The restless legs guideline that put iron first and demoted the dopamine drugs

The American Academy of Sleep Medicine's clinical practice guideline for restless legs syndrome now puts iron and the gabapentinoids at the front of treatment and recommends against the routine use of the dopamine drugs — pramipexole, ropinirole, rotigotine and levodopa — that were first-line for two decades [s1]. That reversal, not any single new drug, is the story: the class most patients were started on is now the class the guideline steers clinicians away from [s1].

What the guideline says

The AASM task force graded each option using the GRADE method and assigned every recommendation a strength [s1]. The strong recommendations in adults are for gabapentin enacarbil, gabapentin and pregabalin — each "strong" with moderate certainty of evidence — and for intravenous ferric carboxymaltose in patients with appropriate iron status, also "strong" with moderate certainty [s1].

Iron is framed as foundational rather than optional. A good-practice statement instructs clinicians to test serum iron studies — including ferritin and transferrin saturation — in all patients with clinically significant RLS, ideally in the morning after avoiding iron-containing supplements and foods for at least 24 hours [s1]. The consensus supplementation thresholds it cites are notably more aggressive than for the general population: oral or IV iron when ferritin is 75 ng/mL or below or transferrin saturation is under 20%, and IV iron only when ferritin sits between 75 and 100 ng/mL [s1]. In children, iron is suggested for ferritin below 50 ng/mL [s1].

Why the dopamine drugs fell

For pramipexole, ropinirole and transdermal rotigotine, the guideline issues conditional recommendations against standard use, and it suggests against the standard use of levodopa [s1]. It goes furthest with cabergoline, which it recommends against with a strong recommendation and moderate certainty [s1].

The reason is augmentation — a paradoxical worsening in which symptoms start earlier in the day, spread to other body parts and intensify with long-term dopaminergic treatment. The guideline's remarks make the trade-off explicit: these drugs may still be used by patients who value short-term symptom reduction and place less weight on long-term adverse effects, "particularly augmentation" [s1]. Health Newspapers has covered the deprescribing problem this created — patients established on dopamine agonists for years are the hard cases the new hierarchy does not instantly solve.

The iron evidence, and its limits

The strong recommendation for IV iron rests on a modest base. In a multicentre, placebo-controlled trial of ferric carboxymaltose, the average decrease on the International Restless Legs Syndrome severity scale was 8.9 points (SD 8.52) with FCM versus 4.0 points (6.11) with placebo (p = 0.040), and 48.3% of iron-treated patients were "much" or "very much" improved on a global rating versus 14.3% on placebo (p = 0.004) [s2]. The authors themselves called it a "preliminary" trial and said larger studies were needed [s2].

That is the honest shape of the evidence: the direction is consistent and the safety profile is favourable, but the individual trials are small, which is why the guideline pairs a strong recommendation with only moderate certainty [s1]. Several other iron formulations — IV low molecular weight iron dextran, IV ferumoxytol and oral ferrous sulfate — carry weaker, conditional recommendations [s1].

What it means for a reader

The practical shift is that iron studies are now a starting point rather than an afterthought, and that a patient's ferritin and transferrin saturation can determine whether treatment begins with oral iron, intravenous iron, or a gabapentinoid [s1]. The guideline also lists first steps that require no prescription at all: addressing exacerbating factors such as alcohol, caffeine, antihistamines, serotonergic and antidopaminergic medicines, and untreated obstructive sleep apnea [s1]. RLS is common in pregnancy, and the guideline tells prescribers to weigh the pregnancy-specific safety of each option [s1]. None of this is medical advice; the thresholds and choices belong to a clinician.

What to watch

Whether larger iron trials firm up the certainty behind the strong recommendation, and how quickly real-world prescribing follows a guideline that asks clinicians to unwind a class of drugs many patients have taken for years. A guideline can change first-line therapy overnight; changing what is already in a medicine cabinet is slower.

This article is informational and is not medical advice.

Sources

• Treatment of restless legs syndrome and periodic limb movement disorder: an AASM clinical practice guideline — Journal of Clinical Sleep Medicine, 2025-01-01
• Clinical efficacy and safety of IV ferric carboxymaltose (FCM) treatment of RLS — Sleep Medicine, 2011-10-11