Title: Lower GI Tract Problems

Key words: Laxatives, anti-diarrhoea, irritable bowel syndrome,

Date: Aug 2000

Category: 8. The Gut

Type: Article

Author: DJE Candlish

Lower GI Tract Problems


Products for the treatment of problems affecting the lower digestive tract (GI tract) are a mainstay of the typical pharmacy. Laxatives, anti-diarrhoea medicines and products for irritable bowel syndrome (IBS) sell consistently throughout the year to a wide range of customers. These products generally have a good safety profile when used as self-treatment by pharmacy customers for relatively minor complaints.

However, the symptoms of these minor conditions are often similar to the symptoms of more serious, even life threatening conditions and it is important to be aware of this. The pharmacist and pharmacy assistants can play an important role in community medicine by identifying customers who need medical advice or help rather than an OTC medicine.

Patients being treated by their doctor for lower GI tract conditions may ask the pharmacist for advice on how to take the medicine they have been prescribed. They may also ask whether or not it is safe to take OTC medications, in addition to their prescription medicine. OTC medications can provide valuable extra relief of symptoms.




Overview of the GI tract

Normal function of the GI tract


Problems of the lower GI tract

Anal fissure

Colic/infant colic

Duodenal ulcer

Irritable bowel syndrome (IBS)

Crohn’s disease and ulcerative colitis

Bowel cancer

Gallbladder disease


Haemorrhoids (piles)

Pruritus ani


Coeliac disease

GI Spasm

Management of lower GI tract problems



Nausea and vomiting





Overview of the lower GI tract

The gastrointestinal (GI) or digestive tract takes in foods and liquids, extracts from them what the body requires for energy and growth and eliminates what is left from the body. These functions are known as ingestion, digestion, absorption and elimination. Each involves specific parts of the tract:

The main functions of the lower GI tract, which consists of the small and large intestines, rectum and anus are absorption and elimination. Other body systems, such as the urinary tract and skin are also involved, to a limited extent, in elimination of some of the body's waste through urination and sweating.

The small intestine is divided by structure and function into the duodenum, jejunum and ileum. Inside the small intestine, the surface area is increased by circular folds and villi, small (1mm high and 0.1mm wide) finger-like projections. The villi, in turn, consist of epithelial cells with many microvilli, to further increase the surface area for digestion and absorption. Almost all of our nutritional needs are absorbed in the small intestine.

The main digestive juices of the small intestine are bile and pancreatic juice. Bile is formed in the liver and stored in the gall bladder until the presence of fatty food in the intestine stimulates its release. Bile is involved in the breakdown and/or absorption of fats and fat soluble vitamins. The pancreas produces amylase to break down carbohydrates, lipase to break down fats and trypsinogen. This is activated in the lumen of the small intestine by enterokinase, to form trypsin, which breaks down protein. The intestinal mucosa produces enterokinase, mucus and sodium bicarbonate ions to neutralise stomach acid.

The large intestine consists of five parts, the caecum (which has an appendix), the ascending colon, transverse colon, descending colon, sigmoid colon and the rectum which ends at the anus, the valve or sphincter through which faeces are released during defaecation. The large intestine does not contain villi or microvilli and only water, vitamins and some minerals are absorbed here.

Normal function of the GI tract

The GI tract is best thought of as a smooth muscle tube running from mouth to anus, with sphincters or valves in various places along the way. The tube has a lining composed of the mucosa and submucosa and an outer covering known as the serosa. Between these there are two layers of smooth muscle, an inner circular layer and an outer longitudinal layer.

These are controlled by the autonomic nervous system (ANS), under the overall control of the central nervous system (CNS). This is why strong emotions such as fear and stress can affect the GI tract, causing diarrhoea before exams, for example.

In the gut or small intestine, contraction of the circular smooth muscle constricts the gut (reduces diameter), while contraction of the longitudinal muscle shortens it. Food is mixed with digestive juices by rhythmic relaxation and contraction of short sections of these two layers in a process called segmentation.

Food is moved along the tube by a co-ordinated wave of smooth muscle contraction squeezing it towards the anus, in a process called peristalsis (see Figure). Vomiting occurs if the direction of peristalsis is reversed. Diarrhoea results if peristalsis is too rapid or powerful and water is not reabsorbed to the normal extent in the large intestine. Constipation is due to a number of factors, which are explained later.


