Laxatives

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, such as ispaghula husk (Fybogel) and methylcellulose, absorb water and swell in the bowel, which softens and bulks up the stool. They are the safest laxatives for regular use, should be taken with plenty of water, and usually take effect within 2 to 3 days.

Osmotic laxatives, such as lactulose and macrogol (Movicol, Laxido), work by drawing water into the bowel to soften the stool. They are commonly prescribed on the NHS, take effect within 1 to 3 days, and work best when you drink extra fluids alongside them.

Stimulant laxatives, such as senna and bisacodyl (Dulcolax), stimulate the bowel muscle to contract and work within 6 to 12 hours. They are intended for short-term or occasional use, since regular long-term use can lead the bowel to become dependent on them.

Stool softeners, such as docusate sodium, soften the surface of the stool and are often combined with stimulant laxatives.

Enemas and suppositories are used rectally when oral laxatives are not sufficient. They act quickly, within 15 to 60 minutes, and are available from a pharmacy or on prescription.

How to use laxatives safely

Read the packet carefully and do not exceed the stated dose, allowing enough time for a laxative to work before taking another one. Drink plenty of water, especially when taking bulk-forming and osmotic types, and start with the gentlest option, such as a bulk-forming or osmotic laxative, before trying anything stronger. Ask a pharmacist if you are unsure which type of laxative suits you.

Lifestyle changes before laxatives

Before turning to laxatives, or alongside them, it helps to drink 6 to 8 glasses of fluid daily and eat more fibre from sources such as fruit, vegetables, pulses, wholegrain bread and cereal. Regular exercise, such as walking, also helps stimulate bowel movement. It helps to avoid ignoring the urge to go, allow unhurried time on the toilet, and try raising your feet on a low stool so your knees are above your hips.

See our constipation guide for more detail on these lifestyle measures.

When laxatives are not enough

See a GP if constipation persists for more than 3 weeks, if you find you need stimulant laxatives regularly, or if you notice blood in your poo or unexplained weight loss. Persistent abdominal pain, or a pattern of alternating constipation and diarrhoea that could suggest IBS or another condition, also warrants a GP assessment.

Laxatives treat the symptom of constipation but do not address underlying causes, which can include thyroid problems, certain medications, other bowel conditions, or, in older adults, more serious underlying disease.

Laxatives and other medicines

Some medicines can cause constipation as a side effect, including opioids, iron supplements, some antidepressants, and antacids containing calcium or aluminium. A GP may adjust your medicines or add a preventive laxative if you need to take opioids long-term.

Laxatives in special situations

Constipation is common in pregnancy, and bulk-forming and osmotic laxatives are generally considered safe to use, though it is best to ask a midwife or GP before using stimulant laxatives. Children should not be given laxatives without medical advice. Older adults are at higher risk of dehydration from laxative use, so osmotic laxatives are generally preferred under GP guidance.

Overuse of stimulant laxatives

Regular daily use of stimulant laxatives can make the bowel lazy, becoming dependent on stimulation in order to move. If you find you need senna or bisacodyl most days, see a GP for assessment and help with a longer-term plan.

When laxative use needs emergency help

Severe abdominal pain with an inability to pass stool or wind, vomiting, and a swollen or distended abdomen may indicate a bowel obstruction, which needs a 999 call rather than more laxatives.

Common questions about laxatives

What are the main types of laxatives?

The main types are bulk-forming laxatives such as ispaghula husk (Fybogel), osmotic laxatives such as lactulose and macrogol (Movicol), stimulant laxatives such as senna and bisacodyl (Dulcolax), and stool softeners such as docusate. Each type works differently, so a pharmacist or GP can help you choose the right one.

How long do laxatives take to work?

Bulk-forming laxatives usually take 2 to 3 days to work, while osmotic laxatives act within 1 to 3 days. Stimulant laxatives work faster, within 6 to 12 hours, and enemas or suppositories act quickest of all, within 15 to 60 minutes. Read the packet and allow enough time to pass before taking another dose.

Can I take laxatives every day?

Bulk-forming and osmotic laxatives can often be used regularly if needed, but stimulant laxatives are meant for short-term use, since the bowel can become dependent on them with long-term daily use. See a GP if you find you need stimulant laxatives regularly.

What should I try before taking laxatives?

Try increasing your fluids, fibre intake from fruit, vegetables and wholegrains, and physical activity first, along with establishing a regular toilet routine and not ignoring the urge to go. These lifestyle changes resolve many cases of constipation without any medication being needed.

Can laxatives cause dehydration?

Osmotic and stimulant laxatives increase the amount of water lost in stool, so it is important to drink plenty of fluids while using them. This is especially important for older adults and people taking diuretics.

Sources

• NHS — Laxatives
• NHS — Constipation