How to Tell If You're in a Crohn's Flare

Here is the uncomfortable answer that almost no article gives you: in Crohn's disease, how you feel is a weak guide to whether you are inflamed. In a study of 164 people with Crohn's who all had a colonoscopy, the standard symptom score showed essentially no relationship with what the endoscopist actually saw, with a correlation coefficient of 0.15 (Jones 2008). Some people felt awful with a calm bowel. Others felt fine with ulcers.

So "how do I tell if I am flaring" cannot be answered by matching yourself against a symptom list. What it can be answered by is a three-part process: knowing your own baseline well enough to see a genuine change, working through the look-alikes that produce identical symptoms without any new inflammation, and getting the one or two tests that settle it. This guide walks through all three, with the specific traps that catch people with Crohn's rather than with colitis.

The short answer: symptoms raise the question, tests answer it

If you want one sentence: a Crohn's flare means active inflammation, you cannot confirm inflammation by how you feel, and the fastest route to an answer is a written week of your own numbers plus a faecal calprotectin test arranged by your IBD team.

That is worth sitting with, because the whole internet tells you otherwise. Search results for this question serve up lists of symptoms: diarrhoea, cramping, fatigue, weight loss, low-grade fever. All of those can happen in a flare. None of them is specific to one, and none of them proves inflammation.

The evidence for that gap is unusually clean. Jones and colleagues enrolled 164 people with Crohn's who were all having a colonoscopy, and measured the Crohn's Disease Activity Index, the endoscopic score, blood CRP, interleukin-6, and faecal calprotectin and lactoferrin at the same time. There was no significant association between the symptom index and the endoscopic score, or between the symptom index and any of the biomarkers. The biomarkers, by contrast, were clearly higher in people with more severe endoscopic disease (Jones 2008). Symptoms and inflammation were measuring different things.

This is not an argument for ignoring your symptoms. Symptoms are the reason to investigate, they are what treatment is ultimately for, and nobody should be told their experience does not count. It is an argument against a specific and common mistake: deciding on your own that this is or is not a flare, and then acting on that decision by waiting it out, cutting out foods, or quietly adjusting treatment.

What "flare" actually means, and why the word causes arguments

A flare is a return of active inflammation in a bowel that was quieter before. A bad week is a stretch of symptoms that may or may not involve inflammation at all. Most of the confusion in Crohn's communities comes from those two things sharing one word.

When clinicians say "flare", they are usually thinking of the definitions used in trials and guidelines. The simplest bedside tool is the Harvey-Bradshaw Index, a five-item score covering general wellbeing, abdominal pain, the number of liquid stools, an abdominal mass and complications such as mouth ulcers, joint pain, eye inflammation, skin lesions, anal fissure, fistula or abscess (Harvey 1980). It correlates well with the longer Crohn's Disease Activity Index used in trials, with a Spearman correlation of 0.80 across almost 1,000 paired assessments, and a three-point change in the short index corresponds roughly to a 100-point change in the long one (Vermeire 2010).

But those are symptom scores, and we have already seen that symptom scores and inflammation part company. That is why international consensus now sets two layers of target. Symptom relief and normalisation of CRP and faecal calprotectin are short-term targets. Clinical remission and endoscopic healing are the long-term ones, with transmural healing in Crohn's assessed as a measure of how deep the remission goes (Turner 2021). In other words, the professional definition of "doing well" deliberately includes something you cannot feel.

Once you hold both meanings, a lot of contradictory advice makes sense at once. Someone telling you "that's just a bad day, not a flare" and someone telling you "any new symptom deserves a call" can both be right, because they are answering different questions.

Build your baseline before you need it

A flare is a change, so you can only detect one if you know what you are changing from. The single most useful thing you can do while you feel reasonably well is write down four numbers for two ordinary weeks.

Ask any group of people with Crohn's what tells them they are flaring and you get a list that barely overlaps. A thread in r/CrohnsDisease asking exactly that question drew dozens of different answers: sudden urgency that becomes predictable rather than occasional, mucus, blood, pain after solid food, hot flushes followed by chills, appetite loss, weight loss, and one person whose earliest tell was waking with a sore ear from lying on it (r/CrohnsDisease thread). Another thread produced night sweats, mouth ulcers, a bloodshot eye, insomnia, bloating and joint pain (r/CrohnsDisease thread). Several people said plainly that they always have loose stools, so stool form tells them nothing, and the count is what matters.