The removal of solid waste matter (faeces or ‘stools’) from the GI tract is called defaecation. The process involves stretch receptors responding to faeces entering the sigmoid colon of the large intestine and the rectum. The receptors signal the brain that storage space is being used up and that evacuation of the bowel is needed.

Muscular valves in the anus (the anal sphincters) prevent faeces leaving the rectum until a conscious decision is made to release them by going to the toilet. When this happens, the valves relax, the colon and rectum contract and the faeces are expelled. Conscious control of the sphincters is learnt at an early age during ‘potty training’. Constipation, or retention of faeces, develops when something interferes with this process.

Problems of the lower GI tract

The problems that can occur in this section of the GI tract range from the trivial (indigestion) to the life threatening (bowel cancer). It is obviously important to differentiate between the minor conditions and the more serious ones, but this can be difficult, because the symptoms are often similar at first.


Common conditions

The more common of the conditions that can affect the lower GI tract include:

These conditions will be described briefly, along with treatment options, in the following pages. The most common problems of the lower GI tract can either be the symptoms of a medical condition or can occur by themselves. These include:

Anal fissure

An anal fissure is a crack or split in the skin or mucosa around the anus, which exposes the sensitive internal tissues below. This can be very uncomfortable, even painful, especially when passing faeces. Bright red spots of blood may be seen on toilet paper or the faeces if the fissure is deep enough to bleed. Anal fissures are associated with haemorrhoids and constipation. The pain can add to the problem of constipation, by discouraging defaecation.

The treatment for anal fissure involves good hygiene, with regular bathing or showers, plus frequent application of a soothing, antiseptic cream or ointment, such as those used to treat haemorrhoids. The cream or ointment should be reapplied whenever the bowel is evacuated. Severe anal fissures may even need minor surgery.

Colic/infant colic

Colic is a distinctive type of abdominal pain. People affected by colic tend to lie down and try to draw their legs up to their chest to relieve the pain. The pain itself is severe, but intermittent. It is caused by powerful contractions of the smooth muscle in the intestines. Colic occurs in response to either inflammation (as in food poisoning), obstruction (e.g. when a gallstone blocks the bile duct) or distension (swelling) due to trapped gas.

Colic often responds to peppermint oil, which is thought to have a direct relaxing effect on the intestinal smooth muscle. Other muscle relaxants such as alverine and mebeverine may also be used. Activated dimethicone or simethicone has also been found to help when the colic is due to distension resulting from trapped gas. These are defoaming agents which break down or coalesce bubbles, allowing the gas in them to be removed by belching.

Infant colic is a very common problem in the first few months after birth. Affected babies draw their legs up to their chest in the characteristic way of colic and cry loudly while the pain lasts. Infant colic may be due to air swallowed by the baby during feeding becoming trapped in the intestines, causing painful distension.

Apart from 'winding' or 'burping' the baby to help it remove gas by belching, the traditional treatment for infant colic is gripe water. This contains sodium bicarbonate, which helps the baby to get rid of the excess gas through belching and also helps reduce acidity in the GI tract. Traditional gripe water also contained alcohol, which helped to soothe the baby off to sleep. More modern remedies for infant colic contain activated dimethicone or simethicone.

Duodenal ulcer

A duodenal ulcer is an area on the wall of the duodenum that has been temporarily stripped of its protective lining. This occurs when the balance between 'defensive' factors protecting the lining (mucus, bicarbonate, fast cell turnover) and 'aggressive' factors attacking it (gastric acid and digestive enzymes) is disturbed. A bacterium, Helicobacter pylori, is now believed to play an important role in disturbing this balance.

Duodenal ulcers are more common than gastric ulcers (see Module 6) and affect younger people. People who smoke are at much greater risk of developing ulcers than non-smokers. Smoking also delays the healing of ulcers. Alcohol, especially in the form of spirits, is another aggravating factor for duodenal ulcers.

