Sublingual Cyclobenzaprine for Fibromyalgia: A Win, But a Modest One Save

It is encouraging to see a new treatment option for fibromyalgia after more than 15 years without a new FDA-approved therapy. But we should look beyond whether a trial met its statistical endpoint and ask a more practical question: how much better did patients actually feel?

At ACR Convergence 2026, Abstract #2546 looked across four randomized, placebo-controlled trials of bedtime sublingual cyclobenzaprine. BESTFIT and AFFIRM studied 2.8 mg, with 103 and 262 actively treated patients, while RELIEF and RESILIENT included 248 and 231 patients treated with the 5.6-mg regimen.

Pain scores fell by approximately 1.4 points in both 2.8-mg studies, compared with 1.91 points in RELIEF and 1.82 points in RESILIENT with 5.6 mg. The authors therefore suggest that 5.6 mg provides more consistent efficacy without compromising tolerability.

There are important caveats. This was not a head-to-head dose comparison. The trials were conducted separately, and the earlier 2.8-mg studies were analyzed post hoc to align with the later pivotal trials. The results therefore suggest, but do not prove, a dose-response relationship.

More importantly, the benefit over placebo was modest. In RELIEF, pain decreased 1.9 points with sublingual cyclobenzaprine versus 1.5 points with placebo, a difference of only about 0.4 points on a 0–10 scale, despite meeting the primary endpoint (P=0.01). The substantial placebo response is important in fibromyalgia trials because improvement in both groups can narrow the treatment-placebo difference

That does not mean the treatment lacks value. RELIEF also showed improvements in fibromyalgia impact, sleep disturbance, fatigue, and sleep quality, suggesting that pain scores alone may not capture the entire clinical benefit.

My take: I welcome sublingual cyclobenzaprine as another option for fibromyalgia, but I see it as an incremental rather than transformative advance. Abstract #2546 shows how the development program progressed from an inconsistent signal at 2.8 mg to reproducible efficacy with 5.6 mg. But reproducibility is not the same as a large treatment effect.

For some patients, particularly those with prominent nonrestorative sleep, the benefit may be meaningful. The real-world question is not simply whether sublingual cyclobenzaprine works, but who responds, how much better they feel, and whether improvements in sleep, fatigue, pain, and function are enough to continue treatment.