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Greater Knox Pharmacy

43 Boronia Road, Boronia VIC 3155
Tel: 03-9739-8951
Email: admin@greaterknoxpharmacy.com.au
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Constipation

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1. Overview

The colon’s main job is to absorb water from residual food as it’s passing through the digestive system.

The colon’s muscles eventually propel the waste out through the rectum to be eliminated. If stool remains in the colon too long, it can become hard and difficult to pass.

Although the normal frequency of bowel movements varies from person to person, about 95% of healthy adults have a pattern that ranges from three times a day to three times a week.

In constipation, bowel movements either occur less often than expected or the stool is hard, dry and difficult to pass.

Constipation may be considered chronic if you've experienced two or more of these symptoms for the last three months.

2. Symptoms

Signs and symptoms of chronic constipation include:

  • Passing fewer than three stools a week
  • Having lumpy, hard or dry stools that may be painful to pass
  • Straining to have bowel movements
  • Having to sit on the toilet for much longer than usual
  • Bloated abdomen or abdominal cramps
  • Feeling as though there's a blockage in your rectum that prevents bowel movements
  • Feeling as though you can't completely empty the stool from your rectum
  • Needing help to empty your rectum, such as using your hands to press on your abdomen and using a finger to remove stool from your rectum

⚠ 2.1 RED FLAGS 🚩🚩🚩

See your doctor if you have any of the following:

  • Blood, dark or tarry stool
  • Weight loss
  • Severe abdominal pain
  • Age > 50 with new onset or worsening symptoms
  • Iron deficiency anaemia
  • Fever
  • Anorexia, Vomiting
  • Constipation alternating with diarrhoea
  • Family history of Inflammatory Bowel Disease
  • Family history of Colon Cancer
  • Symptoms persisting after 1 week of laxative use or 2 weeks of dietary modification

3. Diagnosis

Diagnosis is generally made based on symptoms and duration. The doctor may also do a physical examination and order some tests to be able determine the cause of constipation. These tests may include:

  • Blood tests. Your doctor will look for a systemic condition such as low thyroid (hypothyroidism) or high calcium levels.
  • An X-ray. An X-ray can help your doctor determine whether our intestines are blocked and whether there is stool present throughout the colon.
  • Colonoscopy. Examination of the rectum and entire colon.
  • Anorectal manometry. An anorectal manometry is a test used to evaluate anal sphincter muscle function.
  • Sigmoidoscopy. Examination of the rectum and lower, or sigmoid, colon.

4. Causes

4.1 Lifestyle and Diet

  • Inadequate dietary fibre
  • Dehydration (made worse with caffeine and alcohol)
  • Some foods such as:
    • Milk, cheese and other dairy products
    • Unripe bananas
    • White rice, white bread, pastries and processed grains in general
    • Cruciferous veggies: Cauliflower, Kale, Cabbage, etc
    • Fried food (chips, chicken, fish, donuts, etc)
    • Fast food and frozen meals
    • Persimmon
    • Animal products (to an extent, such as red meat, egg, dairy, etc)
    • Carbonated beverages
    • Chocolate (especially dark)
    • Legumes and high fibre food without sufficient water consumption
  • Inappropriate bowel habits (eg ignoring the urge to go means that more water will be extracted from the stools, making them difficult to pass. Regularly ignoring this urge may make the body less sensitive to normal signals to go to the toilet.)
  • Inadequate physical activity or regular exercise (e.g. living a sedentary lifestyle or being restricted in movement due to a disability are common causes of constipation.)
  • Change in environment (eg holiday, entry into a residential aged care facility, travel, shift work, etc)

4.2 Pregnancy

The action of hormones, reduced activity and the pressure of the growing uterus against the intestines mean that constipation is common during pregnancy.

4.3 Advancing Age

Constipation is more common in the elderly. This is due to a number of factors, including reduced intestinal muscle contractions and reliance on regular medications.

