What is interstitial cystitis (IC)?

Interstitial cystitis is a urologic (bladder-related) pain condition. In addition to being a tongue-twister to pronounce, interstitial cystitis (IC) also goes by a few other names: painful bladder syndrome (PBS) and urologic chronic pelvic pain syndrome (UCPPS). We’ll use “IC” as a catch-all term in this article because it is still the most commonly used name for the condition.

As its alternative names imply, IC is chiefly characterized by chronic pelvic pain. Its symptoms are wide-ranging and variable, though many people with the condition will experience a common constellation of bladder/urinary complaints, including:

  • Pain originating from the bladder region
  • Urinary urgency (an intense, “gotta go now” sensation of needing to pee)
  • Frequent urination 

If you’ve had urinary tract infections (UTIs), these symptoms may sound familiar. IC and UTI share the same set of symptoms. However, no infection can be identified in people with IC, and their symptoms don’t respond to antibiotic treatment. 

According to the American Urologic Association, an IC diagnosis can be considered when symptoms have been present for more than six weeks. This criterion can complicate diagnosis, however, given that IC symptoms often come and go in varying intensities. Exacerbations, or “flares”, of IC symptoms can be mistaken for recurrent infections and lead providers to prescribe repeating courses of antibiotics.

Who is affected by IC?

IC is most commonly diagnosed in people assigned female at birth (AFAB). People born with penises can be affected by similar symptoms, but physicians classically have given them the diagnosis of chronic prostatitis (CP), aka chronic pelvic pain syndrome (CPPS). Recently, the significant overlap between the symptoms of IC/PBS and CP/CPPS led researchers to propose the all-inclusive term UCPPS, which can be applied regardless of one’s genital anatomy.

Researchers estimate that approximately 2.7 to 6.5% of AFAB folks live with IC, though many have not been formally diagnosed. In the United States, this equated to an estimated 3.3 to 7.9 million women (aged 18+) affected by the condition (as of 2011). Given our incomplete understanding of IC and the frequency with which diagnosis is missed or incorrect, the condition may be even more prevalent than predicted in the research.

What causes IC?

The biomedical system still does not fully understand what causes IC. As such, it is considered a “diagnosis of exclusion” meaning:, which means that medical providers must first rule out other potential conditions that could be causing a patient’s symptoms before diagnosing them with IC. Other diagnoses they must consider range from UTIs and STIs (sexually transmitted infections) to allergic reactions and cancer

As you may imagine, this can lead to a long, drawn-out diagnostic process involving extensive testing and often, a fair amount of worry. IC diagnosis is further complicated by the fact that the condition may have different causes in different people. Many medical syndromes behave this way, with multiple distinct causes resulting in similar symptoms: the common cold, which can be caused by hundreds of different viruses, is an excellent example of this phenomenon.

Let’s consider a few current hypotheses behind the causes of IC: 


To date, no specific genetic mutation has been linked to IC. However, there appears to be an as-yet-unknown genetic link: IC is more likely to affect both members of identical twin pairs than fraternal twin pairs. Additionally, IC tends to run in families: if one of your first-degree female relatives (i.e., your mother, sister, or daughter) has IC, your chance of also having IC is seventeen times higher than average.

Neurologic Origin

All conditions involving chronic pain are complex, and IC is no exception. Current research points to the importance of the nervous system as a key driver of chronic pain, but there is still much work to be done in this arena.

The major structures of the human body are all filled with neurons, specialized cells that help transmit messages to and from the central nervous system (the brain and spinal cord). If these neurons are irritated or malfunctioning in some way, the brain may interpret their signals as pain. Neuronal irritation can arise from infection or an injury in the region. The signaling pathways that neurons use to communicate with the central nervous system can also be disrupted, leading to the development of pain sensations.

It’s also possible that the neurons themselves may be misfiring and sending false signals to the brain and spinal cord. These aberrant signals can cause the brain to perceive pain in an area where no damage or pathologic process has occurred. (Note: in no way does this finding imply that the pain “isn’t real” - it is very real and worthy of care! To be most effective, said care should target the nervous system.)

We don’t fully understand why neurons misfire like this in people with IC. Possible triggers include prior trauma (like surgery or accidental injury), stress, and/or an overactive immune system that creates excessive, chronic inflammation. Speaking of inflammation…

Chronic Bladder Inflammation

Some people with IC have reddish lesions on the inner wall of their bladder called Hunner lesions. These lesions are associated with chronic inflammation of the bladder lining (the epithelium), and this inflammation is a potential driver of pain.