That variability is the point. There is no universal flare signature, so the only signature worth tracking is yours.

The four numbers worth having:

Add three context fields that repeatedly turn out to explain things: any missed treatment doses, any painkillers taken, and any recent antibiotics or illness in the household. Those three lines will save you an argument with yourself later.

If you keep the log on paper, a notebook by the bathroom door beats an app you have to unlock. If you prefer your phone, the point is the same: the record has to exist before the bad week, because reconstructing a month backwards is how people convince themselves of patterns that were not there. Our guide to keeping a food and symptom diary covers the mechanics, and most of it transfers directly.

Flare or stomach bug? The question the search results ignore

Timing and trajectory separate them better than the symptom list does. Infections usually start abruptly and improve over several days. A flare usually builds over one to three weeks and keeps building.

This is one of the most common real questions in Crohn's communities and one of the least served by published articles. A post titled "Flare or Stomach Flu, how do you know?" got a reply that captured the honest answer well: there is a lot of overlap, a clean scope does not stop a flare starting the next day because a test is a snapshot of one moment, and the practical move is to log symptoms and tell your GI team (r/CrohnsDisease thread). Another person described having proctitis-type bleeding throughout a three-month flare, catching gastroenteritis in the middle of it, having a week of violent diarrhoea with no blood, and then returning to exactly the flare pattern they had before. The bug and the flare were layered, not merged.

Some practical distinctions that hold up reasonably well:

• Onset. Food poisoning and viral gastroenteritis typically arrive over hours. A flare rarely does.
• Vomiting. Prominent vomiting early on points towards infection, although obstructive Crohn's can also cause it and that needs urgent assessment rather than watchful waiting.
• Company. If someone in your household or workplace has the same thing, that is a real clue.
• Direction of travel. After the first day or two, is each day better or worse than the last? Improvement over roughly five to seven days fits an infection. A steady climb does not.
• Blood. Visible blood is not a feature of most viral gastroenteritis, and new or increasing blood always deserves a prompt call to your team.

The complication worth knowing about is Clostridioides difficile. In a hospital series covering 1998 to 2004, rates of C. difficile infection roughly doubled among Crohn's admissions, from 9.5 to 22.3 per 1,000, and the adjusted odds of infection in Crohn's were about twice those of non-IBD admissions (Rodemann 2007). C. difficile can look exactly like a flare, can coexist with one, and is treated completely differently. That is why teams so often ask for a stool sample before changing anything. A frequent piece of advice in one Crohn's thread about distinguishing a flare from a failing biologic was the same: test for infection first, because being on immunosuppressive treatment makes infections more likely and they can either mimic or worsen a flare (r/CrohnsDisease thread).

The look-alikes that are not inflammation at all

If your calprotectin has come back normal and you still feel terrible, the answer is almost never "nothing is wrong". It is usually one of a short list of non-inflammatory causes that are genuinely more common in Crohn's.

IBS-type symptoms in remission. A meta-analysis of 27 studies and 3,169 people with IBD in remission found that 32.5% reported symptoms meeting criteria for irritable bowel syndrome. That figure was higher in Crohn's than in ulcerative colitis, at 36.6% against 28.7%, and it was still about a quarter when remission had been confirmed at colonoscopy or on biopsy (Fairbrass 2020). An earlier meta-analysis found the same direction, with pooled prevalence of 46% in Crohn's against 36% in ulcerative colitis (Halpin 2012). These symptoms are real, and they respond to different things than inflammation does.

Small intestinal bacterial overgrowth. Pooled across 11 studies of 1,175 people with IBD, 22.3% tested positive on breath testing, with odds around nine times higher than non-IBD controls. Two risk factors stand out for Crohn's specifically: fibrostenosing disease, with odds around seven times higher, and previous bowel surgery, particularly resection of the ileocaecal valve (Shah 2019). If you have had a resection and your bloating has become the dominant symptom, this belongs on the list of things to ask about.

Bile acid malabsorption. This is described as common but underestimated in inflammatory bowel disease, most clinically relevant in people with Crohn's ileitis and particularly after ileal resection, and frequently left out of diagnostic workups for cost and logistical reasons (Vitek 2015). The typical picture is urgent, watery diarrhoea, often worse in the morning or after fatty meals, in someone whose inflammation markers look fine.