4.4 Medication

  • Opioids
  • Drugs with anticholinergic effects (some Antihistamines, Hyoscine, Oxybutynin, Benzhexol, Tricyclic Antidepressants, Clozapine, Olanzapine, Risperidone, Quetiapine)
  • 5-HT3–receptor antagonists (eg Ondansetron)
  • Aluminium and calcium containing antacids
  • Calcium supplements
  • Iron supplements
  • Calcium Channel Blockers especially Verapamil
  • Pregabalin
  • Dopamine agonists (Pramipaxole, Bromocriptine)
  • Vinca alkaloids

4.5 Disease

Painful Anorectal Disorders

  • Haemorrhoids
  • Anal fissure
  • Hernia
  • Abdominal or gynaecological surgery

Irritable Bowel Syndrome

Chronic Laxative Overuse

Influence Of Hormonal Changes

  • Diabetes
  • Overactive parathyroid gland (hyperparathyroidism)
  • Underactive thyroid (hypothyroidism)
  • Hypopituitarism

Blockages In The Colon Or Rectum

  • Haemorrhoids
  • Rectal prolapse
  • Bowel obstruction
  • Bowel stricture
  • Colon cancer
  • Other abdominal cancer that presses on the colon
  • Rectal cancer
  • Rectum bulge through the back wall of the vagina (rectocele)

Loss Of Muscle Power Caused By Other Medical Conditions

  • Problems with the nerves around the colon and rectum
  • Chronic obstructive pulmonary disease (COPD)
  • Multiple sclerosis
  • Parkinson's disease
  • Spinal cord injury
  • Stroke
  • Anismus (The inability to relax the pelvic muscles to allow for a bowel movement)
  • Dyssynergia (Pelvic muscles that don't coordinate relaxation and contraction correctly)
  • Weakened pelvic muscles

Mental

  • Anxiety
  • Depression
  • Grief

5. Complications

  • Faecal impaction – the lower bowel and rectum become so packed with faeces that the muscles of the bowels can’t push any of it out.
  • Faecal incontinence – an overfull bowel can result in involuntary ‘dribbling’ of diarrhoea.
  • Haemorrhoids – constant straining to open the bowel can damage the blood vessels of the rectum.
  • Anal fissure – a tear in the lining of the anus (anal mucosa).
  • Rectal prolapse – the constant straining pushes a section of rectal lining out of the anus.
  • Urinary incontinence – the constant straining weakens pelvic floor muscles. This makes the involuntary passing of urine more likely, especially when coughing, laughing or sneezing.

6. Prevention and Treatment

There isn’t enough data to compare effectiveness and tolerability between laxatives. Drug choice may be based on symptoms, required onset of action, hardness of stool, personal preference, adverse effects, effectiveness of previous treatments and cost.

Some simple measures that can alleviate and prevent constipation include:

  • Drink enough water. Usually 6-8 glasses daily. Especially important when increasing the fibre content in the diet.
  • Increase the fibre content in your diet. Aim for 18-30g per day. Good sources of fibre include wholegrain cereals, fruits, vegetables and legumes
  • Increase exercise and physical activity most days of the week. Aim for 30 minutes daily.
  • Don’t ignore the urge to have a bowel movement, especially after meals.
  • Limit causes of dehydration such as alcohol, coffee, tea, etc.
  • Identify and treat any underlying cause or disease.

A stepped approach can also be used. Start with a bulk forming laxative (with adequate fluid intake), then add or switch to an osmotic laxative if inadequate (especially if stools remain hard). Stimulant laxatives are used if colon motility is poor (e.g. from opioids), otherwise they are reserved as a second-line option (if stools are soft but difficult to pass). Adjust dose and choice of laxatives according to response.

6.1 Pregnancy

Dietary and lifestyle changes are preferred. If inadequate, bulk forming laxatives may be given to supplement fibre intake. Docusate, lactulose and sorbitol are safe to use; consider if stools remain hard. If these are ineffective, use an occasional dose of macrogol laxative; avoid stimulant laxatives.

6.2 Opioid-induced constipation

Start laxatives when beginning opioid analgesia. If a patient is already taking laxatives, monitor and adjust or add laxatives if needed. Agents of choice include either a stimulant laxative combined with a stool softener or an osmotic laxative

Do not use bulk-forming laxatives and be cautious if increasing dietary fibre (increasing bulk may worsen constipation, particularly if the patient is dehydrated or immobile).

For resistant cases or established opioid-induced constipation use:

6.3 Fibre and Bulk Forming Laxatives

Constipation can occur from a high-fibre diet if insufficient water is consumed.