However, the absence of Hunner lesions doesn’t necessarily rule out a diagnosis of IC/PBS. While estimates of the prevalence of these lesions vary widely, it’s likely that more than half of people with IC do not have Hunner lesions. In these cases, inflammation of the bladder lining is less likely to be the source of a person’s symptoms.

Infectious Causes

Researchers have long been trying to identify an infectious agent that could cause IC, but they have yet to establish a single clear culprit. 

Different research groups have investigated bacterial, viral, and fungal infections, and all three types have been implicated as possible triggers for IC development. This suggests that there may be multiple unique pathways leading to the development of IC.

The inability to identify a clear infectious cause of IC led an international panel of experts to conclude that it should only be diagnosed when a person presents with symptoms in the absence of an identifiable infection.

Interestingly, some have suggested that recurrent UTIs could cause the nerves in the bladder to become hypersensitive. This hypersensitization could theoretically lead to chronic pain even after the infections have   have cleared. Currently, there is very little research to confirm or deny this hypothesis, and some experts in the field find it implausible.

How do healthcare providers distinguish between IC and a UTI?

As we’ve discussed, medical providers are required to rule out other potential causes of symptoms before considering a diagnosis of IC. The symptoms of IC and a UTI overlap considerably, so providers will typically test for UTIs early in the diagnostic process.

Unfortunately, standard medical testing for UTIs is innately flawed. Standard urine cultures are biased to test primarily for a single bacterial species (E. coli), and they struggle to identify other potential infectious strains. In people with UTI symptoms, standard cultures may still miss up to 50% of all known pathogens (i.e., infectious agents) that can infect the urinary tract.

To further complicate this process, 20% of women with UTI symptoms will test negative for infection by standard urine culture. The limitations of standard medical testing for UTIs make it entirely plausible that some people with diagnosed IC currently have or previously had an undiagnosed UTI.

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How is IC treated?

As with many other chronic pain conditions, there are a variety of options for treating IC, but none have been proven 100% effective. Given that IC may have different causes in different people, it’s perhaps unsurprising that the same treatment won’t work well for everyone. Many people with IC experiment with a variety of treatments to determine which work best for them.

Lifestyle factors play an important role in the management of IC: for many people, certain foods, beverages, and/or activities can trigger a symptom flare, so avoiding these triggers can help minimize symptoms.

Pelvic physical therapy can be a helpful tool if you live with IC. A Specialized pelvic PT can teach you strategies to manage symptoms, decrease the sensitivity of nerves in and around the pelvis, and reduce excessive muscle tension (which can cause pain) in the pelvic muscles.

Some people with IC benefit from medications that can be taken orally or instilled directly into the bladder through a catheter. In rare cases, a surgeon can implant a nerve stimulating device near the pelvis to improve bladder emptying and reduce pain.

If you have IC, it’s important to discuss all treatment options with your healthcare team to determine the best fit for you. A urogynecologist who specializes in treating people with IC and bladder pain can be a valuable addition to your care team.

Is there a relationship between IC and the vaginal microbiome?

It wouldn’t be an #AskEvvy article if we didn’t raise the question: how might the vaginal microbiome impact IC? Because IC is still poorly understood–and like many women’s health conditions, under-researched–we can’t yet say how or if the vaginal microbiome may be connected to it. 

Interestingly, recent research demonstrates that many urinary pathogens live inside the vagina before infecting the bladder. It’s therefore possible that the vaginal microbiome may be acting as a “reservoir” for pathogens that cause urinary infections. If researchers eventually prove that recurrent infections can cause IC, it may be worth further investigating this link.

The bladder/urinary tract itself has its own unique microbiome, just like the vagina and the gut. Like its neighboring microbiomes, the urinary microbiome varies between individuals and plays a role in both health and disease.

The urinary and vaginal microbiomes are “microbially linked”: a strain of bacteria living in your vagina can also live in your urinary tract, and vice versa. As a result, changes in your vaginal microbiome may affect your bladder: it’s possible (though still unproven) that a protective vaginal microbiome may also protect your bladder microbiome and prevent bladder-related symptoms.

At Evvy, we’re constantly working to untangle these complex relationships with the end goal of helping everyone with a vagina live their healthiest life. If you live with IC and want to learn more about your vaginal microbiome, check out the Evvy Vaginal Health Test here!