Whole-Body Cryotherapy as a Non-Pharmacological Treatment to Reduce Chronic Pelvic Pain and Improve Quality of Life in People With Endometriosis (CHILL-Endo)

An Exploratory Clinical Trial to Determine the Impact of Whole-body Cryotherapy on Endometriosis-associated Pain

The aim of this study is to investigate whether whole-body cryotherapy (a brief exposure to very cold temperatures) can help reduce pain and improve quality of life in people living with endometriosis, and whether it may represent a safe, non-pharmacological approach to managing endometriosis-related symptoms.

Up to 30 participants with symptomatic endometriosis (chronic pelvic pain for more than six months) will be recruited over a 12-month period. Participants will attend two study visits at the hospital, approximately four weeks apart. Between these visits, participants will undergo five whole-body cryotherapy sessions, each lasting approximately 3 minutes. During cryotherapy, participants stand in a specialised chamber where the body is briefly exposed to cold, dry air (around -120°C).

During the study, will be assessed changes in systemic inflammation and biological markers using blood, saliva, urine, vaginal, and stool samples. Data will be collected using questionnaires evaluating pain and related symptoms, quality of life, sleep, fatigue, intestinal symptoms, and overall wellbeing.

The active study phase lasts approximately 4-6 weeks. A final follow-up assessment at 15 weeks will be conducted remotely using questionnaires and self-collected samples.

Study Overview

• Status: Recruiting
• Conditions: Endometriosis
• Intervention / Treatment: Procedure: Whole-Body Cryotherapy

Detailed Description

Endometriosis is a chronic inflammatory and estrogen-dependent condition characterized by the presence of endometrial-like tissue outside the uterus, commonly associated with persistent pelvic pain, reduced quality of life, and significant long-term morbidity. Despite available hormonal and surgical treatments, a substantial proportion of individuals continue to experience chronic pain, highlighting an unmet need for novel therapeutic approaches. Current treatment strategies do not fully address the underlying inflammatory, neurovascular, and nociceptive mechanisms that contribute to pain persistence and central sensitization in endometriosis.

Whole-body cryotherapy (WBCT) is a non-pharmacological intervention involving brief exposure to extremely low temperatures, which has been associated with anti-inflammatory, analgesic, and neuromodulatory effects in other chronic conditions. Proposed mechanisms include modulation of systemic inflammatory pathways, reduction of oxidative stress, and effects on central pain processing. However, the potential role of WBC in the management of endometriosis-associated pain has not yet been established.

This study is a single-site, single-arm interventional pilot study designed to evaluate the feasibility, safety, acceptability, and preliminary efficacy of a structured WBCT intervention in individuals with symptomatic endometriosis. In addition to clinical outcomes, the study aims to explore biological mechanisms underlying potential treatment effects through the assessment of systemic inflammatory and other biomarkers.

Participants will undergo a standardized course of WBCT sessions over a two-week period, with repeated clinical and biological assessments conducted at predefined timepoints. Clinical outcomes will include patient-reported measures of pain, quality of life, fatigue, sleep, and other symptom domains, as well as analgesic use and global impression of change. Feasibility outcomes will include recruitment rates, retention, and participant acceptability of the intervention and study procedures.

Biological assessments will include the collection of blood (venous and capillary), saliva, urine, vaginal, and stool samples to evaluate markers of systemic inflammation, stress, and gut health. Samples will be collected at baseline, during the intervention period, and at follow-up, enabling exploration of temporal changes associated with WBC exposure.

Study visits will be conducted at baseline and post-intervention, with an additional remote follow-up evaluation. The intervention phase includes multiple WBC sessions delivered at a dedicated facility, with complementary data collection performed both in-clinic and through self-collected samples.

The findings from this exploratory study will provide preliminary evidence on the clinical and biological effects of WBCT in endometriosis, inform the feasibility of larger controlled trials, and contribute to understanding whether WBCT may represent a novel non-pharmacological approach targeting inflammatory and nociceptive pathways in endometriosis-associated pain.

• Study Type: Interventional
• Enrollment (Estimated): 30
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • Scotland
    • Edinburgh, Scotland, United Kingdom, EH16 4UX
      • Recruiting
      • Institute for Regeneration and Repair, University of Edinburgh and Royal Infirmary of Edinburgh
      • Contact: Lucy Whitaker; Phone Number: 03116518321; Email: ETMT@ed.ac.uk

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Women or assigned female at birth
• Aged 16 or over
• Endometriosis identified at laparoscopy or imaging, performed within the last ten years
• Chronic pelvic pain for more than six months
• Willing to comply with the treatment
• Willing to use effective contraception throughout the trial (if needed)
• Willing and able to give informed consent

Exclusion Criteria:

• Pregnant, breastfeeding or actively trying to get pregnant
• Post-menopausal (no periods for >12 months and not taking hormonal treatments to prevent periods, or bilateral oophorectomy performed)
• Previous hysterectomy with bilateral oophorectomy
• Raynaud's Disease
• Current treatment for malignancy
• Diabetes
• Known hypothyroidism
• Pre-existing or current diagnosis of anaemia
• Cardiovascular disease: severe hypertension (180/100, unstable angina, arrhythmia, recent (<6months) myocardial infarction, peripheral artery disease, cardiac pacemaker, recent (<6months) stroke or transient ischaemic attack)
• Acute kidney and urinary tract diseases
• Cryoglobulinemia
• Previous venous thromboembolism or peripheral artery occlusive disease
• Cold urticaria
• Livedo reticularis
• Open wounds or ulcers, large-area bacterial and viral skin infections
• Uncontrolled seizure disorder
• Known coagulopathy (eg von Willibrand disease, haemophilia)
• Severe claustrophobia
• Acute infections and fever
• Intoxication (alcohol, drugs)
• Signs or symptoms of cold allergy
• Severe wasting diseases
• Known Hepatitis B/C and/or HIV (due to Royal Mail restrictions on biospecimen postage)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Whole-Body Cryotherapy in Endometriosis; Participants with symptomatic endometriosis will undergo a structured course of whole-body cryotherapy consisting of five sessions over approximately two weeks. Each session involves brief exposure (approximately 3 minutes) to extremely cold, dry air (around -120°C) in a specialised cryotherapy chamber. Clinical and biological assessments will be conducted before and after the intervention period.

Procedure: Whole-Body Cryotherapy; Whole-body cryotherapy is a non-pharmacological intervention involving brief exposure of the body to extremely cold, dry air (typically around -110°C to -140°C) in a specialised cryotherapy chamber. Each session lasts approximately 2-3 minutes and is conducted under controlled conditions. The intervention is designed to induce physiological responses including vasoconstriction, modulation of inflammatory pathways, and potential analgesic effects.; Other Names: WBCT

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in average pain over the preceding week measured by an 11-point Numerical Rating Scale (NRS)	The Numerical Rating Scale (NRS) ranges from 0 to 10, where 0 indicates no pain and 10 indicates the worst possible pain. Participants will rate their average pain over the preceding week at baseline and at 4 weeks following completion of the cryotherapy intervention.	From baseline to 4 weeks post-intervention