There are two broad types of fibre; soluble and insoluble. Soluble fibre helps to soften the faeces. Good sources of soluble fibre include legumes, fruits and vegetables. Insoluble fibre adds bulk to the faeces, helping it to move more quickly through the bowel. Good sources of insoluble fibre are in wheat bran, wholegrain breads and cereals.

Aim for 18-30g per day, and make sure to get enough water (6-8 glasses per day for most people).

Other points to consider:

  • Should not be taken immediately before going to bed
  • Full effect may take several days
  • Gradual increase may reduce gastrointestinal side effects
  • Some products contain frangula (buckthorn) bark, which is one of the stimulant laxatives

Brand Ingredients Form Onset of action Pregnancy Breastfeeding
Metamucil Psyllium capsules, powder 2-3 days Safe Safe
Fybogel Ispaghula granules 2-3 days Safe Safe
Normacol Plus Frangula bark, Sterculia granules 2-3 days Not recommended May be used
Normafibe Streculia granules 2-3 days Safe Safe

6.4 Osmotic Laxatives

Glycerol can be used for rapid relief of constipation when stool is present in the lower rectum.

Lactulose and sorbitol need to be taken regularly. They are not suitable for acute relief of constipation as they can take several days to have an effect.

Macrogol laxatives may contain electrolytes to minimise electrolyte and water loss. They may take several days to have an effect. Use with caution in people with heart Failure or Renal Impairment.

Saline laxatives contain poorly absorbed ions such as magnesium, phosphate, sulfate and citrate. They have a fast onset of action and are suitable for occasional use when rapid bowel evacuation is required. There is a risk of electrolyte disturbance, particularly in the elderly, children and patients with renal impairment or cardiovascular disease. Phosphate-containing laxatives should not be used in the elderly.

Brand Ingredients Form Onset of action Pregnancy Breastfeeding
Actilax, Dulose, Duphalac Lactulose Oral Liquid 1-3 days Safe Safe
Movicol, Osmolax Macrogol 3350 Powder 1-3 days Limited data Safe
Epsom Salts Magnesium Sulfate Powder 1-3 days Limited data Safe
Microlax Sorbitol, Sodium Citrate, Sodium Lauryl Sulfoacetate Enema 2-30 minutes Safe Safe
Fleet Sodium Phosphate Enema 2-5 minutes Limited data Safe
Glycerol Glycerol Suppository 5-30 minutes Safe Safe

6.5 Stimulant Laxatives

Stimulant laxatives tend to be reserved for opioid-induced constipation (below) or severe constipation unresponsive to bulk-forming laxatives or osmotic laxatives. They are usually given at night to help produce a bowel action the following morning. Short-term use is preferred, although they may be used long term in spinal damage, chronic neuromuscular disease and in people taking opioids.

Brand Ingredients Form Onset of action Pregnancy Breastfeeding
Dulcolax, Bisalax, Lax-Tab Bisacodyl Tablets, suppositories, enema 6-12 hours (oral),
15-60 minutes (supp),
5-15 minutes (enema)
Avoid May be used. Monitor infant
Senokot, Laxettes Senna Tablet 6-12 hours Avoid May be used. Monitor infant
Coloxyl & Senna Docusate + Senna Tablet 6-12 hours Avoid May be used. Monitor infant
Dulcolax SP Drops Sodium Picosulfate Drops 6-12 hours Avoid May be used. Monitor infant

6.6 Stool Softeners and Lubricants

May be used to treat constipation (usually combined with a stimulant or osmotic laxative), prevent straining after rectal surgery and in patients with anal fissures or haemorrhoids.

Brand Ingredients Form Onset of action Pregnancy Breastfeeding
Coloxyl Docusate Tablets 1-3 days Safe Safe
Parachoc Liquid Paraffin Liquid 2-3 days Limited data Safe
Coloxyl Drops Poloxamer Liquid 2-3 days Unknown Unknown

7. References

  1. Australian Medical Handbook, July 2020
  2. Mayo Clinic
  3. Harvard Medical School
  4. Healthline
  5. Better Health Channel
  6. MSD Manual
  7. Royal Children's Hospital