Ulcers typically cause pain. The pain described by someone with a duodenal ulcer is quite distinctive. It is often described as a gnawing, hunger-type pain. It is brought on by hunger and relieved by eating and often wakes the sufferer during the night. It tends to occur in cycles over several years, with weeks or months without pain followed by periods of severe pain. Many people with ulcers also complain of dyspepsia – a generalised feeling of discomfort in the abdomen which is commonly called indigestion.

Because of the rich blood supply to the lining, ulcers can bleed profusely. This can be life threatening if a major blood vessel or the entire thickness of the gut wall is perforated. Small, undetected ulcers can cause anaemia. Blood from an ulcer appearing in the stools or faeces makes the faeces look black and tarry. This is known as malaena. Fresh (red) blood in the faeces indicates damage or injury lower down the GI tract, such as haemorrhoids, anal fissures or bowel cancer.

Ulcers must be treated by a doctor, as they can cause severe bleeding and even death, if not treated correctly. Treatment is based upon reducing the acidity of the gastric contents until the damaged mucosa heals by itself, usually a fairly rapid process.

In the UK, cimetidine, ranitidine and famotidine, which used to be prescription only medicines (POM), are now available OTC. These drugs reduce the amount of acid the stomach secretes during digestion. At OTC dose levels, they help to reduce acid-related indigestion. At prescription dose levels, a few weeks treatment should allow healing to take place.

Overuse of these drugs at any dose level may mask the symptoms of gastric or bowel cancer and delay diagnosis. However, people whose ulcers have healed are often prescribed low doses as maintenance therapy, to prevent recurrence of their ulcer.

Antacids, which neutralise gastric acid on contact, can also help ulcer sufferers, on the advice of a doctor. Antacids are usually based on magnesium salts (carbonate, trisilicate or hydroxide) or aluminium hydroxide. They are available in tablet or liquid form.

Irritable bowel syndrome (IBS)

This is a chronic and variable disease which can be difficult to diagnose and treat. A range of symptoms can present and diagnosis is usually made when four or more symptoms occur with no other obvious cause. These symptoms include:

Once the diagnosis has been made by a doctor, OTC medicines can be very helpful in relieving symptoms. Bulk laxatives and increased dietary fibre can help constipation in sufferers, but can also cause bloating and trapped wind. When diarrhoea is the problem, loperamide can help. Antispasmodic drugs, such as hyoscine, mebeverine and alverine may help some people as a specific OTC remedy for irritable bowel syndrome. They are not suitable for children under 12 or for pregnant or breastfeeding women.

Peppermint oil in special coated capsules (enteric) is said to have a direct beneficial effect on the muscles of the colon. These capsules do not release their contents until they are in the intestines.

Pharmacy customers with IBS should be advised to avoid beans, peas and cabbage, because these are gas-producing foods. Plain live yoghurt can help to normalise the gut contents. Exercise and relaxation techniques can reduce stress and hypnotherapy may also be of help.

Irritable bowel syndrome is often associated with psychological problems, such as depression, anxiety and stress. A history of chronic and intermittent bowel symptoms in a young or middle aged patient suggests this diagnosis.

It is important to distinguish irritable bowel syndrome from other causes of bowel disturbance, abdominal pain and loss of appetite. Bloody stools, weight loss and sudden changes in bowel habits need medical investigation, in case they are due to cancer.

Crohn's Disease And Ulcerative Colitis

These conditions are classed as chronic non-specific inflammatory bowel diseases. Their causes are not fully understood, but they generally affect young adults, causing severe discomfort but rarely resulting in death. They cause inflammatory changes to the lining of the GI tract which can result in permanent damage.

The major symptoms are abdominal pain, loss of appetite and regular attacks of urgent diarrhoea. Treatment involves a range of options, including surgery in severe cases. Severe cases may require an ileostomy, the surgical formation of an artificial opening through the abdominal wall into the ileum so that the intestinal contents are discharged into a disposable bag without passing through the colon. Corticosteroids are the most effective treatment for Crohn's disease, while sulphasalazine is the mainstay for ulcerative colitis, which is generally less severe and more localised to the large intestine and rectum than Crohn's disease. Medication may also be used to help control diarrhoea, on the advice of a doctor.

