Caffeine Demonstrates Surprising Opioid-Dependent Effect on Fibromyalgia Pain

Patients with fibromyalgia who take opioids and consume caffeine have significantly lower pain interference, pain catastrophizing, less pain severity and depressive symptoms, and higher physical function than patients taking opioids who avoid caffeine.

By Katie Estes, PhD

Interviews with Ryan Scott, MPH, CPH and Don Goldenberg, MD.

A reported 85% of American adults consume caffeine on a daily basis.¹ The psychologic and physiologic effects, including elevated mood, favorable cardiovascular effects, and increased attention have been well documented.^2-4 However, the effects of caffeine on chronic pain are not well understood.

The worldwide use of caffeine has led to many studies, including research on its role in pain mitigation. For treating acute pain, caffeine acts as an analgesic adjuvant.⁵ Indeed, many over-the-counter analgesics contain caffeine for this reason. The effects of caffeine on chronic pain are not well understood

To begin to understand the role of caffeine on chronic pain, Ryan Scott, MPH, CCRP, clinical research projector manager at the Chronic Pain & Fatigue Research Center at the University of Michigan Medical School in Ann Arbor, Michigan, examined the role of caffeine in fibromyalgia treatment.⁶

Scott and his colleagues found that among patients with fibromyalgia, those who consumed caffeine had significantly lower pain interference, pain catastrophizing, less pain severity, lower levels of depression and higher physical function than patients who did not consume caffeine.⁶ These effects appear to be dose-dependent and did not extend to patients who consumed caffeine but were not taking opioids, suggesting an opioid adjuvant effect.⁶

Findings of the study by Scott et al on the effects of caffeine in patients who were taking opioids for the chronic pain from fibromyalgia⁶ were published in the Journal of Pain Research.

Studying the Potential Analgesic Effects of Caffeine

Fibromyalgia is a chronic pain condition characterized by widespread pain, fatigue, and memory problems.⁷ Scott and colleagues hypothesized that caffeine would show an analgesic effect on pain in fibromyalgia patients, and an adjuvant effect in patients taking opioids.⁶

The researchers used patients enrolled in an ongoing research initiative at the Back and Pain Center in the University of Michigan Health System. Using the American College of Rheumatology 2011 Survey Criteria for Fibromyalgia as the criteria,⁸ some 962 patients with fibromyalgia met the criteria for inclusion in the study.

Patients were split into groups based on whether they were currently taking an opioid (568 patients, 59%) or not (394 patients, 41%).⁶ They were further stratified into 4 groups based on caffeine consumption: no caffeine, low, moderate or high caffeine intake. The amounts of caffeine consumed per day and the proportion of patients who consumed caffeine did not differ between opioid users and nonusers.⁶

The researchers used patient-reported outcomes to assess pain severity, pain interference, physical function, pain catastrophizing, depression, anxiety, positive affect and negative effect.

Caffeine consumption Associated with Reduced Severity of Symptoms

Among opioid nonusers who consumed caffeine, patients only had a significant difference in physical function over those who were not taking opioids and did not have caffeine (F = 3.23, p = 0.023).⁶

“We found it surprising that in fibromyalgia patients not taking opioids, caffeine consumption was only associated with improved physical function,” Scott told Practical Pain Management. The authors expected more of an analgesic effect from caffeine consumption in general.

Whereas fibromyalgia patients taking opioids (as opposed to nonusers) who consumed caffeine reported benefits that had a significant difference on pain interference (F = 2.77, p = 0.041), pain catastrophizing ( F = 4.16, p = 0.006), and physical function (F= 4.97, p = 0.002) as compared with opioid users who did not consume caffeine.⁶

Caffeine Impact is Dose-Dependent

Post hoc analysis also revealed a dose-dependent effect. The low caffeine opioid group had significantly lower pain interference (p= 0.028), pain catastrophizing (p=0.022), and higher physical function (p = 0.003) compared with the no caffeine opioid group.⁶

The moderate caffeine group had significantly less pain severity (p = 0.041), pain interference (p=0.033), pain catastrophizing (p=0.048) and depression (p = 0.024) and higher physical function (p = 0.001). Lastly, the high caffeine group had significantly lower pain catastrophizing (p = 0.002) and higher physical function (p = 0.015). Therefore, the moderate caffeine consumption group had the greatest benefit from caffeine.⁶

While we did not find that caffeine intake had an effect on fibromyalgia pain severity in opioid nonusers, exploratory analyses not controlling for multiple comparisons showed significantly lower pain severity and pain-related interference in caffeine consumers vs. non-consumers,⁶ according to Scott.

It may be that some of the benefit seen in opioid users may be due to caffeine counteracting or diminishing the sedative or cognitive impairment effects often seen with opioid use, said Scott.The authors caution that both of these conclusions are preliminary, and further rigorous study is needed to confirm these observations.⁶

Can caffeine help patients with chronic pain?

Don Goldenberg, MD, a rheumatologist and affiliate faculty in the Department of Medicine at the School of Nursing at Oregon Health Services University in Portland, Oregon, who was not affiliated with the study, told Practical Pain Management, “this is a well-done research study in which the results demonstrate an adjunctive pain-relieving effect for caffeine only in opioid users but not in non-opioid users.”

“This main finding has to be tempered with the current recommendation that opioids not be used in fibromyalgia or similar chronic pain disorders,” said Dr. Goldenberg, “Yet, even in this study, from a medical center that were following the guidelines, more than 50% of fibromyalgia patients were on chronic, regular opioid therapy. Therefore, the message for clinicians might be to think about recommending modest amounts of caffeine in patients who are on opioids.”

“Another interesting consideration that has not been studied is whether caffeine might even help to get patients off opioids but that could be a consideration,” Dr. Goldenberg said.

“Ideally, we hope to see a decrease in the number of chronic pain patients, particularly with pain conditions such as fibromyalgia, on opioid medications,” Mr. Scott agreed, “We hope that this study helps raise awareness of the role of caffeine in pain and the need for additional research in this area. Furthermore, that caffeine intake should be taken into consideration as part of research and clinical care, as it can influence pain and other symptoms.”

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