Lactose sensitivity. In a study of 165 people with IBD who were in remission and had no record of lactose sensitivity, about 70% reacted symptomatically to a 50 g lactose challenge, which is a large dose equivalent to roughly a litre of milk (Eadala 2011). The headline number is higher than most clinicians would apply to everyday portions, but the direction is a useful reminder that food intolerance and inflammation are separate problems that can sit on top of each other.

Medication and everything else. Antibiotics, magnesium-containing supplements, artificial sweeteners and new painkillers all cause bowel symptoms in people who have never had Crohn's. Before assuming inflammation, check what changed.

The reason this list matters is that all of these are treatable, and none of them responds to steroids. Chasing a flare that is not there also delays getting help for the thing that is.

When a flare is not diarrhoea at all

Crohn's can involve any part of the gut from the mouth to the anus, and disease that narrows the small bowel produces a completely different pattern from disease in the colon. If your flares announce themselves with bloating, cramping after meals, nausea and even constipation, you are not unusual.

Expert consensus defines a fibrotic stricture as the combination of luminal narrowing, wall thickening and dilation of the bowel upstream, and describes symptomatic strictures in terms of abdominal distension, cramping, dietary restriction, nausea, vomiting, abdominal pain and pain after eating. Strictures affect approximately half of all people with Crohn's at some point, and MRI is considered the optimal way to define them (Rieder 2018).

That changes what a "flare" looks like day to day:

• Pain that arrives 30 to 90 minutes after eating and eases when the meal has passed
• Visible bloating that builds through the day
• Feeling full after very little food
• Nausea, or vomiting undigested food hours after a meal
• Going less often rather than more, sometimes with pellet-like stools
• A growing list of foods that you have learned to avoid because of how they feel going through

People describe exactly this in Crohn's forums. One person in a thread about flare signs mentioned a stricture that had kept them symptomatic for two months straight; another described constipation as their reliable opening act, with the pattern then turning into urgency and mucus (r/CrohnsDisease thread). A separate post from someone with awful symptoms and a normal calprotectin was largely about constipation and bloating severe enough to wake them (r/CrohnsDisease thread).

If you have had surgery, "flare" needs redefining

After an ileal resection, some change in bowel habit is expected rather than a sign of returning disease, and separating the two is genuinely difficult without imaging or endoscopy.

The classic study here followed 89 people who had an ileal resection for Crohn's. Endoscopy found recurrent lesions in the neoterminal ileum within one year in 73% of patients, yet only 20% had symptoms. By three years, 85% had endoscopic recurrence and 34% had symptoms (Rutgeerts 1990). The gap between what the camera saw and what people felt was enormous, and it ran in the direction people least expect: inflammation arrived long before symptoms did.

Practically, that means three things after surgery. Post-operative monitoring is not optional politeness; it is how recurrence gets caught while it is still small. Faster, looser stools can reflect a shorter bowel or bile acid malabsorption rather than inflammation. And a new symptom pattern still deserves investigation, because "it's just my plumbing now" is a conclusion to reach after testing, not before.

Flare, or is my treatment quietly losing its grip?

These are not the same question, and it is worth asking both out loud, because the answers lead to different tests.

Loss of response to maintenance biologic treatment is well documented. A review pooling 16 studies and 2,236 people with Crohn's on infliximab found that on average 37% lost response, working out to roughly 13% per patient-year of treatment (Gisbert 2009). That is a meaningful minority over several years, and it is not a personal failure when it happens.

A thread from someone whose symptoms returned on a newer biologic while their calprotectin was only mildly raised captured the real-world confusion well: was this a small flare, or had the drug stopped working, or had they never truly been in remission in the first place (r/CrohnsDisease thread)? Replies raised several things a team would check, including testing for infection first, looking at drug levels and antibodies, and remembering that a single calprotectin value is not the same as a colonoscopy.

What you can usefully do is bring the timeline rather than the conclusion. When did symptoms start relative to your last dose? Are they worse in the days before the next one? Have you missed or delayed any doses? Has anything else changed, including a new painkiller or a course of antibiotics? Those details are exactly what drives the decision between optimising the current treatment, testing for infection, imaging for a mechanical problem or switching. None of it is a reason to change a dose yourself, and stopping a maintenance treatment without your team is one of the reliable ways to make things worse.

The signals that are not in your gut

Some of the earliest and most specific signs people notice are outside the bowel entirely, and they are frequently left out of flare checklists.