Bowel Cancer

This is one of the most common cancers, affecting about 30 people in 100,000 in the UK. About half of all bowel cancers develop in the rectum. Symptoms include loss of appetite, weight loss, tiredness, feelings of fullness after eating small amounts and sometimes nausea and vomiting. Pain and bleeding occur in the more advanced stages.

Diagnosis can be confirmed by endoscopy (internal visual examination) and biopsy (microscopic examination of tissue) or barium enema and X-ray. Treatment involves surgical removal of all affected tissue in the colon. This may require a colostomy, the surgical formation of an artificial opening through the abdominal wall so that the intestinal contents can be drained off into disposable bags instead of passing through the colon to the rectum and anus. Pharmacists and doctors are aware of the danger that self-medication with OTC products can mask the early symptoms of bowel cancer.

Gallbladder disease

Gallstones are semi-solid objects composed of cholesterol and mineral salts such as calcium, plus cellular debris from within the gallbladder. The stones develop when the concentration of cholesterol in bile is too high, relative to the bile acids and phospholipids which normally keep it in solution. Bile is the digestive juice formed by the gallbladder.

Gallstones cause severe pain, described as biliary colic. The pain is usually felt over the gallbladder, but can spread across the abdomen. It can be intense and last for several hours at a time.

Treatment involves a range of substances, including oral bile acids, that can soften or dissolve the stones and clear any blockage of the gallbladder. Surgical removal of the stones or even the gallbladder itself may also be needed. The only place for OTC medication is in pain relief and then only on the advice of a doctor.


Pancreatitis is an inflammatory condition of the pancreas, which can be very serious. It is often caused by gallstones in the bile duct forcing bile into the pancreatic duct. Alcoholic binges can cause acute relapses of chronic pancreatitis.

Pancreatic pain typically starts quite suddenly, after a rich meal or a drinking bout. It may be accompanied by sweating, vomiting and shock, leading to collapse in severe cases. Treatment is supportive, with intravenous fluids and pain relief. In very severe cases, surgical removal of the affected tissue may be needed. OTC medication is unlikely to be involved.

Haemorrhoids (piles)

These are irregular shaped (knobbly) swellings on veins inside the anus, which can cause itching and/or pain. They can hang down outside the anal canal during defaecation, or permanently, in some cases, when they are called external haemorrhoids. They can make passing a stool very painful. Spots of bright red blood may be seen on toilet paper, due to localised bleeding.

Haemorrhoids are associated with constipation. Straining to pass a stool increases the pressure in anal veins and this can either be the cause of the haemorrhoids or just make them worse. Haemorrhoids are also common during pregnancy, often clearing up after the birth.

Avoiding or eliminating constipation by increasing dietary fibre intake or using bulking agents or osmotic laxatives is an important part of treatment. A range of OTC ointments, creams and suppositories is also available, to reduce the discomfort. They should be applied morning and night and used after every bowel movement. Severe haemorrhoids may need to be treated surgically.

The medications used to treat haemorrhoids include:

Some products contain combinations of one or more of these ingredients. Anti-inflammatory creams and ointments reduce the pain, redness, swelling and temperature of the affected area. Hydrocortisone should only be used for short periods and should be avoided altogether in pregnancy. The antiseptics help prevent infection and encourage healing in the haemorrhoidal area.

Astringents shrink haemorrhoids, harden the surrounding skin, dry up soggy areas of damaged skin or mucous membrane and reduce minor bleeding. Local anaesthetics simply relieve the pain of the haemorrhoids. They should not be used long-term as they can cause sensitisation (irritation).

Zinc oxide is widely used as a base for creams and ointments because it is soothing and mildly antiseptic.

Pruritus ani

Pruritus ani or anal itching may be a sign of either haemorrhoids or threadworm infection. It is also caused by liquid paraffin, a lubricant laxative (see later). Some haemorrhoid creams and ointments will help to reduce the itching even when there are no haemorrhoids present. Threadworm must be treated promptly to avoid it being passed on to others.


Infestation with threadworms is a common problem in young children. They live in the gut but females crawl out through the anus at night to lay their eggs upon the anal skin. This causes itching and irritation.

When the affected child scratches, the eggs can transfer to the hands, especially under the fingernails. They can then be passed on to other children, who become infected themselves if they swallow the eggs. The eggs can be picked up from clothes, furniture, toilet seats and so on.

