Opioids and Constipation

Cite this article as:
Ben Lawton. Opioids and Constipation, Don't Forget the Bubbles, 2016. Available at:

Opioids and constipation


The bottom line

-Opioids are an illogical choice for treating pain associated with constipation

-Pain needs to be treated promptly and effectively

-Abdominal pain requiring opioids should raise suspicion of a surgical diagnosis


Why are we talking about opioids and constipation?

This post arose from a twitter conversation that began with the question “Is it ever OK to use opioids for treating the pain associated with constipation?” some people said “No, never!

Why shouldn’t we use opioids to treat constipation?

A  universal side effect of opioid medication is constipation. In the case of codeine this comes without a useful analgesic effect in a significant proportion of the population so that one is definitely best avoided. Essentially in using opioid medication to treat constipation associated pain you are exacerbating the underlying problem.

Why should we use opioids to treat constipation?

Gone are the days when it was considered OK to leave a patient in pain so as not to reduce the physical signs that would be used to diagnose surgical disease. Pain management is one of the things that we can and should do rapidly and effectively for any patient of any age coming to see us in the ED.   Opioids are generally very effective analgesics and most staff in our departments will be comfortable with their use.

What are the alternatives?

Our usual go to medications, paracetamol and ibuprofen, are usually the first thing to try but simple interventions like hot packs are often helpful and underutilized.

How sure are we about the diagnosis?

Constipation can indeed be painful, sometimes dramatically so. It is also extremely common.   We often work on the principle that if you have a single, strong diagnosis that explains a patient’s symptoms then it’s OK to stop investigating.   There are of course exceptions to this rule. It’s an old joke that the hardest type of fracture to pick up is the second fracture and a subset of under-reporting errors in radiology has been assessed and published as being due to “search-satisfaction” or stopping looking because you have found one abnormality (1). This is relevant as although constipation can indeed cause pretty bad abdominal pain it is common enough that kids can be constipated and have appendicitis!!

What about enemas?

There are a few opinions about this but I think the role of enemas in managing constipation is extremely limited. Lots of constipated kids (indeed lots of kids in general) don’t like people putting things up their bottoms. Not only is it awkward even for fairly young children it is also often painful. Many constipated kids are in a vicious cycle of holding on because it hurts when they poo, which leads them to build up bigger and firmer stools, which makes it hurt even more when they do go to pass that stool. This not infrequently leads to anal fissures. These are exquisitely tender and do not respond well to being poked with plastic tubes. If constipation is an ongoing problem for a child then further visits to doctors or other health care professionals are likely and these become more difficult for the practitioner and, more importantly, distressing for the child if they come with a fear or even an expectation of someone hurting them.

Are enemas safe?

Microlax™ products are advertised for use in babies (they even have tips for use in infants on their website). Sodium phosphate or “fleet” enemas may be appropriate in older children but in smaller children and especially with repeat dosing the phosphate load carries a very real risk of causing hypocalcaemia with hypocalcaemic tetany having been reported after just 2 doses (2). It is hard to imagine many circumstances in which a phosphate enema is truly the best option for any child under 5. Certainly repeat dosing should be approached with extreme caution in any paediatric patient.

When should I call a surgeon?

The diagnosis of constipation really requires the consideration and exclusion of more sinister causes of abdominal pain. The usual red flags (bilious vomiting, significant abdominal distension, well localized pain, etc) should be actively sought and not overlooked should their presence be found. In this author’s opinion the repeated need for opiates to treat abdominal pain in children should be considered a red flag in itself and in most practice environments should prompt the involvement of the surgical team in the child’s care.


For more on constipation take a look at our week long series:- 

The basics

Understanding constipation


Evidence on tough topics

Advice and information for parents



  1. Berbaum KS et al satisfaction of search in diagnostic radiology. Invest radiol 1990 feb;25(2):133-40
  2. Craig JC et al. phosphate enema poisoning in children. Med J aust 1994 Mar 21;160(6):347-51

Constipation week – Day 4: Evidence on Tough Topics

Cite this article as:
Angela Clarke. Constipation week – Day 4: Evidence on Tough Topics, Don't Forget the Bubbles, 2014. Available at:

Bottom line: (pun definitely intended!)

