What Are the First Signs of a Diverticulitis Flare And What Should You Do?

Disclaimer: This article does not constitute medical advice. Medical advice should always be sought from a qualified medical practitioner.

This article is based on anonymised discussions from our Diverticulitis Club group on Facebook, combined with current clinical guidance and patient experience.

For most people, the first sign of a diverticulitis flare is pain in the lower abdomen, most commonly on the left side. However, our community discussions show that symptoms can vary widely. Some people experience right-sided pain, back pain, bloating, constipation, diarrhoea, nausea, urinary symptoms or even headache before the abdominal pain becomes obvious.

Just as importantly, there is confusion about what to do when these symptoms begin.

Below, we bring together the experiences shared in our community and set them alongside current understanding of diverticular disease.

Is Left-Sided Pain Always the First Sign?

Often, but not always.

Many members described a familiar pattern:

• Dull ache in the lower left abdomen
• Increasing tenderness
• Bloating and wind
• Change in bowel habits

“Margaret from Lancashire” described it simply as “pain in the left side.”
“June from Kent” said the same.

This aligns with medical understanding. In the UK, diverticulitis most commonly affects the sigmoid colon, which sits on the lower left side.

However, several members reported right-sided pain.

“Andrew from Devon” said his flares begin with right-sided pain and bloating.
“Madeline from Birmingham” added, “Everyone gets left side pain. I always get the right side.”

Right-sided diverticulitis is less common in Western populations but does occur. Pain patterns can also reflect referred pain or individual anatomy.

Can Back Pain Be an Early Warning Sign?

Yes.

A number of members reported back pain before abdominal pain.

“Roxanne from Cardiff” described severe right lower back pain that later moved to the front.
“Dennis from Essex” said the pain starts in his back and travels around to the left side.
“Brenda from York” mentioned hip pain when her flare becomes severe.

This can be confusing, particularly for those who initially suspect kidney issues or musculoskeletal problems. Lower back discomfort alongside abdominal symptoms should not be ignored, especially if you have a history of diverticulitis.

What About Bloating, Gas and Bowel Changes?

For many, the first sign is not pain but pressure.

Members described:

• A sensation of a balloon inflating in the lower abdomen
• Excessive wind
• Constipation
• Diarrhoea
• Alternating constipation and diarrhoea

“Bev from Nottingham” described the feeling as “someone inflating a balloon inside me until it feels like it will explode.” She admitted she feared cancer before receiving a diagnosis.

Several members mentioned constipation first, followed by cramps. Others experienced diarrhoea early on.

It is worth noting that these symptoms overlap with irritable bowel syndrome. “Nancy from Surrey” shared that she also has IBS and found the symptoms almost identical. Her flare was only identified through a CT scan performed for another reason.

This overlap adds to the uncertainty many feel. Is this IBS? Something I ate? Or a flare?

Are There Less Obvious Early Symptoms?

Yes, and these can catch people off guard.

Some members reported:

• Headache before abdominal pain
• Feeling feverish
• Nausea
• Loss of appetite
• Dry mouth
• Increased urinary urgency
• A pounding or racing heart

“Jean from Oxford” said a dull headache is her first clue.
“John from Norfolk” mentioned urinary urgency with lower abdominal discomfort.
“Mary from Bristol” described her heart pounding, which she found frightening.

Inflammation in the pelvis can irritate the bladder, explaining urinary symptoms. Systemic inflammation can cause general unwellness, fatigue and feverish feelings.

How Quickly Can a Flare Become Serious?

This is where community experience becomes especially important.

One anonymous member described mild side pain and unusual shooting pains which she initially attributed to menopause. She continued working, hosted a party and felt embarrassed about seeking help. Within days, she was admitted to hospital with a sealed perforation and sepsis from burst abscesses.

She described feeling traumatised afterwards and now seeks help much earlier.

While most flares are uncomplicated, complications such as abscess, perforation or sepsis can occur. According to the NHS, you should seek urgent medical attention if you experience:

• Severe or worsening abdominal pain
• High temperature
• Persistent vomiting
• Blood in stools
• Signs of sepsis such as confusion or extreme weakness

You can read more about complications on the NHS website:
https://www.nhs.uk/conditions/diverticular-disease-and-diverticulitis/

What Do People Do At the First Sign of a Flare?

This was the second half of the original question, and many members felt it was overlooked.

Common self-management strategies shared included:

1. Switching to Clear Liquids

Several members move to clear liquids for two to three days at the first sign of pain. Broths, water and weak tea were commonly mentioned.

2. Moving to Soft or Low Residue Foods

After initial rest, members reported introducing:

• Scrambled eggs
• Cottage cheese
• Tinned fruit
• Light soups

“Monica from Leeds” follows a low residue diet and takes antibiotics when prescribed.

3. Gentle Movement

A few members mentioned walking to relieve gas and reduce bloating.

4. Warmth

Heat pads were frequently mentioned to ease cramps.

5. Pain Relief

Paracetamol was commonly recommended within safe dosing limits. Some mentioned co-codamol but were mindful of constipation.

It is important to note that non-steroidal anti-inflammatory drugs such as ibuprofen are often discouraged in diverticular disease due to potential increased risk of complications. Always check with a healthcare professional before taking medication.

6. Seeking Medical Review

Those who had experienced severe complications stressed the importance of early medical review rather than “pushing through”.

When Should You Not Try to Manage It Yourself?

You should seek medical advice urgently if:

• Pain is severe or escalating
• You develop fever
• You feel faint or confused
• You have persistent vomiting
• You notice significant bleeding

One member wrote simply, “I always end up in hospital with it.” For some, early intervention prevents escalation.

Why Does It Feel So Unpredictable?

Because it is.

Symptoms vary in:

• Location
• Intensity
• Speed of onset
• Associated features

Some flares remain mild and settle within days. Others progress rapidly.

For people over 50, this unpredictability can be deeply unsettling. You may already be managing other health conditions. You may be caring for grandchildren or ageing parents. The idea of sudden hospital admission is frightening.

Understanding your own early warning signs, and having a plan agreed with your GP, can restore a sense of control.

Frequently Asked Questions

Key Takeaways

• Lower left abdominal pain is the most common first sign, but right-sided and back pain are reported.
• Bloating, constipation, diarrhoea and nausea frequently precede or accompany pain.
• Symptoms can overlap with IBS.
• Early medical review is important if symptoms escalate.
• Many people use short-term dietary adjustment and paracetamol under guidance, but management should be personalised.

If you are learning your own early warning signs, you are not alone. Our forum brings together people who are navigating exactly these questions, sharing practical experience alongside evidence-based information.

You can join the discussion here:
https://diverticulitis.club/forum/

Disclaimer: This article does not constitute medical advice. Medical advice should always be sought from a qualified medical practitioner.