Threadworms are seen as small white threads, up to half an inch long, around the anus or in the faeces. They may not cause symptoms at first, but more often they cause severe itching, especially at night, which can lead to skin damage from scratching and tiredness from lack of sleep.

Although a relatively trivial problem, many people find threadworm infection is embarrassing and unpleasant. Fortunately, there are effective treatments, such as mebendazole and piperazine. Mebendazole is given as a single dose, which is usually effective if hygiene measures are taken. The treatment may have to be repeated a few weeks later, if re-infection occurs. Mebendazole can cause diarrhoea and abdominal discomfort.

Piperazine is available as a syrup which can be taken for seven days or as a powder with senna (a laxative), taken in two doses two weeks apart. The laxative helps to expel the worms, which are paralysed by piperazine. Side effects include nausea, vomiting, abdominal pain and allergic reactions.

To prevent re-infection, the whole family of the child involved should be treated, all at the same time. Hygiene measures, such as washing the hands after every bowel movement, keeping children’s finger nails short and trying to stop them putting their hands in their mouths is recommended. Sheets, clothes and nightclothes should be changed and washed daily until the infection is definitely over.

Coeliac disease

Coeliac disease is a condition in which gluten affects the absorption of nutrients from the intestine, resulting in weight loss, diarrhoea, vomiting and tiredness. Gluten is a substance present in wheat, rye, barley and oats.

The only effective treatment for coeliac disease is avoidance of gluten, so a range of gluten-free foods has been developed. Some of these can be obtained on prescription, others can simply be purchased from the pharmacy. Sufferers also need to know whether or not any medicines they receive contain gluten. Their doctor or pharmacist can advise on this and recommend an alternative, if necessary.

GI spasm

While spasm of the intestines is a symptom of several conditions, such as colic and irritable bowel syndrome, it can also occur by itself. This may be due to air swallowed with food causing distension, which can trigger smooth muscle contraction. Treatment involves relaxing the muscles in spasm. A range of suitable products is available, containing either peppermint oil, hyoscine, mebeverine or alverine as muscle relaxants or antispasmodics.

Management of lower GI tract problems

The range of problems associated with minor lower GI tract conditions is generally limited to pain, dyspepsia, nausea/vomiting, diarrhoea, constipation, flatulence and wind. Depending how severe they are, these problems can be helped by appropriate use of OTC medication.


Abdominal pain should always be taken seriously. As you have seen, it can indicate a range of potentially serious conditions. If the cause is known and being treated, then a doctor may recommend an OTC analgesic, such as paracetamol, to relieve the pain itself. However, in general, abdominal pain is best relieved by treating the cause of the pain, whether it be inflammation, distension or muscle spasm.

Aspirin and ibuprofen should be avoided because they can irritate the GI tract lining. For more severe pain, a codeine/paracetamol combination product may be needed. Codeine should be avoided, however, if constipation is already present or would be likely to worsen the situation.


Dyspepsia, or indigestion, is a broad term that may be used to describe any discomfort associated with eating, such as pain, belching, heartburn, nausea, vomiting, distension and flatulence. People with benign duodenal ulcers may find that eating relieves their dyspepsia, but for most upper GI tract disorders, eating makes it worse.

Dyspepsia may be due to intolerance of fatty foods, or to excessive air being swallowed with the food. Rushed, irregular meals, eating too late at night, eating too much, smoking, alcohol and spicy foods are other common causes of dyspepsia. Stress and worry can bring on symptoms or make them worse.

Advice on dealing with dyspepsia includes improving lifestyle and diet, avoiding foods that are known to cause problems and eating in a more relaxed, unhurried way. Stopping smoking or reducing the amount smoked can also help.

Bismuth compounds are sometimes included in indigestion remedies. They are thought to coat the stomach and intestinal walls, protecting against irritants. Avoiding use of preparations containing aspirin, ibuprofen and iron is recommended, as these are known irritants. Certain herbal remedies, containing dill or cardamom are also helpful in relieving dyspepsia.


