Crohn’s Disease Symptoms and Flare-Ups: What to Watch For

By Anna Curran, RN, BSN, PHN · Last reviewed October 2026

The most common Crohn’s disease symptoms are diarrhea, belly pain and cramping, and weight loss. Many people also feel very tired, lose their appetite or run a fever. Symptoms tend to come and go, with active times called flares and calm times called remission.

Knowing your own pattern helps you catch a flare early and know when you need help fast. Here is what to watch for.

Common Crohn’s Disease Symptoms

Crohn’s disease symptoms depend on where the inflammation is in your digestive tract and how severe it is. Two people with Crohn’s can have very different experiences.

According to NIDDK and Mayo Clinic, symptoms in the gut can include:

Diarrhea, often ongoing
Belly pain and cramping
Weight loss without trying
Low appetite
Nausea and vomiting
Blood in the stool
Mouth sores
Pain or drainage near the anus, which can be a sign of a fistula (a tunnel from the bowel to the skin)

Whole-body symptoms are common too:

Fatigue that does not go away with rest
Fever
Anemia, which can make you feel weak, tired or short of breath

Symptoms Outside the Gut

Crohn’s is not only a gut problem. The inflammation can affect other parts of your body. You might notice:

Joint pain or soreness
Red, painful or irritated eyes
Red, tender bumps under the skin
Skin sores or rashes
Kidney stones
Bone loss
Liver or bile duct problems

In children and teens, Crohn’s can slow growth or delay puberty. A child who is not gaining weight or growing as expected should be checked by their doctor.

Tell your care team about these symptoms even if they seem unrelated. They can be part of your Crohn’s, and many can be treated.

What a Flare Feels Like

A flare is when symptoms come back or get worse after a calm period. The Crohn’s & Colitis Foundation lists these common signs of a flare:

More frequent or urgent bowel movements
Diarrhea
Bloody stool
Belly pain
Nausea and vomiting
Weight loss
Fatigue, low appetite, body aches, joint pain, rashes or eye problems

Flares can build slowly over days or come on fast. You may notice small changes first, like an extra trip to the bathroom each day or feeling more drained than usual.

Keep a simple symptom log

A short daily log can help you and your doctor see patterns. Write down:

How many bowel movements you had and what they looked like
Any blood or mucus
Pain level from 0 to 10
Energy level
Fever, if any
What you ate and drank
Medicines you took, including any missed doses

Bring your log to your visits. It gives your doctor real details instead of guesses.

Possible Flare Triggers

Flares can happen even when you do everything right. Still, some things are known to stir up symptoms. The Crohn’s & Colitis Foundation points to these:

Missed or changed medicine doses. Skipping doses or stopping medicine can lead to a flare. Talk with your doctor before making any change.
NSAIDs. Aspirin, ibuprofen and naproxen can irritate the bowel. Ask your doctor or pharmacist which pain reliever is right for you.
Antibiotics. These can upset the balance of gut bacteria. Tell your doctor if your symptoms flare while you are taking one.
Smoking. Smoking is linked to more active Crohn’s disease and more flares.
Stress. Stress does not cause Crohn’s, but it can make symptoms feel worse.

An infection, such as a stomach bug, can also look like a flare. That is one reason your doctor may order tests when your symptoms change.

What to Do When You Think You Are Flaring

If you notice signs of a flare:

Call your gastroenterologist’s office. Many offices want to hear from you early. They may adjust your treatment or order tests, such as stool or blood tests.
Keep taking your medicines as prescribed unless your doctor tells you otherwise.
Drink fluids often. Diarrhea can quickly lead to dehydration. Sip water, broth or an oral rehydration drink through the day.
Eat small, simple meals. Gentler, lower-fiber foods may be easier on your gut during a flare.
Rest when you need to. Fatigue during a flare is real. Short rests can help you get through the day.
Ease stress where you can. Slow breathing, a short walk, calming music or writing in a journal may help you feel more settled.

It is also worth calling if your treatment does not seem to be working, if you have a fever or signs of infection, or if you are losing weight without trying.

When to Call Your Doctor

MedlinePlus lists these reasons to contact your provider:

Very bad belly pain
Diarrhea that diet changes and medicine do not control
Weight loss, or a child who is not gaining weight
Rectal bleeding, drainage or sores
A fever that lasts more than 2 or 3 days, or a fever over 100.4°F (38°C) without another illness to explain it
Nausea and vomiting that last more than a day
Skin sores that do not heal
Joint pain that keeps you from daily activities
Side effects from your medicines

Emergency Warning Signs

Some symptoms need care right away. Call 911 or go to the emergency room if you have:

Signs of a bowel blockage: cramping belly pain, a swollen belly, vomiting, and not being able to pass gas or stool
Severe or constant belly pain
Heavy rectal bleeding or blood clots in your stool
Vomiting so much you cannot keep liquids down
A high fever (above 100.3°F, per the Crohn’s & Colitis Foundation) along with other flare symptoms
Signs of severe dehydration, such as dizziness, a racing heart, confusion, or passing little or no urine

A bowel blockage is a serious problem. Mayo Clinic warns that an untreated blockage can cause tissue death and infection. Do not wait to see if it passes.

If you have a fever with new pain, swelling or drainage near your anus or belly, call your doctor the same day. This can be a sign of an abscess, which is a pocket of infection.

Frequently Asked Questions

How long does a Crohn’s flare last?

It varies a lot. Some flares last a few days, and others last weeks or longer. Call your doctor early, because treatment can often help shorten a flare.

Can Crohn’s disease symptoms come and go?

Yes. Most people have flares and periods of remission. Remission can last weeks or years, but it is still important to keep taking your medicine and seeing your doctor.

Is fatigue a symptom of Crohn’s disease?

Yes. Fatigue is very common. It can come from inflammation, anemia, poor sleep or not getting enough nutrients, so tell your doctor if you feel drained.

Can I take ibuprofen for Crohn’s pain?

NSAIDs like ibuprofen, naproxen and aspirin can make Crohn’s worse. Acetaminophen is often recommended for mild pain instead. Ask your doctor or pharmacist what is safe for you.

The Bottom Line

Crohn’s disease symptoms most often include diarrhea, belly pain and weight loss, but they can also affect your joints, skin and eyes. Flares are times when symptoms return or worsen, and catching them early gives you and your doctor more options. Keep a simple symptom log and call your care team when things change. Go to the ER right away for signs of a blockage, heavy bleeding, constant pain or vomiting that keeps you from holding down liquids.