Low-Dose Naltrexone: The First 12-Month Trial Results

Low-Dose Naltrexone: What the First Long-Term Trial Actually Found

Low-dose naltrexone (LDN) has been widely discussed in fibromyalgia patient communities as an off-label option. The INNOVA study, published in the European Journal of Pain (2026), is the first 12-month, randomized, placebo-controlled trial to test it rigorously — and the results are important to know.

The Trial

Researchers at Parc Sanitari Sant Joan de Déu (Spain) followed 98 women with fibromyalgia for 12 months, randomly assigning them to LDN 4.5 mg/day or a matching placebo, added on top of usual care.

The Result: No Meaningful Benefit

At 3, 6, and 12 months, there was no statistically or clinically significant difference between LDN and placebo in pain intensity, function, anxiety, depression, or disability scores. Response rates were low and similar in both groups.

Safety Was Not the Issue

LDN was well tolerated, with mild, transient side effects at rates similar to placebo, and no serious treatment-related adverse events. This trial confirms LDN is safe — it simply did not outperform placebo.

Why This Matters

This result lines up with other recent trials that also failed to show a clear benefit from LDN alone. The authors are clear: this does not support routine use of 4.5 mg LDN as a stand-alone fibromyalgia treatment. That doesn't mean no one benefits — some patients may still experience relief — but the evidence doesn't support it as a general recommendation.