Know Your IBS Sub-Type

You’ve probably worked out by now that IBS isn’t a ‘one size fits all’ problem. The severity and the type of symptoms vary hugely from one person to the next. You might be struggling with horrible bloating and constipation, wishing you could go to the toilet. On the other hand, your friend might be wishing she was in your position, as her IBS leaves her running for the nearest toilet far too often. However, you’ve both got the same thing - IBS.

When it comes to trying to take control of your IBS, the first step is getting a proper diagnosis (I wrote about this last week). Once you’re totally sure that you’ve got IBS, the next step is to work out your IBS sub-type.

You can use the Rome diagnostic criteria to do this, and this criteria outlines 4 types of IBS.



The Rome criteria say that you can be diagnosed with IBS if you have recurrent tummy pain at least 1 day a week in the last 3 months, associated with going to the toilet, a change in how often you poo or a change in your poo consistency.

Within this, it sets out criteria for 4 sub-types, which use the Bristol stool chart (see below).


1. IBS-C

Official diagnostic criteria: ‘>25% bowel movements with Bristol stool form types 1 or 2 AND <25% bowel movements with Bristol stool form types 6 or 7’

What this means: IBS with constipation. This means you have hard and lumpy poo more than 25% of the time. You also get bloating and tummy pain and find it difficult to go to the toilet, which causes straining. You normally don’t go to the toilet more than 3 times a week.


2. IBS-D

Official diagnostic criteria: ‘>25% bowel movements with Bristol stool form types 6 or 7 AND <25% bowel movements with Bristol stool form types 1 or 2’

What this means: IBS with diarrhea. This means you have watery or loose poo more than 25% of the time and hard poo less than 25% of the time. You can also get tummy pain, gas and sudden urges to run to the toilet.


3. IBS-M

Official diagnostic criteria: ‘>25% bowel movements with Bristol stool form types 1 or 2 AND >25% bowel movements with Bristol stool form types 6 or 7’

What this means: a bit of both. You alternate between constipation and diarrhea, so you get both hard and soft stools more than 25% of the time. You can also suffer with tummy pain, gas, bloating, straining or sudden urges to run to the toilet.


4. IBS-U

Official diagnostic criteria: ‘patients who meet diagnostic criteria for IBS but whose bowel habits cannot be accurately categorised into one of the 3 groups above’

What this means: this just means that you do have IBS as you’ve met the Rome criteria for diagnosis. However, there hasn’t really been much of a change in your poo, so you don’t fit into any of the above categories.



The Bristol Stool Chart

  • Types 1–2 are hard lumpy stools that are hard to pass. If you mainly have this type of stool, it suggests you might have IBS-C.

  • Types 3–4 are ideal stools – they are easier to pass, and are what is considered a healthy poo.

  • Types 5–7 indicate diarrhoea and urgency. If you experience these types of stools most of the time, it would make sense that you have IBS-D.



It’s quite evenly spread, actually. About 1/3 of people have IBS-C, 1/3 IBS-D and then 1/3 to 1/2 have IBS/M…and the rest have IBS-U. So, there doesn’t seem to be a more common sub-type. Whichever group you’re in, you’re very much not alone.



You might, at this point, be wondering why it really matters which type of IBS you have. You’d rather someone just told you what to do to fix it. However, knowing you’re sub-type is so helpful, because each sub-type has different triggers. This means there are different tools and tweaks that can help you to manage each sub-type.

Yes, some tools will work for all types of IBS, e.g. eating regular meals. However, some will work well for some sub-types but actually make symptoms worse for other sub-types. For example, if you have IBS-C, a recommendation to add more (of the right types) fibre to your diet may help reduce your constipation. On the other hand, if you have IBS-D, this same recommendation might make your symptoms even worse!

Therefore, it’s incredibly helpful to know your sub-type so that you can implement specific tools and recommendations that will suit you and actually help your symptoms, rather than make them worse.




  1. It’ll be totally obvious - from reading the above descriptions which one you fit into.

  2. Keep a record of your poos - for a week, keep a record of when you go to the toilet, and what type your poo is (using the Bristol stool chart). Pop in your details below and I’ll send you my ready made food + feelings diary, which has a space to record your poo too. At the end of the week, review your diary and work out which of the 4 sub-types you fall under.


  • There are 4 different sub-types of IBS, which are classified using the Bristol Stool chart

  • Work out which one you are - IBS-C, IBS-D, IBS-M or IBS-U

  • Neither of these sub-types is much more common than the other - there’s an even spread

  • It’s incredibly useful to know your sub-type, as you can then find specific tools to help ease your symptoms, not make them worse!

  • If you don’t already know you’re sub-type, keep a poo diary for a week and work it out.

Which sub-type are you? Let me know in the comments below.

Thanks so much for taking the time to read this and I hope it’s helped you on your journey towards more control of your gut,

Sophie x

Sophie BibbsComment