Muscle twitching all over the body: causes, red flags and when to get it checked

A fasciculation is a brief, visible flicker of a small group of muscle fibres. Anyone can experience them, and surveys find they are present in a large proportion of healthy people at some time. They usually reflect irritability of the nerve endings rather than disease of the nerve.

• Benign fasciculation: twitching in calves, thighs, arms or eyelids that comes and goes, without weakness.

• Caffeine, nicotine, energy drinks and stimulant medicines, including some ADHD and asthma drugs.

• Stress, anxiety and sleep deprivation, which often cause heightened body awareness and twitching.

• After strenuous exercise, or dehydration and low magnesium, potassium or calcium.

• Medicines such as salbutamol, steroids, diuretics and some antidepressants.

• Overactive thyroid, which can cause tremor and twitching alongside weight loss and palpitations.

• Nerve root irritation or neuropathy, with local twitching and numbness.

• Motor neurone disease and other motor nerve disorders, which are rare and almost always show progressive weakness and wasting alongside.

Progressive weakness, difficulty gripping or climbing stairs, visible muscle thinning, a foot that drags, slurred speech, swallowing difficulty, cramps with stiffness or fasciculations that are persistent and confined to one limb deserve specialist review.

• Call 999: sudden weakness, difficulty breathing or swallowing, or facial droop.

• GP within days: twitching with new weakness, dropping things, tripping or slurred speech.

• GP within weeks: twitching lasting more than a few weeks with muscle thinning or cramps.

• Routine GP: widespread twitching with no weakness, that you would like reassurance about.

Doctors ask about the distribution and duration, triggers, caffeine, medicines, sleep, stress, any weakness or change in function, family history and weight change. They examine muscle bulk, tone, power and reflexes in the arms and legs, tongue appearance and speech, and look for thyroid signs.

• Blood tests: thyroid function, electrolytes (calcium, magnesium, potassium), kidney function, glucose and creatine kinase.

• EMG and nerve conduction studies: show whether the twitching comes from irritable but healthy nerves or from nerve damage.

• MRI of spine or brain: only if examination suggests a structural cause.

• Review of medicines and substances.

Cut back caffeine and stimulants, protect sleep, manage stress with exercise, relaxation or talking therapy, and keep hydrated. Avoid frequent checking and internet searching for symptoms, which can fuel anxiety and heighten awareness of twitches. Regular stretching helps related cramps.

The NHS route is a GP, with neurology referral if weakness or wasting is found. Private neurology consultation with EMG offers a faster route to reassurance.