Chronic pelvic pain remains a major challenge in gynecology, with unclear causes even after extensive testing, leading to empirical treatment and frustration for patients and physicians. Cannabis is under investigation as a potential treatment option; however, experts stress that its outcomes depend on the quality of care, therapeutic relationships, and multidisciplinary management.

“Patients began asking about cannabis before evidence was available, which prompted us to investigate,” said Omero Benedicto Poli-Neto, MD, PhD, associate professor at Ribeirão Preto Medical School, University of São Paulo, and clinical advisor at Hospital das Clínicas, São Paulo, Brazil, who led a Brazilian investigation into chronic pelvic pain.

Historical Context

Studies have estimated that chronic pelvic pain affects approximately 15% of women, affecting their productivity, family life, and mental health. It may present with or without evident anatomical pathology.

Identifying the mechanisms underlying pain is critical for effective treatment planning. Nociceptive, neuropathic, and nociplastic pain may overlap. Nociplastic pain, which is predominant in many cases, reflects central sensitization without detectable tissue injury. This form often requires multimodal approaches to address the central nervous system.

The most common form of pelvic pain is menstrual cramps, which can mask complex conditions such as endometriosis or extend to pain outside the menstrual cycle. Many women normalize the symptoms and live with pain for years without seeking help, which delays diagnosis and prolongs suffering.

However, imaging and surgical procedures do not always identify the cause of pain. This leaves some patients with severe pain but no visible lesions. In such cases, pain itself should be considered as a disease linked to nervous system sensitization.

Surgery has historically been the primary treatment for this condition. In the 1980s and the 1990s, exploratory laparotomies were widely performed, often without a definitive diagnosis. However, this evidence has some important limitations.

Approximately 35% of the procedures were diagnosed postoperatively. Hysterectomy remains common, with 4%-12% of US cases performed for chronic pelvic pain — more than 200,000 procedures each year.

Although many women report immediate relief, evidence suggests that 1 in 5 procedures lacks pathologic justification. Current guidelines state that surgery, especially organ removal, should be reserved for cases that meet strict criteria and should primarily focus on conservative, evidence-based, and multidisciplinary care.

Researchers have applied standardized scales to quantify pain. “A scale adds objectivity to a subjective experience. When a patient provides a score or describes pain dimensions, clinicians can track its course, evaluate treatment response, and differentiate pain profiles,” he said. They validated the Portuguese versions of the Patient Satisfaction Questionnaire and EPHect Patient Questionnaire for women with pelvic pain, providing reliable tools for research and clinical follow-up.

Evidence

International studies have shown that up to a quarter of women with pelvic pain have tried cannabis to alleviate their symptoms. Several studies have reported improvements in pain, sleep quality, mood, and anxiety. Adverse effects, such as dry mouth and somnolence, are common.

The use of cannabis in gynecology, particularly for endometriosis and chronic pelvic pain of unknown cause, is the focus of increasing research.

Studies suggest that inhaled forms can provide rapid relief from pelvic pain, whereas oral formulations appear to be more effective for gastrointestinal symptoms and mood improvement.

Current evidence shows that existing trials are of poor quality, emphasizing the need for rigorous randomized clinical trials.

In a 2022 study, Poli-Neto and colleagues examined the potential role of cannabinoids in managing chronic pelvic pain, highlighting their benefits in cases where conventional treatments are insufficient.

The authors summarized the effects of cannabinoids in endometriosis, including modulation of the endocannabinoid system and interactions with CB1 and CB2 receptors, as well as the opioid, vanilloid, and serotonergic pathways.

They highlighted the differences between tetrahydrocannabinol (THC) and cannabidiol (CBD), noting that CBD has a better safety profile than THC, which may result in neuropsychiatric adverse effects.

The authors highlighted the wide variation in formulations, doses, and routes of administration in real-world practice, calling for controlled clinical trials with standardized outcomes before routine use of this treatment.

In Brazil, products containing less than 0.2% THC are approved only for refractory epilepsy, and their use for pain is off-label. Experts caution against early adoption because of the limited evidence regarding their safety and effectiveness.

The key takeaway was the methodological caution. While the observed clinical effects are plausible, it is essential to distinguish the specific pharmacologic benefits from the contextual factors and determine which patients benefit from using which product, dose, route, and duration.

“The future is multimodal and personalized. Cannabis can be part of this puzzle, but it will not be the only piece,” emphasized Poli-Neto.

Therapeutic Effects

Poli-Neto noted that perceived benefits come not only from the substance but also from the attention and care provided by the healthcare team. This reflects well-established research on contextual effects and placebo responses in chronic pain, particularly in cannabinoid trials.

A meta-analysis of 20 randomized controlled trials using cannabinoids for pain (n = 1459) found significant pain reduction in placebo groups. The authors noted that media attention and patient expectations may amplify the response in the placebo groups.

Research shows that much of the treatment effect in pain trials comes from contextual factors, such as therapeutic rapport, expectations, empathy, clear explanations, and time spent, rather than the active ingredient alone. In practice, the physician-patient relationship measurably influences pain, function, and patient satisfaction in chronic conditions.

Observational studies have indicated that a substantial number of women with pelvic pain and endometriosis self-manage with cannabis, reporting improvements in pain, sleep, mood, and gastrointestinal symptoms. Inhaled forms generally provide rapid relief, whereas oral formulations are more effective for mood and gastrointestinal issues.

Although these findings are encouraging, they are mostly from self-reported and nonrandomized data, highlighting the need for further research.

A recent consensus acknowledged that patients with pelvic pain and other gynecologic conditions use cannabis, while highlighting methodological limitations, product variability, and the need for standardization to support safe clinical conclusions.

Poli-Neto emphasized the role of patient care in research. “The element that most drives a placebo effect is a good relationship with the patient. Establishing this relationship ensures a certain level of improvement. Listening and welcoming are therapeutic interventions in themselves,” he said.

Preliminary results from this study suggest that patients with a stronger nociplastic component may benefit more from cannabis or its derivatives. However, he cautioned that this does not apply to all individuals and that future randomized trials must account for patient heterogeneity.

In Brazil, regulatory barriers, stigma, and limited funding have hindered research progress. However, patient demands and academic interests are creating new opportunities in this field.

Poli-Neto emphasized the need to generate high-quality data adapted to the national context and promote changes in medical training. “Gynecologists are trained to operate and prescribe hormones, not to manage chronic pain as a neurobiological condition. This needs to change,” he said. “The future lies in recognizing pain as legitimate, treating it seriously, and offering women a horizon of hope,” Poli-Neto concluded.

This story was translated from Medscape’s Portuguese edition.