If your child is constipated, or has a fear of pooing due to past constipation, macrogol laxatives can help. I hear from many parents who worry about using them, especially in the long term. So how safe are they?
What are macrogol laxatives?
Brand names in the UK include Movicol, Cosmocol and Laxido and they belong to a group of laxatives called osmotic, or macrogol laxatives (1). The active ingredient is called macrogol 3350, also known as polyethylene glycol (PEG), which is a synthetic water-soluble polymer. They come in sachets, in the form of powder, which are mixed with water.
How do macrogol laxatives work?
They work by increasing the amount of water passing along the bowel. When the powder is mixed with the water, the powder binds with the water and makes the water molecules bigger. When you drink the liquid, the water cannot pass through the bowel wall, because the molecules are too big. So instead, the water molecules pass along the bowel and out the other end. Through this process, they help soften the poo as well as keep it moving along. In effect, they ‘flush out’ the poo!
Can you have too much?
You might think that giving your child 8 or 12 sachets a day for a week or two, to help get rid of accumulated poo, sounds like a heck of a lot of medication. But, what you are really doing is flushing the bowel with extra water, and that’s all. It’s difficult, if not impossible to overdose on macrogol laxatives as long as you stick within the recommended range.
Do macrogols get into the blood stream?
The answer is yes, but only minimally. Studies have shown that when taken by mouth, PEG-3350 is minimally absorbed, rapidly excreted and primarily eliminated via poo (2). PEG is not known to be metabolised in humans and there are no known pharmacological actions or confirmed toxicity resulting from the limited absorption.
are there alternatives?
Macrogol laxatives are the first line recommended treatment for constipation in children. They have been shown to be more effective than Lactulose (the sweet, sticky syrup laxative), stimulant laxatives (Senna, dulcolax, pico sulphate), Milk of Magnesia (white liquid, sometimes tastes milky) and probiotics (6,7).
why do they have to be prescribed?
In the UK, macrogol laxatives are only available to children on prescription. This is because all children with suspected constipation need to be seen by a medical practitioner to rule out any other potential medical problems. Some GPs will prescribe it over the phone if your child has already been seen.
so, Is it safe?
The short answer is yes. Macrogol laxatives have been around a long time, so we have a lot of safety data on them. They are very well tolerated. A study in 2003 looked specifically at the clinical and biochemical safety profile of long-term polyethylene glycol 3350 (PEG) therapy in children with chronic constipation. It measured the blood levels and overall health of 83 children over 3 months and found that Long-term PEG therapy is safe and is well accepted by children with chronic constipation with and without encopresis (3). Similar results have been reported elsewhere (4), including in infants (5). In the UK, they are recommended by the National Institute of Clinical Excellence (NICE), whose job it is to independently review the safety and efficacy of medicines before they are recommended for use.
What are the side effects?
Common side effects, reported in users include flatulence; gastrointestinal discomfort; nausea; vomiting, sore bottom. These are usually mild and pass quickly. If your child vomits repeatedly, ask your GP, or if you have any concerns about their health whilst taking macrogol laxatives, seek medical advice.
By far the most important side effect to avoid is a sore anus, which is common. You can help avoid this by using Sudocreme or another suitable barrier cream on the skin.
If your child has any of the following symptoms whilst taking macrogol laxatives, get in touch with your healthcare profession as soon as possible:
- severe diarrhoea or vomiting
- feeling more tired than usual
- shortness of breath
- swollen ankles, feet or legs (oedema)
- muscle weakness
- irregular heartbeat
Although these symptoms are rare, they may be a sign that macrogol laxatives are not suitable for your child. Further advice can be found on the NHS website.
Where can I find out more?
Here is a video with 4 top tips for using Macrogol laxatives effectively and safely.
You can review more clinical evidence on macrogol laxatives here: https://www.nice.org.uk/guidance/cg99/evidence/evidence-update-pdf-245462365
(1)https://bnfc.nice.org.uk/drugs/macrogol-3350-with-anhydrous-sodium-sulfate-potassium-chloride-sodium-bicarbonate-and-sodium-chloride/
(2) PELHAM, R.W., NIX, L.C., CHAVIRA, R.E., CLEVELAND, M.V. and STETSON, P. (2008), Clinical trial: single- and multiple-dose pharmacokinetics of polyethylene glycol (PEG-3350) in healthy young and elderly subjects. Alimentary Pharmacology & Therapeutics, 28: 256-265.
(3) Pashankar DSLoening-Baucke VBishop WP. Safety of Polyethylene Glycol 3350 for the Treatment of Chronic Constipation in Children. Arch Pediatr Adolesc Med. 2003;157(7):661–664.
(4) Gremse DAHixon JCrutchfield A Comparison of polyethylene glycol 3350 and lactulose for treatment of chronic constipation in children. Clin Pediatr (Phila). 2002;41225- 229, McGraw T. Safety of polyethylene glycol 3350 solution in chronic constipation: randomized, placebo-controlled trial. Clin Exp Gastroenterol. 2016 Jul 15;9:173-80.
(5) Roy, D., Akriche, F., Amlani, B., & Shakir, S. A. W. (2021). Utilisation and safety of polyethylene glycol 3350 with electrolytes in children under 2 years. Journal of Pediatric Gastroenterology and Nutrition, 72(5), 683-689.
(6)Ratanamongkol P, Lertmaharit S, Jongpiputvanich S (2009) Polyethylene glycol 4000 without
electrolytes versus milk of magnesia for the treatment of functional constipation in infants and young children: a randomized controlled trial. Asian Biomedicine 3: 391–399
(6) Chmielewska A, Szajewska H (2010) Systematic review of randomised controlled trials: probiotics for functional constipation. World Journal of Gastroenterology 16: 69–75 and Coccorullo P, Strisciuglio C, Martinelli M et al. (2010) Lactobacillus reuteri (DSM 17938) in infants with functional chronic constipation: a double-blind, randomized, placebo-controlled study. The Journal of Pediatrics 157: 598-602
(7) https://www.nice.org.uk/guidance/cg99/evidence/evidence-update-pdf-245462365
Nurse Rebecca Mottram is an advocate for Baby Pottying and a potty training expert. She is the author of two books; The Baby Pottying Guide and Positively Potty, the host of the Go Potty Podcast and founder of the Little Bunny Bear shop. If you are trying to resolve a potty problem, you can explore Rebecca’s free resources, join her Facebook group or request a private consultation.