Nausea and vomiting

There are many causes of nausea and vomiting, some food-related, others not (see Table 1). Those involving the lower GI tract include peptic ulcer (i.e. stomach or duodenal ulcers), cancer and blockage and obstruction of the intestinal tract. The vomiting induced by uncomplicated peptic ulcers can relieve the ulcer pain for a while, due to the elimination of excess gastric acid from the body.

Most drugs to reduce nausea and vomiting are available on prescription only. Medicines containing bismuth salts may help with mild nausea while antihistamines and anticholinergics help in travel sickness.

Table 1 Causes of vomiting

Causes of vomiting



(due to conditions affecting the brain)


raised pressure inside skull

drug abuse (alcohol, opiates, etc.)


(due to inner ear problems)

travel sickness


(due to disorders of metabolism)




(see this module for details)

peptic ulcer

irritable bowel syndrome


Any situation where physical problems have been ruled out


Diarrhoea is a very common problem, resulting in production of loose, watery stools. It may be a short term problem or a symptom of a more chronic or intermittent condition. Short term diarrhoea can be caused by bacteria, as in 'food poisoning' due to eating contaminated food, or as part of a viral infection. It can also be caused by medicines (e.g. antibiotics) and by antacids containing magnesium.

This type of diarrhoea is usually self-limiting and rarely requires treatment, other than increasing the intake of fluids to allow for the extra fluid being lost in watery faeces. This is most important for babies, who can easily become dehydrated.

More persistent diarrhoea can cause imbalances of the salts (electrolytes) in the body, which may need treatment. In developing countries, diarrhoea due to chronic infection often causes these imbalances, causing the death of many children and elderly people every year. A simple solution of salt and glucose could save their lives. In the UK, sachets of salt and glucose are available OTC for anyone with severe diarrhoea.

In the western world, inflammatory disorders such as Crohn's disease and ulcerative colitis are more likely to be the cause of persistent diarrhoea. Bowel cancers, too, can cause sudden changes of bowel habit resulting in diarrhoea, often with blood in the faeces, looking black and tarry.

For acute diarrhoea, a number of drugs can help by slowing down the peristaltic movements of the gut. They include loperamide and low doses of morphine. Morphine is traditionally combined with kaolin, a powdery aluminium salt, either in liquid or tablet form. Codeine is not recommended as an OTC antidiarrhoeal in the UK, but it can help, as it is known to cause constipation in normal individuals.


Constipation is the retention of faeces, which may be due to a number of factors. In developed countries, constipation is a major problem, especially in the elderly. This may be due to the lack of roughage or fibre in the typical western diet, particularly in so called slimming diets.

Lack of physical activity, low fluid intake, old age, illnesses like depression and underactive thyroid glands and many medicines, especially analgesics containing codeine and other opioids are other common causes. Drugs that can cause constipation:

Prolonged retention of faeces reduces the sensitivity of the stretch receptors in the colon and rectum. These then send fewer, weaker signals to the brain to indicate their fullness and the urge to go to the toilet is weakened. Eventually, the build-up of faecal matter can stretch the colon (megacolon) or rectum (megarectum).

As water is reabsorbed into the body from the colon and rectum, the faeces can also become hard and dry (impacted) becoming both painful and difficult to remove.

Treatment for constipation is as varied as its causes. Exercise, extra fibre and fluid in the diet will help, but often laxatives are needed to stimulate the passing of stools, especially when the faeces are impacted. An enema, or anal infusion of liquid, may also be needed, but advice should be taken on this.

The best way to avoid constipation is to eat a high fibre diet with plenty of fluids. The best sources of dietary fibre are:

Laxatives are useful when dietary measures fail or when someone occasionally goes two or three days longer than usual without a bowel movement. They should not be used on a regular basis or 'just in case' as they can make the bowels even more sluggish. Some elderly people take laxatives regularly because they mistakenly believe they should have a bowel movement every day.

Some people, especially younger women with anorexia, use laxatives as part of a crash diet, aimed at losing weight fast. This can be dangerous. The muscles in the bowels can stop working properly, causing constipation, or the electrolyte balance of the body can be disturbed, just as in severe diarrhoea. Pharmacists and their assistants need to advise such customers against misusing laxatives in this way.