In a nationwide Swiss cohort of 950 people with IBD, 43% of those with Crohn's had between one and five extraintestinal manifestations. Arthritis was the most common at 33%, followed by aphthous mouth ulcers at 10%, uveitis and erythema nodosum at 6% each, and ankylosing spondylitis at 6%. Critically for this question, active bowel disease was independently associated with having an ongoing extraintestinal manifestation in Crohn's, with an odds ratio of 1.95 (Vavricka 2011). European consensus on these manifestations notes that some of them track bowel activity while others run their own course (Harbord 2016).

This is why so many people in Crohn's forums list mouth ulcers, a bloodshot or painful eye, or flaring joint pain as their early warning (r/CrohnsDisease thread). It is not folklore, and it is worth a line in your log.

Two more whole-body signals deserve their own mention:

Fatigue. A systematic review found that between 41% and 48% of people with IBD in remission reported fatigue, and that the evidence on whether fatigue severity tracks disease activity is sparse and conflicting (van Langenberg 2010). So fatigue alone does not confirm a flare, but a clear change in your own fatigue is a legitimate thing to report rather than push through.

Anaemia. Iron deficiency and anaemia are common in IBD and have their own European consensus on diagnosis and management (Dignass 2015). New breathlessness on stairs, unusual pallor or a heart that races on mild exertion are worth a blood test rather than a shrug, and should be mentioned to a doctor promptly.

The tests that actually settle it

Faecal calprotectin is the workhorse, blood CRP is useful but blunter in Crohn's than people assume, and imaging or endoscopy is what confirms the picture when the stakes are high.

Faecal calprotectin. In a meta-analysis of 19 studies covering 2,499 people with symptoms suggesting active IBD, pooled sensitivity for endoscopic activity was 0.88 for calprotectin against 0.49 for CRP, although calprotectin's specificity was lower at 0.73 against CRP's 0.92. The authors also noted calprotectin was more sensitive in ulcerative colitis than in Crohn's (Mosli 2015). Translated: a raised calprotectin is a strong prompt to look further, and a normal one makes significant inflammation a lot less likely without ruling it out entirely, particularly for small bowel disease.

A separate study put numbers on the thresholds in Crohn's. A calprotectin at or below 250 µg/g predicted endoscopic remission with 94.1% sensitivity and a negative predictive value of 96.6%, while a result above 250 µg/g indicated large ulcers with 60.4% sensitivity and 79.5% specificity (D'Haens 2012). Laboratory cut-offs vary, so the number your lab uses matters more than any number in an article.

Blood CRP. CRP correlates reasonably well with disease activity in Crohn's, better than it does in ulcerative colitis, where the response can be modest or absent despite active inflammation (Vermeire 2004). But as the meta-analysis above shows, roughly half of symptomatic people with endoscopic activity will have a CRP that does not flag it. A normal CRP is reassuring, not conclusive.

Imaging and endoscopy. European diagnostic guidance sets out how cross-sectional imaging, endoscopy and biomarkers fit together for monitoring known IBD and detecting complications (Maaser 2019), and national guidance in the UK was refreshed for Crohn's disease in 2025 (Butler 2025). Intestinal ultrasound is worth asking about where it is available: in a prospective study across 47 German centres, 234 adults with a Crohn's flare were followed with bowel ultrasound and showed significant improvements in bowel wall thickness, stratification and Doppler signal by three and twelve months after treatment was intensified (Kucharzik 2017). It is quick, involves no radiation and no preparation, and can be repeated.

Why testing beats waiting it out

Managing Crohn's on symptoms alone produces worse outcomes than managing it on symptoms plus markers, and that has been tested directly in a randomised trial.

The CALM trial randomised 244 adults with active Crohn's to two monitoring strategies. Both groups escalated treatment in the same stepwise way. The difference was the trigger. The clinical management group escalated on symptoms. The tight control group escalated on symptoms or a faecal calprotectin at or above 250 µg/g or a CRP at or above 5 mg/L or recent steroid use. At week 48, 46% of the tight control group had reached the primary endpoint of mucosal healing, against 30% of the clinical management group, an adjusted risk difference of 16.1% (Colombel 2017).

Adding objective markers to symptoms changed outcomes. That is the best argument there is for picking up the phone when you suspect a flare rather than giving it another fortnight.

