What’s Actually Happening in Your Body With Interstitial Cystitis (IC/BPS)?

If you’ve been told “your urine test is clear” while your bladder feels like it’s on fire, you are not imagining it.

You might already have read our basic overview: What is Interstitial Cystitis (IC) and Bladder Pain Syndrome?. That article explains what IC/BPS is and how it’s diagnosed.

This post goes a step deeper. Here, we’ll look at what’s actually happening inside your body – in your bladder lining, pelvic floor and nervous system – so your symptoms start to make more sense, and you feel less like your body is randomly betraying you.

If you’d like to go deeper, there’s a free downloadable ebook at the end:

IC Ally Foundations: What’s Actually Happening With Your Bladder (and How to Start Taking It Back)

Quick recap: Interstitial Cystitis / Painful Bladder Syndrome (IC/BPS) in one paragraph

In simple terms, Interstitial Cystitis / Bladder Pain Syndrome (IC/BPS) is long-lasting bladder-related pain, pressure or discomfort, plus urinary symptoms like urgency and frequency, when tests don’t show another clear cause like infection or stones. For a fuller overview of symptoms, diagnosis and treatment options, you can read our guide What Is Interstitial Cystitis (IC) and Bladder Pain Syndrome?

Now, let’s look at what’s actually happening inside your body when you live with IC/BPS.

The three big symptom clusters

Most people with IC/BPS recognise themselves in at least one of these areas:

1. Pain

• Burning in the urethra (the tube you pee from)

• Deep ache or pressure in the bladder or pelvis

• Pain that changes as your bladder fills or after you empty it

2. Urgency

• That “I need a toilet right now” feeling

• Struggling to comfortably delay urinating

• Sometimes small leaks if you can’t get there in time

  
  

3. Frequency

• Going far more often than feels reasonable

• Waking multiple times at night

• Planning your day around toilet access

You might be pain-dominant, urgency/frequency-dominant, or a mix. There is no single “correct” way to have IC/BPS.

What’s happening inside the bladder?

There are a few key ideas that can help the puzzle make more sense.

1. The bladder lining can be irritated or “leaky”

The inside of your bladder is lined with specialised cells and a thin protective coating (often called the GAG layer). That coating helps stop irritating substances in urine from soaking into deeper tissue.

In IC/BPS, this barrier is thought to be less effective in some people. When that happens:

• Substances in urine can reach nerve endings and immune cells

• Those nerves send urgent “there’s a problem” signals

• You can feel pain, burning, urgency – even without an infection

  
  

You did not cause this by being “too sensitive”. It’s a physical, biological process.

2. Mast cells and histamine can drive urgency

Inside the bladder wall live mast cells – immune cells that release histamine and other chemicals when they think there’s a threat (similar to an allergy response).

When they’re activated:

• The bladder wall can become swollen and irritated

• Stretch-sensitive nerves may fire long before the bladder is truly full

• The brain hears “we’re full and unhappy – empty now!”

  
  

You experience that as urgent, frequent trips to the toilet – sometimes with very little urine each time.

3. The trigone, urethra and hormones

The trigone is a triangular area at the base of the bladder, where the ureters enter and the urethra leaves. In some people, tissues here (and in the urethra) are influenced by oestrogen levels.

When these tissues are thin, dry or fragile (for example after menopause or certain treatments):

• They can become more easily irritated by urine

• Concentrated urine tends to “sit” in this lowest part

• You might feel burning or stinging especially at the end of urination

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For some, local vaginal/urethral oestrogen (prescribed by a clinician) becomes one piece of the puzzle. It’s not for everyone, but it’s useful to understand why that conversation sometimes comes up.

4. The bladder–brain loop

All of this feeds into a feedback loop:

1. The lining is irritated

2. Mast cells release histamine → swelling and inflammation

3. Nerves send louder “danger” signals to the brain

4. The brain responds by sending stronger “contract now” messages to the bladder

5. You feel pain, urgency, frequency – and sometimes spasms

6. Over time, the whole system becomes more reactive

   
   

Understanding this loop can be strangely comforting: your body isn’t random or broken, it’s over-protecting you.

