-term use for its evidence assessment as four weeks or less; this is not permission to extend an OTC label's shorter limit. Longer-term stimulant data remain limited. [1]
A clinician may include a stimulant in a planned regimen. Avoid assuming either that every repeated use causes permanent bowel damage or that an effective first dose proves indefinite self-treatment is safe.
Magnesium products need a kidney check
The CIC guideline conditionally suggests magnesium oxide, with very low certainty of evidence. Its finding cannot be assumed to cover every magnesium salt sold as a supplement. It advises avoiding magnesium oxide in renal insufficiency because magnesium can accumulate to unsafe levels. Ask before choosing a magnesium laxative if you have kidney disease. [1]
Does a stool softener work as well?
Docusate is sold as a stool softener, but the name alone cannot tell you whether it is the best treatment. In a randomized study of 170 adults with chronic idiopathic constipation, psyllium improved stool water content and several bowel measures more than docusate. The treatment period was only two weeks, and the first author was affiliated with a manufacturer. [8]
That is a limited comparison, not proof that docusate never has a role. If it is not helping, describe the actual problem to a pharmacist instead of assuming that increasing a “gentle” product is the next step. If it was prescribed for a specific reason, review that plan with the prescriber.
Enemas are not automatically a safer shortcut
Sodium phosphate products deserve special caution, including enemas. The FDA warns that exceeding the recommended amount can cause serious dehydration, electrolyte disturbances and kidney or heart injury. Do not use more than one dose in 24 hours, even if the first produces no bowel movement; contact a healthcare professional. [6]
Risk is higher with dehydration, kidney disease, some bowel conditions and certain medicines, including diuretics, ACE inhibitors, ARBs and NSAIDs. Adults over 55 should also get advice before use. Reduced urination, unusual drowsiness or swelling after a phosphate product needs immediate medical attention. [6]
Turn the packet instructions into a clear plan
- Identify the active ingredient and formulation. A tablet, powder, suppository and enema can have very different instructions.
- Check the expected onset before deciding that treatment failed. Waiting for an expected effect is different from waiting through worsening symptoms.
- Follow the stated amount, frequency, mixing instructions and maximum self-treatment period. Do not add a second laxative without checking the combination. [7]
- Write down the ingredient, use and response. Include cramping, diarrhea and whether you still felt unable to empty.
- Ask what to do if symptoms return. A useful plan includes both the treatment and the point at which to seek another assessment.
For medicines bought without a prescription, NHS guidance advises stopping when constipation improves and not continuing beyond seven days. Your product may specify a shorter period. Persistent or recurrent need deserves review; a clinician may recommend an ongoing regimen for a diagnosed condition. [2]
Bring the packets or clear photos of their labels to that conversation. “I used this ingredient for this long, and it softened stool but did not make emptying easier” gives the clinician a concrete starting point for choosing what comes next.
- Related reading: Constipation: What Helps, What to Avoid, and When to Get Care.
References for the Curious Minds
- AGA/ACG (2023): Pharmacological Management of Chronic Idiopathic Constipation
- NHS: Laxatives
- MedlinePlus: Psyllium
- MedlinePlus: Polyethylene Glycol 3350
- MedlinePlus: Bisacodyl
- FDA: Sodium Phosphate Laxative Safety Communication
- MedlinePlus: Constipation Self-Care
- McRorie et al. (1998): Psyllium Compared With Docusate Sodium
