Restless legs syndrome

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Restless legs syndrome is a sensorimotor disorder diagnosed clinically. Ask the person to describe what happens while sitting through a film or trying to sleep, what movement does and how symptoms vary across the day. The sensory description may be crawling, pulling, tingling, aching or simply an irresistible need to move. Periodic limb movements during sleep are common but neither required nor sufficient; a bed partner may report repetitive leg flexion while the patient mainly reports insomnia and daytime fatigue.

The differential is resolved by the four-part pattern and examination. Nocturnal cramp is focal, painful and associated with sustained muscle tightening. Peripheral neuropathy usually continues during activity and leaves sensory signs. Venous disease causes swelling or discomfort not immediately relieved by walking. Akathisia follows dopamine blockade or another medicine and produces generalised motor restlessness across the day. Positional discomfort resolves with a simple change rather than recurring circadian urge.

Treatment depends on frequency, distress and cause. Intermittent mild symptoms may need no drug. Iron replacement can be disease-modifying when stores are insufficient. Alpha-2-delta ligands and dopamine agonists have different adverse profiles, and opioids are reserved for refractory specialist care because of dependence and respiratory risk. Ferritin thresholds and infusion regimens depend on local laboratory ranges, kidney care, pregnancy and sleep or neurology expertise.

Key points

The diagnostic core is an urge to move the legs, usually with unpleasant sensations, beginning or worsening during rest, relieved by movement and more prominent in the evening or night.
Walking, stretching, rubbing or moving brings temporary relief; pain that persists unchanged during movement or occurs mainly on exertion suggests another cause.
Primary RLS can be familial, but iron deficiency, pregnancy, chronic kidney disease and some neurological disorders are important associated states.
Review medicines that may worsen symptoms, including dopamine-blocking antiemetics or antipsychotics, sedating antihistamines and some antidepressants, while never stopping essential treatment abruptly.
Check full blood count, ferritin and transferrin saturation because iron depletion can exist without anaemia and ferritin may be misleadingly raised by inflammation.
Nocturnal leg cramps cause a painful palpable contraction, neuropathy causes persistent burning or numbness, and akathisia creates whole-body inner restlessness without the characteristic evening sensory pattern.
Start with explanation, regular sleep, moderate daytime activity, stretching or massage, and reduction of late caffeine, nicotine and alcohol where relevant.
Replace demonstrable iron deficiency using a locally governed oral or intravenous plan, documenting the biochemical target and excluding unsafe iron loading.
Gabapentin or pregabalin may be preferred for frequent troublesome disease, especially with pain or insomnia, but sedation, dependence potential and renal dosing require care.
Dopamine agonists can cause augmentation—earlier, more intense, rapidly provoked and anatomically spreading symptoms—and impulse-control disorders, so they are not a consequence-free chronic solution.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Primary familial susceptibility

Many cases are idiopathic and familial, reflecting inherited vulnerability in sensory-motor and iron-related brain systems across affected families.

Iron deficiency

Low iron stores can provoke or worsen RLS even without anaemia, while inflammation may make ferritin alone misleading.

Pregnancy and kidney disease

Pregnancy and chronic kidney impairment alter iron, metabolic and neural physiology and are important secondary associations.

Medicine-related exacerbation

Dopamine-blocking medicines, sedating antihistamines and some antidepressants can worsen symptoms, but essential treatment should not be stopped abruptly.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Brain iron dysregulation
Reduced iron availability alters enzymes and signalling within subcortical sensory-motor networks despite sometimes normal peripheral indices.
2
Dopaminergic timing disturbance
Abnormal dopamine regulation contributes to evening-predominant rest symptoms and explains both treatment response and augmentation risk.
3
Rest-related sensory-motor drive
Inactivity permits unpleasant leg sensations and an urge to move, while walking or stretching temporarily normalises network output.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Classic urge pattern

An uncomfortable need to move both legs that starts while resting, improves promptly with walking and returns on sitting, especially at night, strongly supports RLS.

Sleep consequence

Difficulty initiating sleep, repeated waking, bed-partner reports of limb movements and daytime fatigue show disease burden even when daytime neurological examination is normal.

Iron-associated disease

Low ferritin or transferrin saturation, blood loss, poor intake or malabsorption may precipitate or worsen RLS despite a normal haemoglobin concentration.