Beyond the bladder: pelvic floor and nervous system

IC/BPS is not just a bladder issue. Two big players are often missing from the standard explanation.

The pelvic floor

The pelvic floor is a group of muscles at the base of your pelvis that:

• Support your bladder, uterus and bowel

• Help control wee and poo

• Support sexual function

When you’ve been in pain or frightened of leaking for a long time, these muscles often shift into constant “guarding” mode – tight, overactive, and struggling to relax.

That can show up as:

• Difficulty starting the flow of urine

• Pushing or straining to pee

• A sense of not emptying fully

• Deep pelvic, vaginal, rectal or tailbone pain

• Pain with penetration or pelvic exams

  
  

This doesn’t mean “it’s all muscular now”, but it does mean the muscles usually need help to learn to soften again.

The brain and pain volume

Your brain’s job is to protect you. When it receives repeated danger signals from the bladder and pelvis, it adapts by turning the pain volume up:

• Pain pathways become more sensitive (a concept called central sensitisation)

• Mild triggers can feel severe

• Pain sometimes continues even as tissues begin to heal

That doesn’t make the pain psychological or imaginary. It means the nervous system itself has become part of the condition – and it can be supported, not blamed.

Breathwork, gentle movement, better sleep routines, therapy, and certain medical treatments all aim, in different ways, to help turn that volume back down.

First steps: from confusion to investigation

There’s no single protocol that works for everyone with IC/BPS. But you can absolutely move from feeling helpless to feeling more informed and intentional.

Here are some gentle starting steps:

1. Name your current pattern

Try finishing these sentences:

• “Right now, my IC/BPS feels mostly __________________.”

• “The three things that affect my daily life the most are:

  1. __________________

  2. __________________

  3. __________________

This isn’t about labels – it’s about describing your reality clearly.

2. Track like an investigator, not a judge

Instead of blaming your body for every flare, treat your symptoms as data.

You might track:

• Pain, urgency, frequency (0–10 scales)

• Toilet trips and rough volumes

• Foods and drinks

• Movement/sitting

• Stress levels, sleep, hormones

Then look for patterns over time, not overnight. For example:

• “My urgency spikes after several bad sleep nights.”

• “Long sitting days increase my pelvic pain.”

• “Certain drinks nearly always trigger a flare for me.”

  
  

3. Build a few “support pillars”

You don’t need a perfect plan to begin. You just need some pillars to lean on while you explore.

Examples (always in conversation with your own clinician):

• Knowledge & self-compassion – reminding yourself your symptoms have a real basis, and your body is trying (clumsily) to protect you.

• Bladder-calming basics – steady hydration, gentle experiments with bladder-friendly choices, noticing which drinks/foods are sharpest for you.

• Pelvic floor & body support – exploring down-training (relaxing) techniques, and pelvic health physiotherapy if available.

• Nervous system support – small, frequent moments of safety for your body: breathing, rest, pacing, soothing routines.

• Targeted medical treatments – medications, bladder instillations, nerve-based therapies, chosen deliberately rather than in panic.

Want a deeper, calmer walkthrough? Download the free IC Ally ebook

This blog is a starting sketch. If you’d like a more structured, gentle guide you can print, highlight and bring to appointments, you can download:

IC Ally Foundations: What’s Actually Happening With Your Bladder (and How to Start Taking It Back)

A free, educational PDF ebook

Inside, you’ll get:

• A clearer explanation of pain, urgency and frequency in IC/BPS

• Simple, friendly diagrams of what’s happening inside the bladder

• Sections on the pelvic floor, the brain and pain volume, and whole-body links

• Reflection pages to help you describe your own pattern

• A step-by-step framework for starting your own IC investigation roadmap

• 
  

👉 “Click below to get the free ebook.”

