Causes of a Colitis Flare-up

Colitis Flare

For those new to colitis it might seem a bit strange that this website has a page about the causes of Colitis and a page about what causes Colitis to flare-up. However, they are two different things - this page is about flare-ups, not about the reasons why Ulcerative Colitis starts in the first place.

What is a Colitis flare?

A Colitis flare (often called a flare-up) occurs when the sufferer experiences any symptoms caused by Colitis. Technically, the only time a UCer is not in a flare is when they're in remission, which means there are no symptoms. However, some Ulcerative Colitis sufferers can have periods where there are very few symptoms and they'll often refer to it as being out of a flare-up.

Periods where Colitis is flaring can also be referred to as periods where Colitis is 'active'.

Example: Diary of a Colitis flare-up

When am I having a flare-up?

I often see the question 'how do I know I'm having a flare-up' posted on various forums. It's a good question because there are no definitive markers that a UCer can look at to get the answer. In fact, some Colitis sufferers can be virtually symptom free but still experience slight problems e.g. some mucus. This means, technically they're experiencing a 'mild' flare-up.

Flare-ups are often viewed in relative terms. For example, a UCer that has had a tough time but eventually gets to a stage where they're able to have a normal life, albeit with minor symptoms, will often consider themselves out of the flare-up (and who can blame them?) - I'd say this is probably the most commonly held viewpoint by UCers.

There are a lot of semantics used when this topic is being discussed, but personally I don't question a UCer's version of a flare-up or remission because Colitis is a very individual disease. I've seen broad statements used by UCers who view what they've been told as correct and take a different opinion as an insult. However, it's ridiculous to imagine what we've learnt or been told by a few applies to everyone suffering from Colitis!

Watch out there's a flare-up about!

Often a flare-up can creep up on you when you're least expecting it. Maybe after a few good months, where the memories of the symptoms slowly fade into the past and you let your guard down. It has happened to me more than once!

I've realised after many years that it's wise to stay alert to this and pay attention to any slight changes. Hopefully, most of the time feelings that are out of the ordinary will pass, but for the one time it continues, as UCers, we need to get on top of it as soon as possible. The trouble is that there are many different Colitis symptoms, so a flare could well begin with a feeling not experienced before.

As an example: I started getting itchy areas on my body just before the start of a recent flare-up, something that I'd never experienced, so I assumed it was due to something else. I'd been using a new shower soap around that time and was convinced something in it was causing the itchyness.

The result of not realising that my itchy skin was an early sign of a flare (the itchy skin got worse with the flare and finally went when the flare did) was that I descended into a fully blown flare-up. I only realised what was happening after I started experiencing a symptom I'd had before (urgency). Unfortunately, mesalazine tablets take around 3 weeks to take effect for me, but I was well into flaresville by then! Flaresville - a theme park for UCers (avoid the log flume!).

Mind you, I can't be too harsh on myself as it was a new symptom for me, but it has taught me a lesson about staying vigilant and treating any new feelings (and those already experienced) as a potential sign of a flare-up.

Flare-up causes

Please send your Flare-up causes

A quick reminder - this website is a work in progress so there will be symptoms some have experienced that aren't on the list. Please feel free to email me with your flare-up triggers so I can make the list more thorough. Thank you.


I found a very interesting survey on I Have UC, in which Colitis sufferers were asked what caused their flare-ups. There was a good cross section of answers but the main culprits (stress and diet) were the most popular by a long way.

It should also be mentioned that many of the UCers gave more than one answer, underlining the fact that there can be various triggers for each person.

The results of the survey to the question "what causes your flare-ups?":

  • Stress 38%
  • Diet 31%
  • Not Sure 12%
  • Lack of Sleep 3%
  • Menstrual Cycle 3%
  • Change of Seasons 2.5%
  • Antibiotics 2.5%
  • Viruses 2%
  • Non-Colitis Meds 2%
  • Pregnancy 1.2%
  • Forgetting Meds 1.2%
  • Over Exercise 0.8%
  • Exhaustion 0.8%
  • Over Eating 0.8%
  • Allergies 0.4%
  • Food Poisoning 0.4%
  • Heavy Lifting 0.4%
  • Stop Smoking 0.4%


There's a longstanding argument over the link between food and Colitis. Time and time again I see UCers say that their Doctor told them food can't cause a flare-up - I had a specialist say it to me. It's worth mentioning that sometimes what can cause 'Colitis' gets mixed up with what can cause a 'flare-up'.

