Restless legs syndrome: iron, gabapentinoids, and avoiding augmentation

Restless legs syndrome (RLS) — also called Willis-Ekbom disease — is a sensorimotor neurological condition affecting 5–10% of Australian adults. It is one of the most common causes of chronic insomnia and is significantly underdiagnosed. Despite its straightforward clinical criteria, it is frequently mistaken for nocturnal cramps, peripheral neuropathy, or anxiety. Correct identification matters, because treatment is specific and effective when targeted correctly.

The most important development in recent years is the 2024 AASM clinical practice guideline update, which reclassifies gabapentinoids as first-line pharmacotherapy and formally downgrades dopamine agonists — reversing the treatment landscape that most clinicians were trained on.

A. Core clinical — the AU general-practice framework

The five diagnostic criteria (IRLSSG 2014)

Diagnosis of RLS is clinical, requiring all five IRLSSG 2014 criteria to be met:

1. Urge to move the legs — usually accompanied by, or caused by, uncomfortable and unpleasant sensations (crawling, creeping, pulling, itching, burning, or aching — but sometimes just pure urge without pain)
2. Onset or worsening at rest — sitting or lying down; symptoms begin or worsen during periods of inactivity
3. Relief with movement — walking, stretching, or pacing at least partially relieves symptoms as long as movement continues
4. Worse in the evening or night — exclusively or predominantly so; circadian pattern is a defining feature
5. Not fully explained by another condition — the symptoms are not solely explained by leg cramps, positional discomfort, leg oedema, arthritis, peripheral neuropathy, varicose veins, or akathisia

Additional supportive features include a positive family history (50% of primary RLS is familial), periodic limb movements during sleep (PLMS index ≥15/hour on polysomnography), and a history of response to dopaminergic therapy.

Differential diagnosis

Mimic	How to distinguish
Nocturnal leg cramps	Sudden, painful, palpable muscle contraction; no urge-to-move quality; relieved by stretching, not sustained movement
Peripheral neuropathy	Continuous stocking-distribution symptoms; not predominantly nocturnal; reduced reflexes; nerve conduction study abnormal
Akathisia (drug-induced)	Whole-body restlessness; linked to antipsychotic, metoclopramide, or SSRI use; not specifically circadian or rest-related
Positional discomfort / varicose veins	Visible signs; relieved by elevation, not walking
Anxiety and generalised restlessness	Not specifically nocturnal; not specifically rest-related; not relieved by leg movement

Causes and secondary contributors

Type	Notes
Primary / idiopathic	Familial in about 50%; usually earlier onset; genetically linked (BTBD9, MEIS1 GWAS variants)
Iron deficiency	Most common reversible cause; normal-range ferritin (below 75–100 μg/L) may be insufficient
Pregnancy	Common, especially third trimester; usually resolves postpartum; iron deficiency is the main driver
Chronic kidney disease (especially dialysis)	High prevalence; treat iron deficiency first, then gabapentinoid or low-dose dopamine agonist
Peripheral neuropathy	Diabetic, alcohol-related, or paraproteinaemic
Medication-induced	SSRIs, SNRIs, mirtazapine, TCAs, first-generation antihistamines, dopamine antagonists (metoclopramide, antipsychotics), some beta-blockers
Other secondary	Hypothyroidism, B12 deficiency, magnesium deficiency, spinal cord disease

Investigations

Test	Rationale
Ferritin and iron studies (Fe, transferrin saturation, TIBC)	Ferritin target >100 μg/L for RLS; TSAT <20% indicates functional iron deficiency even with normal ferritin
Full blood count	Detect accompanying anaemia; assess haematological severity
U&E and eGFR	CKD-associated RLS
TSH	Hypothyroidism as secondary cause
Vitamin B12 and folate	Deficiency contributes and is correctable
Magnesium	Deficiency may contribute
Fasting glucose or HbA1c	Diabetic neuropathy as secondary driver
Pregnancy test	If clinically appropriate
Polysomnography	Not routine; reserved for diagnostic uncertainty, suspected OSA, or suspected PLMD as the primary diagnosis

Severity and impact

IRLS Rating Scale (10 items, scored 0–40) quantifies severity. Clinical classification:

• Occasional (fewer than 2 episodes per week) — lifestyle approach; iron if deficient
• Frequent (2–3 episodes per week) — pharmacotherapy warrantable
• Severe (4 or more episodes per week) — medication usually required alongside iron and lifestyle

B. Treatment — step-by-step

Step 1 — treat iron deficiency

Iron deficiency is present or contributing in the majority of secondary RLS cases and is the most important reversible cause. The IRLSSG and 2024 AASM guideline recommend targeting ferritin above 100 μg/L and transferrin saturation above 20%.