Types of laxative

Bulk forming laxatives

These include bran, psyllium ispaghula husk, methylcellulose and sterculia. They work by absorbing water and swelling to form a gel. This retains water in the faeces, avoiding impaction and making evacuation of the faeces easier. These laxatives also help people with diarrhoea, by bulking up their stools. The increased stool bulk stimulates the bowel in constipated individuals. These laxatives must be taken with plenty of fluid.

Emollient laxatives

These include docusate sodium and docusate calcium. These aid mixing of aqueous and fatty substances in the intestines, softening the stools and promoting defaecation. They can take effect in as little as 12 hours but may take several days. The high sodium or calcium content makes them unsuitable for people with poor kidney function.

Lubricant laxatives

These include liquid paraffin and mineral oil. They work by coating the stools and preventing reabsorption of water in the large intestine. This keeps the stools fairly soft and easy to evacuate. Lubricant laxatives may take only a few hours to work. Liquid paraffin is no longer recommended, however, as it can damage the lungs, cause vitamin deficiency and irritate the anal area.

Saline laxatives

These include magnesium salts (e.g. Epsom salts) and sodium phosphate. The magnesium or sodium ions draw water into the colon, increasing the volume of the faeces and increasing pressure within the colon and rectum, which stimulates defaecation. These laxatives are only for relief of acute constipation and are not for longer term use. They are unsuitable for people with impaired kidney function. They take 1-6 hours to work.

Hyperosmotic laxatives

These include glycerin, lactulose and lactitol. These laxatives retain water in the bowel and faeces. Lactulose is broken down to acidic substances by bacteria in the colon. The acidity stimulates defaecation. Glycerin works within 15-30 minutes. Lactulose can take up to three days.

Stimulant laxatives

These include bisacodyl, aloin, cascara, phenolphthalein and senna. They are thought to work by stimulating water and electrolyte secretion into the gut, softening stools and easing defaecation. Regular use can disturb the electrolyte balance of the body, so these laxatives are best used occasionally, for short periods only. They work fairly quickly, within 24 hours or so.


Flatulence is a broad term, used to describe the discomfort of gas or 'wind' trapped in the stomach and intestines. The gas may simply be air swallowed with food and drink or it may be due to fermentation within the intestines.

Flatulence can be helped by ‘health salts’, which form a fizzy antacid drink when mixed with water. Drinking this can make belching, or eructation, of the excess gas easier, which reduces the discomfort. Breaking wind, in a similar way, releases trapped flatus (gas) through the anus. Health salts contain large amounts of sodium, so they should be avoided by people with poor kidney function. Herbal remedies containing cardamon, dill or capsicum can also be effective in helping gas to be passed out of the system.

Other products available for flatulence are similar to those for dyspepsia and acid indigestion, such as antacids. These are described in more detail in the article on upper GI tract problems.

Distension is the swelling up or ballooning of sections of the GI tract, usually due to trapped gas. It can be extremely painful. If the gas consists only of air swallowed with the food then it usually has no particular odour. If there is some blockage of the GI tract, however, such as pyloric stenosis (blockage of the valve between the stomach and intestines), then foul smells may be produced by bacterial fermentation of the food in the tract.

Certain foods, such as beans and cabbage, are also known to cause foul smelling flatus or gases in normal individuals. This can be a particular problem for people with irritable bowel syndrome. Avoiding these foods is usually helpful.



The terms bilious or liverish are used to describe a range of GI tract problems, including nausea and vomiting, but generally mean a heavy or sluggish feeling. The remedies available include antacids and health salts or 'liver salts' containing carbonates.

Summary of management of lower GI tract problems




identifying and treating the cause of the pain

paracetamol or codeine - not aspirin or ibuprofen as these can irritate the GI tract lining


improving lifestyle and diet

stopping smoking


bismuth salts

dill, cardamom

Nausea and vomiting

prescription medicines

bismuth salts

antihistamines and anticholinergics for travel sickness


loperamide, low doses of morphine with kaolin to slow down gut movements

salt and glucose for severe diarrhoea, especially in babies and children


high fibre diet plus plenty of fluids


regular exercise


health salts



herbal remedies

dietary changes (avoiding gas-producing foods)



health salts (including 'liver salts')