Quick answer
What is laxatives used for?
Laxatives treat constipation by softening stool, bulking it up, or stimulating the bowel. Most work within 1 to 3 days. Start with lifestyle changes — fluids, fibre, exercise — before laxatives. See a GP if constipation lasts more than 3 weeks, you have blood in poo, or unexplained weight loss.
When are laxatives used?
Laxatives treat constipation — difficulty passing stool, hard stools, or going less often than usual. They are widely available from pharmacies without prescription. They work, but lifestyle changes should come first — and constipation lasting more than three weeks needs GP assessment rather than repeated laxative use alone.
Types of laxatives
Bulk-forming laxatives — ispaghula husk (Fybogel), methylcellulose
- absorb water and swell, softening and bulking stool
- safest for regular use
- take with plenty of water
- effect in 2 to 3 days
Osmotic laxatives — lactulose, macrogol (Movicol, Laxido)
- draw water into the bowel to soften stool
- commonly prescribed on NHS
- effect in 1 to 3 days
- drink extra fluids
Stimulant laxatives — senna, bisacodyl (Dulcolax)
- stimulate the bowel muscle to contract
- work within 6 to 12 hours
- for short-term use — regular long-term use can cause dependency
- good for occasional relief
Stool softeners — docusate sodium
- soften stool surface
- often combined with stimulants
Enemas and suppositories — for rectal use when oral laxatives insufficient
- work within 15 to 60 minutes
- pharmacy or prescription
How to use laxatives safely
- read the packet — do not exceed the stated dose
- allow time to work before taking more
- drink plenty of water, especially with bulk-forming and osmotic types
- start with the gentlest option — bulk-forming or osmotic
- ask a pharmacist if unsure which type suits you
Lifestyle first
Before or alongside laxatives:
- drink 6 to 8 glasses of fluid daily
- eat more fibre — fruit, vegetables, pulses, wholegrain bread and cereal
- exercise regularly — walking helps bowel movement
- do not ignore the urge to go — allow unhurried toilet time
- raise feet on a low stool when on the toilet — knees above hips helps
See our constipation guide for more detail.
When laxatives are not enough
See a GP if:
- constipation persists more than 3 weeks
- you need stimulant laxatives regularly
- blood in poo or unexplained weight loss
- persistent abdominal pain
- alternating constipation and diarrhoea — possible IBS or other condition
Laxatives treat symptoms but do not address underlying causes — thyroid problems, medications, bowel conditions, or in older adults, more serious pathology.
Laxatives and other medicines
Some medicines cause constipation — opioids, iron supplements, some antidepressants, antacids with calcium or aluminium. A GP may adjust medicines or add preventive laxatives if opioids are needed long-term.
Special situations
Pregnancy — constipation is common. Bulk-forming and osmotic laxatives are generally safe; ask a midwife or GP before using stimulants.
Children — do not give laxatives to children without medical advice.
Older adults — higher risk of dehydration. Prefer osmotic laxatives under GP guidance.
Overuse of stimulant laxatives
Regular daily stimulant laxative use can make the bowel lazy — becoming dependent on stimulation to move. If you need senna or bisacodyl most days, see a GP for assessment and a long-term plan.
When to seek emergency help
Severe abdominal pain with inability to pass stool or wind, vomiting, and a distended abdomen may indicate bowel obstruction — call 999. Do not keep taking laxatives.
Common questions
- What are the main types of laxatives?
- Bulk-forming (ispaghula husk — Fybogel), osmotic (lactulose, macrogol — Movicol), stimulant (senna, bisacodyl — Dulcolax), and stool softeners (docusate). Each works differently — a pharmacist or GP helps choose.
- How long do laxatives take to work?
- Bulk-forming — 2 to 3 days. Osmotic — 1 to 3 days. Stimulant — 6 to 12 hours. Enemas and suppositories — 15 to 60 minutes. Read the packet and allow time before trying another dose.
- Can I take laxatives every day?
- Bulk-forming and osmotic laxatives can often be used regularly if needed. Stimulant laxatives are for short-term use — the bowel can become dependent with long-term daily use. See a GP if you need stimulants regularly.
- What should I try before laxatives?
- Increase fluids, fibre (fruit, vegetables, wholegrains), and physical activity. Establish a regular toilet routine — do not ignore the urge to go. These changes resolve many cases without medication.
- Can laxatives cause dehydration?
- Osmotic and stimulant laxatives increase water loss in stool — drink plenty of fluids while using them. This is especially important for older adults and people on diuretics.