Nocturnal leg cramps — sudden, painful, involuntary contractions of the calf, foot or thigh muscles during sleep or rest — are one of the most common complaints pharmacists hear from older patients. According to NICE Clinical Knowledge Summaries, approximately one in three adults over 60 experience nocturnal leg cramps, with prevalence increasing further with age. The condition disrupts sleep, affects quality of life and frequently prompts pharmacy visits.

What Causes Nocturnal Leg Cramps?

In most cases, the precise cause is unknown (idiopathic). However, several contributing factors are recognised:

Medication-related cramps

Pharmacists should be alert to medications that can cause or worsen leg cramps:

• Diuretics (furosemide, bendroflumethiazide) — electrolyte depletion, particularly potassium and magnesium
• Statins — muscle-related side effects are well documented
• Long-acting beta-2 agonists (salmeterol) — potassium shift
• ACE inhibitors — electrolyte effects
• Oral contraceptives — circulatory changes
• Nifedipine — paradoxically, despite being used to treat cramps in some countries

If a patient's cramps began or worsened after starting a new medication, this is worth flagging in a conversation with their prescriber.

Pharmacy Management

Stretching exercises — first-line advice

NICE CKS recommends regular calf stretching as the primary non-pharmacological intervention, and it is the most evidence-supported approach.

Calf stretch technique:

1. Stand an arm's length from a wall, feet hip-width apart
2. Step one foot back, keeping the back leg straight and the heel on the floor
3. Bend the front knee until a stretch is felt in the back calf
4. Hold for 30 seconds, repeat three times each side
5. Perform three times daily, including immediately before bed

During an acute cramp:

• Straighten the leg and pull the toes firmly towards the shin (dorsiflexion)
• Massage the cramping muscle
• Walk around — weight-bearing stretches the calf
• Apply a warm towel or hot water bottle to the muscle after the cramp resolves

Hydration

Advise patients to ensure adequate fluid intake, particularly in the evening. Dehydration is a modifiable risk factor that is often overlooked in elderly patients who may deliberately restrict fluid intake to avoid nocturnal trips to the toilet. A glass of water before bed is a reasonable compromise.

Magnesium supplements

Magnesium supplementation is widely used for nocturnal leg cramps, although the evidence base is mixed. A Cochrane review found no significant benefit for idiopathic cramps in older adults, but some benefit for pregnancy-related cramps.

Despite the limited trial evidence, magnesium remains popular with patients and is widely recommended by pharmacists. Magnesium citrate or magnesium glycinate are better absorbed than magnesium oxide. A typical dose is 200–400mg daily, taken in the evening.

Pharmacists should advise patients that:

• Magnesium may take 4–6 weeks to show benefit
• High doses can cause diarrhoea — start at the lower end
• Patients with renal impairment should consult their GP before supplementing, as magnesium clearance depends on kidney function

Quinine — prescription only and restricted

Quinine sulfate was historically the standard treatment for nocturnal leg cramps, but its use has been significantly restricted due to serious adverse effects including thrombocytopenia, cardiac arrhythmias and cinchonism. NICE CKS advises that quinine should only be considered when cramps are very frequent and distressing, other treatable causes have been excluded, and non-pharmacological measures have failed.

Quinine is prescription-only. Pharmacists should not recommend tonic water as a self-treatment — the quinine content is too low to be therapeutic and encourages patients to bypass medical review.

Tonic water — does it work?

Patients frequently ask about tonic water for cramps. Standard tonic water contains approximately 83mg/L of quinine — a therapeutic dose for cramps would be 200–300mg. A patient would need to drink 2.5–3.5 litres of tonic water daily to reach a therapeutic dose, consuming substantial sugar and calories in the process. Pharmacists should advise that tonic water is not an effective treatment and that patients with frequent, disruptive cramps should discuss quinine prescribing with their GP.

When to Refer

Most nocturnal leg cramps are benign, but pharmacists should refer to a GP if:

• Cramps are associated with leg swelling, redness or warmth — potential deep vein thrombosis
• The patient has persistent muscle weakness alongside cramps — possible neuromuscular condition
• Cramps are accompanied by numbness, tingling or skin colour changes — peripheral vascular disease or neuropathy
• The cramps began after starting a new medication
• The patient has known kidney disease — electrolyte management may be needed
• Cramps are daily and severely disrupting sleep despite stretching and hydration
• There is muscle wasting or fasciculation — consider motor neuron disease referral, particularly in patients over 50

Pregnancy-Related Cramps

Leg cramps affect up to 50% of pregnant women, predominantly in the third trimester. Management is more restricted in pregnancy:

• Stretching exercises remain first-line
• Magnesium supplementation has some evidence of benefit in pregnancy and is generally considered safe
• Quinine is contraindicated in pregnancy
• NSAIDs should be avoided, particularly from 30 weeks
• Paracetamol can be used for post-cramp muscle soreness

The Pharmacy Opportunity

Nocturnal leg cramps are a condition where pharmacy advice adds genuine value. The condition is common, the interventions are accessible (stretching, hydration, magnesium), and the pharmacist can identify medication-related causes and flag them for prescriber review. For patients who have silently tolerated cramps for years, a proactive conversation can significantly improve their sleep and quality of life.

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