Medication trigger

Symptoms beginning after a dopamine antagonist, sedating antihistamine or selected antidepressant, or worsening after a dose change, supports a drug contribution that should be reviewed safely.

Dopaminergic augmentationRed flag

Symptoms that start progressively earlier, appear after shorter rest, become more severe or spread from legs to arms during dopamine therapy suggest augmentation rather than simple disease progression.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Full blood count, ferritin and transferrin saturationFirst step
Why
Identify iron depletion, anaemia and a treatable contributor before symptomatic medication is escalated.
Interpretation and limitations
Low stores support replacement even when haemoglobin is normal. Ferritin rises with inflammation, so transferrin saturation and clinical context help avoid a falsely reassuring result.
02
Renal function and metabolic profile
Why
Detect chronic kidney disease and provide safe dosing information for gabapentinoids.
Interpretation and limitations
RLS is common in advanced kidney disease, while pregabalin and gabapentin accumulate as filtration falls. Electrolyte abnormalities may instead support cramp or neuropathy.
03
Medication and substance review
Why
Find exacerbating drugs, dopaminergic augmentation and sleep-disrupting caffeine, alcohol or nicotine patterns.
Interpretation and limitations
The timeline is more useful than a generic prohibited list. Balance any change against the reason for treatment and involve psychiatry or other prescribers before reducing an essential medicine.
04
Neurological and vascular examination
Why
Identify neuropathy, radiculopathy, parkinsonism, myelopathy or unilateral vascular disease that challenges primary RLS.
Interpretation and limitations
A normal examination is common in RLS. Objective weakness, sensory level, asymmetric oedema, absent pulses or persistent sensory loss requires a separate diagnostic pathway.
05
Sleep study
Why
Investigate an alternative sleep disorder or quantify limb movements when the diagnosis or treatment response remains unclear.
Interpretation and limitations
Polysomnography is not needed to diagnose a classic RLS history. Periodic limb movements can occur without RLS and should not replace the clinical criteria.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Nocturnal leg cramps

A painful palpable muscle contraction relieved by stretching favours cramp rather than a diffuse urge with unpleasant sensations.

Peripheral neuropathy

Persistent burning, numbness and sensory loss that does not reliably improve with movement supports neuropathy rather than RLS.

Akathisia

Whole-body inner restlessness after dopamine blockade lacks the characteristic evening sensory pattern and leg-focused relief described in RLS.

Vascular or musculoskeletal pain

Exertional calf pain, joint restriction or positional radicular symptoms follow mechanical or vascular patterns rather than rest–relief–evening criteria.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01DiagnoseTest the four-part symptom patternFirst stepNight-time leg discomfort, urge or insomnia is reported.

11. Ask whether symptoms begin at rest, are temporarily relieved by movement and show evening predominance, documenting exceptions and severity.
22. Compare cramps, neuropathy, venous disease, arthritis, positional discomfort and akathisia through sensory description, examination and medication timing.
33. Assess sleep loss, mood, work, pregnancy and kidney disease, and ask whether a relative has a similar pattern.
44. Request iron indices and relevant renal or metabolic tests before assigning primary disease or starting long-term symptomatic medication.

02First stepsCorrect causes and reduce triggersRLS is clinically likely and no urgent mimic has been identified.

11. Explain the disorder and use regular sleep timing, moderate daytime exercise, stretching, massage, warmth and reduction of late stimulants according to preference.
22. Treat biochemical iron deficiency with an agreed oral or specialist intravenous regimen and investigate blood loss, diet or malabsorption when indicated.
33. Review exacerbating medicines collaboratively, changing timing or agent only when the benefit–risk balance permits.
44. If symptoms remain frequent and disabling, select a medicine around renal function, pain, insomnia, pregnancy, falls and dependence risk.

03EscalateRecognise treatment-induced worseningEscalationSymptoms worsen or move earlier despite dopamine or other long-term therapy.

11. Establish whether the change is augmentation, tolerance, iron depletion, missed doses or a new mimic rather than automatically increasing treatment.
22. Repeat iron assessment and review dose timing, impulse-control symptoms, daytime sleepiness and all sedative medicines.
33. Discuss gradual dopaminergic reduction and substitution with a sleep or neurology specialist; abrupt withdrawal can cause severe rebound.
44. Refer refractory disease for specialist combination or opioid consideration with explicit respiratory, dependence and monitoring safeguards.