IC-Ally-Foundations whats happying in the body.pdf

Download PDF • 1.43MB

You are not starting from zero. You’re starting from everything you’ve already survived.This is just the next step: understanding your body more clearly, so you can support it more kindly.

Frequently Asked Questions About What’s Happening in IC/BPS

1. Can you have Interstitial Cystitis even if your urine tests are clear?

Yes. Many people with Interstitial Cystitis / Bladder Pain Syndrome (IC/BPS) have normal urine tests. In IC/BPS, symptoms can be driven by changes in the bladder lining, immune cells like mast cells, pelvic floor muscles and the nervous system, rather than by an active infection.

2. Why does my bladder feel full even when very little comes out?

That “false fullness” feeling can happen when the bladder wall is irritated or swollen. Sensitive nerves in the bladder can start sending “we’re full and unhappy” signals to the brain long before the bladder truly holds much urine, which you experience as urgency and frequent trips to the toilet.

3. How can the pelvic floor affect IC/BPS symptoms?

The pelvic floor muscles sit underneath and around the bladder. When they become tight or overactive (often as a protective response to pain or fear of leaking), they can make it harder to relax and empty the bladder and can add their own pain and pressure. This can mimic or amplify IC/BPS symptoms.

4. Is the pain in IC/BPS “all in my head”?

No. The pain is real. Over time, repeated pain and threat signals from the bladder and pelvis can make the nervous system more sensitive, like turning the volume up on a stereo. This is called sensitisation. Brain-based approaches don’t deny the physical reality of the condition; they aim to help turn that volume back down alongside other treatments.

Further reading & support

If you’d like to explore more about IC/BPS and related conditions, these resources are a good starting point:

• NHS – Bladder pain syndrome (BPS)

  Clear, patient-friendly overview of symptoms, diagnosis and treatment options for BPS/IC.→ Search for: “Bladder pain syndrome BPS NHS”

• International Painful Bladder Foundation – Patient booklet

  A free PDF booklet on Interstitial Cystitis/Bladder Pain Syndrome, hypersensitive bladder and Hunner lesions, written for patients and families.

• York and Scarborough Teaching Hospitals – Bladder Pain Syndrome leaflet

  UK hospital patient leaflet (updated 2024) explaining BPS/IC, investigations and management options.→ Search for: “Bladder Pain Syndrome (Interstitial Cystitis) York Scarborough leaflet”

• International Continence Society (ICS) – IC/BPS terminology page

  For those who like the technical language: how international experts currently define IC/BPS and related terms

  
  

References & clinical guidelines (for deeper reading)

These are more technical, but useful if you want to read what guidelines and reviews say, or if you’re sharing this blog with clinicians:

1. American Urological Association (AUA) – Diagnosis and Treatment of Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS), 2022 guideline.Comprehensive clinical guideline covering diagnosis, phenotyping and a multimodal approach to treatment, with an emphasis on patient education and individualised care.

2. StatPearls – Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS), updated 2024.Up-to-date clinical review summarising epidemiology, pathophysiology (including bladder lining, mast cells and central sensitisation) and management strategies, aligned with AUA recommendations.

3. EAU Guidelines on Chronic Pelvic Pain (section on primary bladder pain syndrome).European Association of Urology guideline describing definitions, diagnostic principles and management of primary bladder pain syndrome within the wider chronic pelvic pain framework.

4. RCOG Green-top Guideline No. 70 – Management of Bladder Pain Syndrome.Royal College of Obstetricians and Gynaecologists guideline aimed at primary and secondary care clinicians, focusing on symptom patterns, investigations and stepwise management of BPS in people assigned female at birth.

5. International Painful Bladder Foundation – “Interstitial Cystitis/Bladder Pain Syndrome, Hypersensitive Bladder, Hunner Lesion” (patient booklet, 2023).Patient-centred overview of definitions, diagnostic approaches and management options, with practical coping information.

6. NHS – Bladder pain syndrome (BPS).Current NHS summary of bladder pain syndrome/IC, including symptom description, typical investigations and an overview of available treatments.