Older work points the same way. In 80 people with IBD in clinical remission followed for a year, faecal calprotectin measured while they were well predicted who would relapse, and 58% of the Crohn's group did relapse over that period (Tibble 2000). Inflammation was measurable before symptoms declared themselves.

This cuts both ways, and the second direction upsets people more. Someone in r/CrohnsDisease described mild symptoms, mostly mucus and bloating, with no diarrhoea or blood, and a calprotectin around 3,000 (r/CrohnsDisease thread). Feeling all right is not evidence of a quiet bowel. It is one reason many teams check markers on a schedule rather than only when you complain.

What tips a quiet Crohn's into an active one

Often nobody can name a single cause, and it is worth saying that plainly so you stop hunting for the meal that did it. But several factors have real evidence behind them, and they are the ones your team will ask about.

Missed or delayed treatment. This is the first thing most IBD teams check, and it is a conversation to have rather than a confession to avoid. If treatment is hard to take because of cost, side effects, needle anxiety or appointments you cannot get to, say so; that is a problem with solutions.

Infection. C. difficile in particular, as above (Rodemann 2007).

NSAID painkillers. In an internet-based cohort of 791 people with IBD in remission, those with Crohn's using NSAIDs at least five times a month had a higher rate of active disease six months later, 23% against 15%, with an adjusted risk ratio of 1.65. Interestingly, regular paracetamol use showed a similar association, which the authors suggested might partly reflect people already having more symptoms rather than the drug causing them (Long 2016). Less frequent NSAID use was not associated with active disease. Do not change any painkiller on your own; ask what is sensible for you.

Poor sleep. Among 1,291 people whose Crohn's was in remission at baseline, those with impaired sleep had double the odds of active disease six months later, with an adjusted odds ratio of 2.00. No such effect was seen in ulcerative colitis (Ananthakrishnan 2013). This is one of the few findings in this article that is specific to Crohn's rather than IBD in general.

Mood. In a two-year prospective study of 405 people with IBD, those whose disease was quiescent at baseline but who had abnormal anxiety scores were more likely to need steroids or have a flare later, with a hazard ratio of 2.08, and more likely to need treatment escalation, hazard ratio 1.82. The relationship ran in both directions: active disease at baseline predicted abnormal anxiety scores later (Gracie 2018). In a separate population-based study that surveyed people with IBD every three months, high perceived stress was the only factor independently associated with a later symptomatic flare (Bernstein 2010).

Smoking. Smoking behaves differently in Crohn's than in ulcerative colitis. In an intervention study of 474 smokers with Crohn's, the 59 who quit for more than a year had a risk of flare no different from people who had never smoked, and lower than those who kept smoking (Cosnes 2001).

Food is conspicuously absent from that list as a cause of new inflammation, although it is a very real cause of symptoms. Our article on whether food can trigger a flare unpacks that distinction in detail, and coffee and Crohn's covers one of the most argued-about individual items.

A worked example: three weeks, one phone call

The practical skill is turning a vague fortnight into four numbers and one question. Here is what that looks like.

Background. Daniel has ileal Crohn's, had a right hemicolectomy four years ago, and has been on a maintenance biologic since. His written baseline from last spring reads: three stools a day, none overnight, pain rarely above 3, no blood.

Week one. He notices he is going five or six times a day and is woken once. Pain after dinner reaches 6 twice. He assumes it is the takeaway on Friday and cuts out dairy.

Week two. Still five to six a day, still no blood, and now two nights disturbed. He is exhausted in a way that a weekend does not fix, and has lost about two kilograms without trying. A mouth ulcer appears. Cutting dairy has changed nothing.

Week three, the useful bit. Instead of another elimination experiment, Daniel writes four lines:

• Stools: baseline 3 a day, now 5 to 6, for 17 days
• Overnight: baseline none, now 3 to 4 nights a week
• Pain: baseline under 3, now reaching 6 after meals
• Blood: none. Weight: down 2 kg. New mouth ulcer. No missed doses. No antibiotics. Took ibuprofen twice for a headache.

He calls the IBD nurse line and reads that out. The response is concrete: a stool sample for calprotectin and infection including C. difficile, a blood test for CRP and full blood count, and an appointment brought forward. His calprotectin comes back at 640 µg/g and his CRP is mildly raised, so the team arranges an intestinal ultrasound and discusses options with him.