Key medicines and prescribing safety3 treatments · regimens, roles and cautions

Restores inadequate iron stores that can drive RLS and may reduce the need for long-term symptomatic medication.

Oral iron replacement

When biochemical deficiency is confirmed, a common regimen is ferrous sulfate 200 mg once daily or on alternate days, adjusted to elemental iron, tolerability and the local replacement protocol.

Confirm deficiency and investigate its cause. Explain gastrointestinal effects and interaction spacing, recheck indices after a defined interval and avoid continued iron when stores are adequate or overload is possible.

Can reduce sensory symptoms and improve sleep, particularly when RLS is frequent or accompanied by pain.

Pregabalin

A specialist or experienced prescriber may start 25–75 mg in the evening and titrate cautiously to symptom response, reducing dose in renal impairment under current BNF guidance.

It is a controlled drug with sedation, dizziness, oedema, weight gain, misuse and dependence potential. Avoid abrupt withdrawal, review respiratory depressants and discuss pregnancy and driving.

Can reduce intermittent or persistent RLS symptoms when non-drug measures, iron correction and preferred alternatives are insufficient or unsuitable.

Ropinirole

When a dopamine agonist is selected, a typical adult start is 0.25 mg once daily one to three hours before bedtime with slow protocol-based titration to the lowest effective dose.

Counsel before treatment about augmentation, nausea, hypotension, sudden sleep, hallucinations and impulse-control disorders. Review early-onset spread rather than responding automatically with a higher dose.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Insomnia and daytime impairment

Repeated need to move delays sleep, fragments rest and causes fatigue, poor concentration and driving risk.

Mood and quality-of-life loss

Chronic sleep disruption and discomfort contribute to anxiety, low mood, relationship strain and reduced work performance.

Dopaminergic augmentation

Long-term dopamine treatment can shift symptoms earlier, intensify them and spread them beyond the legs, creating a difficult treatment cycle.

Medicine-related harm

Sedating or dependence-forming medicines can cause falls, cognitive slowing, respiratory risk and withdrawal symptoms during treatment.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Track symptom onset time, rest latency, body distribution, nights affected and sleep or daytime function using a simple diary during treatment changes.
Repeat ferritin and transferrin saturation after iron therapy at the locally specified interval and stop or modify replacement when the agreed target is reached.
Check renal function, sedation, dizziness, oedema, falls, driving and misuse risk with gabapentin or pregabalin.
At every dopamine-agonist review, ask directly about augmentation, gambling, shopping, eating, hypersexuality, hallucinations and sleep attacks.
Reconsider neuropathy, sleep apnoea, kidney disease and medication triggers when an apparently adequate regimen fails.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Movement is diagnostic

Immediate but temporary relief while walking is not just coping behaviour; it is one of the defining features separating RLS from persistent neuropathic pain.

Anaemia is not required

Brain iron biology and depleted stores can be relevant before haemoglobin falls, so a normal full blood count does not complete the iron assessment.

Augmentation moves the clock

Dopaminergic treatment can shift symptoms from bedtime into afternoon, shorten the rest needed to provoke them and spread sensations to the arms.

Periodic movements differ

Repetitive limb movements during sleep are an associated physiological finding, while RLS is a waking sensory urge diagnosed from the clinical history.

Pregnancy is often temporary

New RLS commonly improves after delivery, but iron, sleep and medication decisions during pregnancy still need obstetric and primary-care coordination.

11Common pitfallsFrequent interpretation and management errors.

01
Calling every night-time leg symptom RLS misses nocturnal cramp, neuropathy, venous disease and akathisia with different treatments.
02
Prescribing iron from symptoms alone without indices risks overload while failing to investigate occult blood loss or malabsorption.
03
Escalating ropinirole when symptoms begin earlier and spread can intensify augmentation and make eventual withdrawal more difficult.
04
Using pregabalin without renal adjustment or a dependence discussion increases sedation, falls and respiratory risk.
05
Stopping a dopamine agonist abruptly after long exposure can cause severe rebound insomnia and restlessness requiring a supervised transition.