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in average pain over the preceding week measured by an 11-point Numerical Rating Scale (NRS)	The Numerical Rating Scale (NRS) ranges from 0 to 10, where 0 indicates no pain and 10 indicates the worst possible pain. Participants will rate their average pain over the preceding week at baseline and at 15 weeks.	From baseline to 15 weeks
Change in neuropathic pain assessed by the PainDETECT questionnaire (PD-Q)	The PainDETECT questionnaire (PD-Q) is a validated 9-item screening tool used to assess neuropathic pain components. Scores range from -1 to 38, with higher scores indicating a higher likelihood of neuropathic pain.	From baseline to 4 weeks and 15 weeks
Change in quality of life assessed by Endometriosis Health Profile (EHP-30)	The Endometriosis Health Profile (EHP-30) questionnaire is a validated tool used to assess quality of life components over the previous four weeks. It includes 30 core questions (five scales: pain, control, emotions, social support, self-image) scoring 0-100, where higher scores indicate worse health.	From baseline to 4 weeks and 15 weeks
Change in health-related quality of life assessed by EQ-5D-5L questionnaire	The EQ-5D-5L questionnaire is a validated 5-level tool used to measure health-related quality of life, consisting of a descriptive system covering five dimensions (mobility, self-care, usual activities, pain/discomfort, anxiety/depression) and a vertical visual analogue scale (VAS) ranging from 0 (worst) to 100 (best).	From baseline to 4 weeks and 15 weeks
Change in severity of fibromyalgia symptoms assessed by Fibromyalgia Impact questionnaire	The Fibromyalgia Impact questionnaire is a validated tool used that measure the severity of fibromyalgia, its impact on daily life, and treatment progress. Scores range from 0 to 100, where higher scores indicate greater impairment. A score of 50 indicates an average patient, while over 70 indicates severe impairment.	From baseline to 4 weeks and 15 weeks
Change in fatigue assessed by the Fatigue Severity Scale (FSS)	The Fatigue Severity Scale (FSS) questionnaire is a 9-item self-report questionnaire designed to measure the severity of fatigue and its impact on daily functioning, particularly for chronic conditions. Respondents rate statements on a 7-point Likert scale (9-63), with higher scores (up to 63) indicating greater fatigue severity.	From baseline to 4 weeks and 15 weeks
Change in sleep quality assessed by the Sleep Timing Questionnaire (STQ)	The Sleep Timing Questionnaire (STQ) is a 18-item, self-report tool used to measure habitual bedtimes, wake times, sleep latency, and wake after sleep onset (like a sleep diary).	From baseline to 4 weeks and 15 weeks
Change in analgesic use during the study period	Participant-reported frequency and quantity of analgesic use.	From baseline to 4 weeks and 15 weeks
Feasibility assessed by recruitment and retention rates	Proportion of eligible participants enrolled and completing study follow-up	Frome baseline to study end. Up to 12 months
Patient satisfaction assessed by Patient Global Impression of Change (PGIC) questionnaire	The Patient Global Impression of Change (PGIC) is a 7-point, self-reported scale used in clinical practice to evaluate a patient's overall perception of improvement following the intervention. Patients select one of the following to describe their change: Very Much Improved; Much Improved; Minimally Improved; No Change; Minimally Worse; Much Worse; Very Much Worse	At 4 weeks and 15 weeks
Acceptability of the intervention assessed by a study-specific questionnaire	Overall acceptability will also be evaluated using a study-specific questionnaire assessing participant satisfaction (e.g. perceived effectiveness, and self-efficacy) with the intervention and study procedures.	At 4 weeks and 15 weeks
Change in cognitive symptoms (brain fog) assessed by the Brain Fog Scale (BFS)	The Brain Fog Scale (BFS) is a validated, self-report questionnaire designed to measure the severity of "brain fog" (cognitive difficulties such as memory impairment, lack of focus, and mental confusion and fatigue). It consists of 9 items rated on a 7-point Likert scale, with higher scores indicating greater symptom severity.	From baseline to 4 weeks and 15 weeks
Change in gastrointestinal symptoms assessed by the Irritable Bowel Syndrome Symptom Severity Score (IBS-SSS)	The IBS Symptom Severity Scale (IBS-SSS) is a 5-item, 500-point questionnaire used to measure the intensity of Irritable Bowel Syndrome symptoms over the past 10 days. It evaluates pain severity/frequency, bloating, bowel habit dissatisfaction, and quality of life, categorizing IBS as "no symptoms" (<75), "mild" (75-174), "moderate" (175-299), or severe (300-500).	From baseline to 4 weeks and 15 weeks
Change in systemic inflammatory markers with cortisol concentration	Includes serum and salivary cortisol measured in blood and saliva samples, reported in µg/dL (or nmol/L)	From baseline to 4 weeks after cryotherapy sessions and 15 weeks
Change in salivary alpha-amylase activity	Includes salivary alpha-amylase measured in saliva samples, reported in U/mL	From baseline to 4 weeks after cryotherapy sessions and 15 weeks
Change in systemic inflammatory markers with C-reactive protein (CRP) concentration	Includes serum C-reactive protein (CRP) levels in blood samples, reported in mg/L.	From baseline to 4 weeks after cryotherapy sessions and 15 weeks
Change in systemic inflammatory markers with inflammatory cytokine concentrations	Includes inflammatory cytokines (e.g., IL-6, TNF-α, IL-1β) measured in serum/plasma samples, reported in pg/mL.	From baseline to 4 weeks after cryotherapy sessions and 15 weeks
Change in bowel inflammatory markers with faecal calprotectin concentration	Includes faecal calprotectin measured in stool samples, reported in µg/g.	From baseline to 4 weeks after cryotherapy sessions and 15 weeks
Change in gut microbiome composition	Includes gut microbiome composition assessed in stool samples.	From baseline to 4 weeks after cryotherapy sessions and 15 weeks

Collaborators and Investigators

• Sponsor: University of Edinburgh
• Collaborators: NHS Lothian

Study record dates

Study Major Dates

• Study Start (Actual): April 9, 2026
• Primary Completion (Estimated): November 1, 2026
• Study Completion (Estimated): May 31, 2027

Study Registration Dates

• First Submitted: May 5, 2026
• First Submitted That Met QC Criteria: May 15, 2026
• First Posted (Actual): May 22, 2026

Study Record Updates

• Last Update Posted (Actual): May 22, 2026
• Last Update Submitted That Met QC Criteria: May 15, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: pain; cryotherapy; inflammation; endometriosis; chronic pelvic pain; endometriosis-associated pain
• Additional Relevant MeSH Terms: Urogenital Diseases; Genital Diseases; Neurologic Manifestations; Pathologic Processes; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Genital Diseases, Female; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Pain; Inflammation; Endometriosis
• Other Study ID Numbers: AC25234; 366671 (Other Identifier: IRAS Project ID (UK Health Research Authority))

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED
• IPD Plan Description: Requests for anonymised data sharing will be considered on a case by case basis by the trial management team with appropriate data sharing contracts in place.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No