  • A PR examination should only be undertaken by a doctor competent to interpret features of anatomical abnormalities or Hirschsprung’s disease e.g. paediatric surgeons
  • TFTs and coeliac screen should only be ordered by specialists in patients with intractable constipation
  • Abdominal xrays and abdominal ultrasounds are not recommended to aid diagnosis of constipation
  • Dietary interventions alone are not recommended but should be used in conjunction with a laxative
  • According to evidence, PEG 3350 (Movicol) should be the oral laxative of choice
  • Maintenance regimes should be continued for several weeks to months
  • Routine use of enemas is not recommended

See our other Constipation Week posts

Do I order TFTs and coeliac screen?

Thyroid function testing and coeliac screening should only be ordered by a specialist service as part of the investigation of intractable constipation when atypical presentations of these diseases are considered. There are no published studies stating the prevalence of coeliac disease and hypothyroidism in children with idiopathic constipation (Reuchlin-Vroklage et al, 2005).

Should I get an abdominal x-ray to confirm my diagnosis?

Evidence shows that abdominal x-rays play little role in confirming or refuting the diagnosis of constipation as there is poor diagnostic accuracy and reproducibility (Reuchlin-Vroklage et al, 2005). It is important to remember that the average radiation dose of an abdominal x-ray is 0.7mSv, that’s 7 times higher than a chest x-ray. That is relatively high compared to the background yearly exposure of approximately 3mSv (Mettler et al, 2008).

What about an abdominal ultrasound?

Abdominal ultrasounds have shown that children with idiopathic constipation have a larger rectal diameter than those without constipation. However, they don’t give any extra information than what is obtained through thorough history taking and examination and are therefore not routinely recommended.

Which laxative do I choose?

There are a series of case series and randomized control trials that show treatment with PEG 3350 was effective in causing disimpaction of children with constipation.  The studies show that higher doses are more effective than smaller doses and that PEG 3350 is more effective than stool softeners and enemas (Youssef et al, Tolia et al, Guest et al ). There is currently no evidence of the effectiveness of stimulant laxatives in treating disimpaction.

The NICE ‘Constipation in children and young people’ guidelines suggest the following management for children over 1 year of age:

  1. Rule out ‘Red flags’.
  2. Assess for impaction – i.e. overflow soiling and/or faecal mass palpable abdominally. Start maintenance therapy for those not faecally impacted, treat for disimpaction if faecally impacted.
  3. Treat for disimpaction or commence maintenance therapy:
    • 1st line – Macrogol PEG 3350  – escalating dose regime for disimpaction or adjusted according to response in maintenance regime.
    • 2nd line – (2 weeks later) Add a stimulant laxative (e.g. sodium picosulfate,  bisacodyl, senna,)
    • 3rd line – Substitute a stimulant laxative singly or in combination with an osmotic laxative (lactulose) if Macrogol PEG 3350 not tolerated.
    • 4th line – Enema (stimulant laxative: Microlax or Bisacodyl)
    • 5th line – Manual evacuation under anaesthetic.
  4. Continue maintenance regime for several weeks to months.
  5. Medications not to be stopped abruptly but to be weaned over a period of months.

Dosage guides are provided in the guideline – https://guidance.nice.org.uk/CG99.



Reuchlin-Vroklage LM, et al. Diagnostic value of abdominal radiography in constipated children: a systematic review. Archives of Pediatrics and Adolescent Medicine. 2005;159(7):671-8.

Mettler FA, et al.  Effective Doses in radiology and Diagnostic Nuclear Medicine: A Catalog. Radiology. 2008 Jul ;248(1):254-63.

Youssef NN, et al. Dose response of PEG 3350 for the treatment of childhood fecal impaction. Journal of Pediatrics. 2002;141(3):410-4.

Tolia V, et al. A prospective randomized study with mineral oil and oral lavage solution for treatment of faecal impaction in children.  Alimentary Pharmacology and Therapeutics. 1993;7(5):523-9.

Guest JF, et al. Clinical and economic impact of using macrogol 3350 plus electrolytes in an outpatient setting compared to enemas and suppositories and manual evacuation to treat paediatric faecal impaction based on actual clinical practice in England and Wales. Current Medical Research and Opinion. 2007;23(9):2213-25.

Candy DC, Edwards D, Geraint M. Treatment of faecal impaction with polyethelene glycol plus electrolytes (PGE + E) followed by a double-blind comparison of PEG + E versus lactulose as maintenance therapy. Journal of Pediatric Gastroenterology and Nutrition. 2006;43(1):65-70.

Pashankar DS and Bishop WP. Efficacy and optimal dose of daily polyethylene glycol 3350 for treatment of constipation and encopresis in children. Journal of Pediatrics. 2001;139(3):428-32.