Oral iron — ferrous sulfate 325 mg, ferrous fumarate 200 mg, or ferrous gluconate 300 mg. Alternate-day dosing (every other day) maximises absorption by preventing hepcidin upregulation. Take with ascorbic acid (vitamin C) to enhance absorption; avoid with tea, coffee, calcium, or antacids. Re-check ferritin and iron studies 4–6 weeks after starting.

Intravenous iron — ferric carboxymaltose (Ferinject) or iron polymaltose (Ferrosig) — produces faster and more pronounced symptom improvement than oral iron, particularly in severe deficiency or poor oral tolerance. PBS Authority Required for documented iron deficiency with clinical indication. IV iron often markedly reduces or resolves RLS symptoms without any need for pharmacotherapy.

The Cochrane 2019 review (Trotti and Becker) confirms that iron supplementation reduces RLS symptoms when deficiency is present or suspected.

Step 2 — lifestyle measures and medication review

Review the medication list for RLS-exacerbating agents and substitute where possible: replace metoclopramide with ondansetron for nausea; consider bupropion instead of SSRIs for depression if RLS is worsening. Advise: avoid caffeine, alcohol, and nicotine in the afternoon and evening; establish regular moderate exercise (aerobic and resistance); apply warm or cool packs to the legs; use distraction during symptomatic periods.

Step 3 — gabapentinoids (first-line pharmacotherapy per AASM 2024)

The 2024 AASM clinical practice guideline explicitly recommends gabapentinoids as first-line pharmacotherapy for RLS — a significant departure from previous guidance that favoured dopamine agonists.

Gabapentin — start at 300 mg at night; titrate by 300 mg every week to effect; effective doses typically 900–1,800 mg nightly. Dose-adjust for renal impairment. PBS Authority Required under neuropathic pain or anxiety indications (RLS is not an explicit PBS indication for gabapentin; prescribers document as neuropathic pain features when present, or prescribe privately). Particularly useful when neuropathic pain is co-present with RLS.

Pregabalin — start at 75 mg at night; titrate to 150–300 mg. Faster titration than gabapentin. PBS Authority Required (Streamlined) under neuropathic pain or generalised anxiety disorder indications. Monitored in some states under SafeScript (check before prescribing).

Both agents cause initial sedation and dizziness, which improves with dose titration. They carry dependence potential, particularly at higher doses, which should be discussed with patients.

Step 4 — dopamine agonists (now second-line)

Dopamine agonists remain effective short-term but are no longer first-line because of augmentation:

• Pramipexole 0.125–0.5 mg, one to three hours before bedtime — PBS general schedule for RLS. Effective acutely but associated with augmentation in 30–50% of long-term users. Also associated with impulse control disorders (gambling, hypersexuality, compulsive buying) — screen and monitor.
• Ropinirole 0.25–4 mg evening — similar profile to pramipexole; less commonly used in Australia for RLS.
• Rotigotine patch 1–3 mg/24h — lower augmentation rate than oral agents due to continuous delivery; useful in renal failure where nocturnal dosing is impractical. PBS Authority Required.
• Levodopa — historical; not recommended for chronic use due to extremely high augmentation rates; occasionally appropriate for purely intermittent RLS.

Augmentation — recognise and manage

Augmentation is the most clinically important complication of dopamine agonist therapy per the Garcia-Borreguero 2016 augmentation guideline. Features include:

• Symptoms appearing earlier in the day than before treatment
• Spread to the arms or trunk
• Increased severity at the same dose
• Shorter duration of relief after doses

Management of augmentation: optimise iron to above 100 μg/L; switch to a gabapentinoid, with gradual dopamine agonist taper (abrupt withdrawal causes rebound); consider low-dose opioid if gabapentinoid is insufficient; refer to a sleep physician or neurologist for complex augmentation.

Step 5 — refractory cases and opioids

For severe RLS refractory to iron repletion and gabapentinoids, low-dose opioids under specialist supervision:

• Oxycodone-naloxone (Targin) — low-dose evening; PBS Authority Required for chronic non-cancer pain; SafeScript monitored in most states
• Methadone 2.5–10 mg evening — specialist-supervised; SafeScript monitored
• Refer to a sleep physician or neurologist before initiating opioid therapy for RLS

C. Evidence — key trial findings

• Cochrane 2019 iron review — IV iron significantly reduces RLS severity; oral iron is less consistent but beneficial when adequately absorbed
• AASM 2024 update (Winkelman et al.) — first-line gabapentinoids; dopamine agonists relegated to second-line
• Garcia-Borreguero 2016 — augmentation in 30–50% of long-term pramipexole users; lower rate with rotigotine
• Trenkwalder 2013 — oxycodone-naloxone effective for severe, refractory RLS
• Aukerman 2006 RCT — aerobic and resistance exercise reduces RLS severity by approximately 40% compared with control

D. Australian operations

PBS and MBS

PBS access: Iron preparations (oral and IV with Authority). Pramipexole and ropinirole are general PBS schedule for RLS. Rotigotine patch is Authority Required. Gabapentin and pregabalin are Authority Required (Streamlined) for neuropathic pain or GAD — not explicitly for RLS; prescribers need to document the appropriate indication. Oxycodone-naloxone and methadone are Authority Required for chronic non-cancer pain; SafeScript checked at every prescribing event. The PBS website lists current Authority requirements and streamlined codes.

