Pelvic pain experienced by those with IC typically worsens with filling of the urinary bladder and may improve with urination.

[22] Other suggested etiological causes are neurologic, allergic, genetic, and stress-psychological including exposure to abuse in childhood or adulthood.

[15][23][24][25] In addition, recent research shows that those with IC may have a substance in the urine that inhibits the growth of cells in the bladder epithelium.

Evidence from clinical and laboratory studies confirms that mast cells play a central role in IC/BPS possibly due to their ability to release histamine and cause pain, swelling, scarring, and interfere with healing.

[27] When the surface glycosaminoglycan (GAG) layer is damaged (via a urinary tract infection (UTI), traumatic injury, etc.

[29] Deficiency in this glycosaminoglycan layer on the surface of the bladder results in increased permeability of the underlying submucosal tissues.

An unknown toxin or stimuli may activate nerves within the bladder wall, causing the release of neuropeptides.

[10] The American Urological Association Guidelines recommend starting with a careful history of the person, physical examination and laboratory tests to assess and document symptoms of interstitial cytitis,[33] as well as other potential disorders.

In 2006, the ESSIC society proposed more rigorous and demanding diagnostic methods with specific classification criteria so that it cannot be confused with other, similar conditions.

Secondly, they strongly encourage the exclusion of confusable diseases through an extensive and expensive series of tests including (A) a medical history and physical exam, (B) a dipstick urinalysis, various urine cultures, and a serum PSA in men over 40, (C) flowmetry and post-void residual urine volume by ultrasound scanning and (D) cystoscopy.

[38] IC/BPS is commonly misdiagnosed as chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) in men,[39] and endometriosis and uterine fibroids (in women).

[8][7] They include treatments ranging from conservative to more invasive: The American Urological Association guidelines also listed several discontinued treatments, including long-term oral antibiotics, intravesical bacillus Calmette Guerin, intravesical resiniferatoxin), high-pressure and long-duration hydrodistention, and systemic glucocorticoids.

The proportion of people with IC/BPS who experience relief from hydrodistention is currently unknown and evidence for this modality is limited by a lack of properly controlled studies.

[10] Bladder instillation of medication is one of the main forms of treatment of interstitial cystitis, but evidence for its effectiveness is currently limited.

[10][13] Other agents used for bladder instillations to treat interstitial cystitis include: heparin, lidocaine, chondroitin sulfate, hyaluronic acid, pentosan polysulfate, oxybutynin, and botulinum toxin A.

Preliminary evidence suggests these agents are efficacious in reducing symptoms of interstitial cystitis, but further study with larger, randomized, controlled clinical trials is needed.

[44] The foundation of therapy is a modification of diet to help people avoid those foods which can further irritate the damaged bladder wall.

[46] Nonsteroidal anti-inflammatory drug and paracetamol and gastric protection combined with other conservative measures can be an effect first-line treatment.

[7] As a second-line treatment, amitriptyline has been shown to be effective in reducing symptoms such as chronic pelvic pain and nocturia[10] in many people with IC/BPS with a median dose of 75 mg daily.

[13] Oral pentosan polysulfate is believed to repair the protective glycosaminoglycan coating of the bladder, but studies have encountered mixed results when attempting to determine if the effect is statistically significant compared to placebo.

[10][47][28] The antihistamine hydroxyzine failed to demonstrate superiority over placebo in treatment of people with IC in a randomized, controlled, clinical trial.

[49] This may leave the pelvic area in a sensitized condition, resulting in a loop of muscle tension and heightened neurological feedback (neural wind-up), a form of myofascial pain syndrome.

Current protocols, such as the Wise–Anderson Protocol, largely focus on stretches to release overtensed muscles in the pelvic or anal area (commonly referred to as trigger points), physical therapy to the area, and progressive relaxation therapy to reduce causative stress.

A specially trained physical therapist can provide direct, hands on evaluation of the muscles, both externally and internally.

Surgical intervention is very unpredictable, and is considered a treatment of last resort for severe refractory cases of interstitial cystitis.

[55] Percutaneous sacral nerve root stimulation was able to produce statistically significant improvements in several parameters, including pain.

[57] Despite a scarcity of controlled studies on alternative medicine and IC/BPS, "rather good results have been obtained" when acupuncture is combined with other treatments.

[10] A 2012 survey showed that among a group of adult women with symptoms of interstitial cystitis, 11% reported suicidal thoughts in the past two weeks.

[69][70] Philadelphia surgeon Joseph Parrish published the earliest record of interstitial cystitis in 1836 describing three cases of severe lower urinary tract symptoms without the presence of a bladder stone.

Recently, the European Society for the study of Interstitial Cystitis (ESSIC) proposed the moniker, 'bladder pain syndrome' (BPS) [van de Merwe et al.