What is the best painkiller for chronic pelvic floor spasms

The short version: there is no single best painkiller for chronic pelvic floor spasms, and the evidence points away from drugs as the primary answer.

The evidence you were given does not test one painkiller against another for this condition. What it does show is that non-drug approaches consistently outperform medications in the studies that exist. A randomized trial of pelvic floor relaxation with biofeedback and electrical stimulation produced a drop in pain scores from 15.2 to 2.7, and the improvement held at 6 months [11]. Conventional therapy (alpha-blockers, anti-inflammatories) in the same trial dropped pain from 15.3 to 4.2 at 3 months, but by 6 months the scores had returned to baseline [11]. That is a drug-based approach that does not last.

Thiele massage, a specific internal manual therapy, took pain scores from 8.1 to 1.5 on a 10-point scale in one study [4]. Botulinum toxin injections into the pelvic floor muscles reduced pain by about 43% in a retrospective series and by 90% in a single case report [5]. A pilot study of vaginal electrostimulation guided by EMG mapping found that 93% of patients reported pain relief at follow-up [8]. None of these are pills, and all of them target the muscle directly rather than numbing the nervous system.

The drugs that get prescribed most often for this condition are gabapentin, pregabalin, amitriptyline, and opioids [1]. The evidence for them is weak. The one trial that combined gabapentin with amitriptyline for chronic pelvic pain was not blinded and had only 56 women [24]. Opioids carry addiction risk and do not fix the underlying spasm. Pregabalin and gabapentin can cause dizziness, sedation, and weight gain, and their effect on pelvic floor spasm specifically has never been tested in a proper trial.

My call: the best approach is physical therapy with biofeedback or manual therapy, not a pill. If you need something for breakthrough pain, a short course of a muscle relaxant like baclofen or tizanidine is more targeted than gabapentin, but the evidence for those is also thin [1]. Confidence: moderate. The non-drug studies are small but consistent. The drug studies for this condition are almost nonexistent.