SafeScript: Pregabalin is monitored medicine in Victoria, Queensland, ACT, and others; check at every prescribing event. Opioids are monitored in all states and territories. If initiating either drug class, document indication, baseline assessment, and monitoring plan.

MBS: Standard GP consults (items 23, 36, 44). Mental Health Treatment Plan (items 2715/2717) if comorbid depression or anxiety. Polysomnography (items 12203–12217) via sleep physician referral. Sleep physician consultation (items 110/116). Telehealth consult items for follow-up.

Consumer resources and referral

• Sleep Health Foundation Australia — patient information, practitioner directory
• HealthDirect — Restless legs syndrome
• Australasian Sleep Association — clinician and patient resources

E. Special populations

Pregnancy. RLS is common (up to 25% in the third trimester) and iron deficiency is the main driver. Non-pharmacological approaches first. Oral iron is the usual initial treatment; IV iron with obstetric input if oral iron is insufficient. Most pharmacological agents have limited pregnancy safety data: gabapentinoids are generally avoided in the first trimester; dopamine agonists are not recommended; short-term low-dose clonazepam is occasionally used in the third trimester for severe cases with specialist input. RLS nearly always resolves or markedly improves after delivery.

Chronic kidney disease. RLS is very prevalent in CKD, particularly in those on dialysis. Iron deficiency is common and treatable. Gabapentinoids require significant dose reduction for eGFR below 30 mL/min/1.73m² — use renal dosing tables. Low-dose rotigotine is often well tolerated in dialysis patients. Optimising dialysis adequacy independently reduces RLS severity.

Children. RLS affects approximately 2% of children. Iron deficiency is very common. Screen and treat iron deficiency; address sleep hygiene and comorbidities. Pharmacotherapy has limited paediatric safety data — involve a paediatric sleep specialist.

Older adults. Falls risk is increased with gabapentinoids and dopamine agonists. Start at very low doses and titrate slowly. Dopamine agonist impulse control disorders may present differently in older adults; caution with pre-existing cognitive impairment. Opioids carry additional fall and sedation risk.

When to escalate

Refer to a sleep physician or neurologist when:

• Diagnosis is uncertain (e.g., cannot fully distinguish from neuropathy or akathisia)
• Refractory RLS despite iron optimisation and an adequate gabapentinoid trial
• Augmentation has developed on dopamine agonist therapy and transition to gabapentinoid is complex
• Opioid therapy is being considered for refractory RLS
• Co-existing suspected obstructive sleep apnoea or periodic limb movement disorder as a separate diagnosis
• Pregnancy with severe RLS requiring pharmacotherapy

Urgent (same-day) review is not typically required for RLS in isolation — it is a chronic condition. However, new severe insomnia with functional impairment warrants a prompt GP review to consider RLS among other causes.

What this article is and is not

This article draws on current guidelines — AASM 2024 clinical practice guideline, IRLSSG diagnostic criteria, Therapeutic Guidelines (eTG), RACGP resources, the Sleep Health Foundation Australia, and Cochrane evidence — to provide general health information about restless legs syndrome. It is not personal medical advice and does not create a doctor–patient relationship.

All decisions about medication choice, dose, and duration — including the choice between gabapentinoids, dopamine agonists, and other therapies — are made with your GP or treating clinician based on your individual circumstances, including any other medical conditions and medications you are taking.

For consumer-friendly resources: Sleep Health Foundation Australia, HealthDirect — restless legs syndrome.

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Sources cited

1. Winkelman et al. — AASM Clinical Practice Guideline for RLS and PLMD 2024 (J Clin Sleep Med)
2. Therapeutic Guidelines (eTG) — Neurology/Sleep: restless legs syndrome
3. RACGP — Sleep medicine resources
4. Sleep Health Foundation Australia
5. Trotti and Becker — Iron supplementation for RLS (Cochrane 2019)
6. Garcia-Borreguero et al. — IRLSSG guidelines on augmentation (Sleep Med 2016)
7. Allen et al. — IRLSSG diagnostic criteria (Sleep Med 2014)
8. PBS — Pramipexole, pregabalin, gabapentin listings
9. HealthDirect — Restless legs syndrome