The alternative ending. Suppose calprotectin had come back at 40 µg/g and stool cultures were clear. That would not mean nothing is happening. With a previous ileocaecal resection, bacterial overgrowth and bile acid malabsorption both move up the list (Shah 2019, Vitek 2015), and IBS-type symptoms affect roughly a third of people with Crohn's in remission (Fairbrass 2020). The next question becomes "what else could be doing this", not "is anything doing this".

Either way, the phone call happened in week three rather than week ten, and it happened with numbers rather than adjectives. If you keep your log in an app, Clairop is built around this handover: it turns what you log into a one-page visit report with your activity score, bowel pattern, medication adherence and lab results, and its method page explains why it waits for repeated observations before calling anything a pattern. A sheet of A4 in your handwriting does the same job.

Myths that make this harder

Myth: "If it were a real flare, I'd know." Endoscopic recurrence after ileal resection appeared in 73% of patients within a year while only 20% had symptoms (Rutgeerts 1990). Feeling fine is not evidence.

Myth: "A normal calprotectin means I'm making it up." Calprotectin is less sensitive in Crohn's than in ulcerative colitis, and it reflects the gut lining rather than everything that can go wrong (Mosli 2015). A normal result narrows the list; it does not close the case.

Myth: "No diarrhoea means no flare." Stricturing disease typically presents with distension, cramping, nausea, vomiting and pain after eating (Rieder 2018).

Myth: "My last colonoscopy was clean, so this cannot be a flare." A scope describes one day and the segments it reached. That point comes up repeatedly in Crohn's communities, and it is correct (r/CrohnsDisease thread).

Myth: "Flares are caused by something I ate." Diet affects symptoms considerably. The factors with actual evidence for tipping Crohn's into activity are missed treatment, infection, regular NSAIDs, poor sleep, stress and smoking (Long 2016, Ananthakrishnan 2013, Bernstein 2010, Cosnes 2001).

Myth: "I should wait and see if it settles." The trial that compared waiting on symptoms with acting on symptoms plus markers found the marker-guided approach produced substantially more mucosal healing at a year (Colombel 2017).

Myth: "Fatigue on its own means I'm flaring." Between 41% and 48% of people with IBD in remission report fatigue (van Langenberg 2010). A change in your fatigue is worth reporting; its presence alone does not settle anything.

Myth: "If the biologic were working, I would never have symptoms." This one came up in a Crohn's thread with people on both sides. The honest position is that persistent symptoms deserve investigation rather than acceptance, and that investigation may find inflammation, infection, a stricture or something non-inflammatory (Gisbert 2009).

When to contact your IBD team, and when not to wait

Contact your IBD team promptly rather than riding it out if anything on this list is true. None of these is a reason to change your own treatment.

Contact your team within a few days if you have:

• Stool frequency above your usual baseline for more than about a week
• New or increasing blood in your stool
• Symptoms that wake you at night
• New abdominal pain, particularly pain that comes on after eating
• Unintended weight loss, or eating much less because of symptoms
• New mouth ulcers, a painful or red eye, new joint pain or a new skin lesion
• Fatigue or breathlessness that is clearly worse than your normal
• Recent antibiotics, a household stomach bug, or regular use of NSAID painkillers alongside worsening symptoms
• Any missed doses of maintenance treatment
• Symptoms that have returned within weeks of a treatment change

Seek urgent same-day medical help if you have:

• Severe abdominal pain, or a swollen, tender abdomen
• Repeated vomiting, especially with no wind or stool passing
• A fever, a racing heart, feeling faint or confused
• Heavy rectal bleeding or passing clots
• New pain, swelling or discharge around the anus, which can indicate an abscess
• Signs of dehydration such as very little urine, dizziness on standing, or being unable to keep fluids down

Guidance for managing Crohn's in adults sets out how flares are assessed and treated, including checking for infection and complications before escalating treatment (Lichtenstein 2018, Butler 2025). None of it is something to work out alone at 2am.

When you do make contact, lead with the numbers: stools per day now against your baseline, overnight episodes, days with blood, weight change, any new outside-the-gut symptoms, recent infections or antibiotics, painkiller use, and any missed doses. If you want help structuring that conversation, our guide to questions to ask your doctor about Crohn's disease covers what to ask once the tests are back, and our Crohn's disease guides collect the rest.

The bottom line is unglamorous. You cannot tell whether you are in a Crohn's flare by how it feels, and neither can anybody else. What you can do is notice a change against your own written normal, take the look-alikes seriously, and hand your team numbers early enough for a test to be worth doing.