For the record, I've also had a specialist tell me that "food can cause a flare-up for some", which is probably the most accurate response you will get on this argument. Bearing in mind that the definition of a flare is the 'occurrence of any symptom associated with Colits', the fact is that for some UCers, certain types of food can cause a flare-up.

I've had first hand experience of this on two occasions when eating insoluble fibre. Once after eating wholemeal bread for a few weeks and another time when I ate Weetabix for about a week. They both caused blood (symptoms of a flare) and I went on to experience mucus and urgency along with the bleeding as a result of eating the bread.

So, there's a long list of foods that has caused symptoms for colitis sufferers, which underlines just how individual the disease is. As with diet, it's not really that relevant from one UCer to the next, but sometimes it can help us identify a food that may cause problems if we spot it in someone else's list but hadn't thought of it for ourselves.

The list below of made up of responses from different colitis sufferers, not one person!!

  • Beef
  • Bran cereals
  • Chocolate bars
  • Corn
  • Dairy
  • Fruit skin
  • Hot liquids
  • Insoluble fibre
  • Ketchup
  • Onions
  • Processed food
  • Raw Tomatoes
  • Spiced food
  • Seeds
  • Tortilla Chips
  • Vegetable skin
  • Wholemeal bread


Stress always gets mentioned a lot when UCers discuss Colitis flare-ups. It also appears in the list of possible Colitis causes.

Background stress over a long period of time and extreme short term physical and/or mental stress both lower the immune system, leaving UCers susceptible to different ways for Colitis symptoms to develop, so it makes sense that it appears in a list of triggers behind flare-ups.

It's interesting to note that whether caused by a stressful situation, anxiety, an accident, over exercise etc. etc., the symptoms in the colon are the same e.g. it doesn't differentiate between types of stress.


Lack of sleep is a fairly common occurrence with those suffering from IBD, and an increase in studies on the affects of sleep deprivation shows that a good night's sleep is important in relation to inflammation.

A study on mice showed that sleep deprivation showed increased inflammation in the colon and slower mucosal recovery.

The interesting thing is that for me, it only takes a couple of nights of poor sleep to start showing colitis symptoms. I have experienced lack of sleep due to stress, and it led to pains in the sigmoid colon as well as blood in the stool.

Cold/Flu virus

Here's a flare-up trigger that is fairly well known. The weakening of the immune system during a virus leaves UCers open to triggers that could start a flare up.

My most recent flare-up really took hold when I had a bad cold although it has to be said that I was having a few minor Colitis symptoms before the cold kicked in.

Menstrual Cycle

Many Ucers believe that their menstrual cycle has an effect on their colitis, there are articles that support this view with the belief that the cycle, or more specifically hormones, can exacerbate Ulcerative Colitis symptoms.

The question whether menstruation effects Colitis gets asked frequently on forums. One of the main symptoms for those with UC seems to be the increase in cramps and diahrrea on the lead up to and/or during their menstrual cycle.


I've seen winter and cold weather mentioned a few times in discussions about Colitis symptoms and flare-ups. After reading lots of threads and posts, it appears to me that the seasons most talked about are Autumn and Winter - some UCer's flare-ups start at the same time each year, almost to the week!

Articles on the subject seem to say that cold weather isn't the reason behind a weaker immune system, but the fact that we stay indoors and become more sedentary which means we aren't boosting our immune system with exercise. It's also pointed out that staying indoors during colder months means we are more likely to be in close proximity of other people, which in turn, increases the chances of picking up a virus leading to a weakening of the immune system.

Unfortunately the problem is that there are so many possible influences, it's very difficult to determine what it is about winter or a change of season that could be a factor. I've seen many suggest that the lack of sunlight and lack of vitamin D is part of the problem, indeed quite a few UCers report that they improved or had no symptoms at all when they were on holiday in a sunny climate - of course, one imagines the de-stressing factor of being on holiday would also be relevant.

So, I wouldn't write anything off because there are so many variables. Something that happens during a change of season could well be the trigger behind a Colitis flare. I guess a detailed diary of what the UCer was doing each year is needed to find a more precise conlcusion.

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