Clonazepam: uses, side effects and withdrawal

Clonazepam is a benzodiazepine that increases the calming chemical GABA in the brain. That is how it relieves anxiety, stops seizures and relaxes tense muscles. The NHS lists epileptic seizures, involuntary muscle spasms, panic disorder and, sometimes, restless legs syndrome.

Adults aged 18 and over can take the tablets and liquid, and children from 1 month old can be given it for epilepsy.

Tablets are swallowed with water and the liquid is measured with a syringe or spoon. It can be taken with or without food, in one dose or split across up to three a day.

The NHS gives examples. For epilepsy or muscle spasms in adults, start at 1 mg at night and increase to 4 to 8 mg over 2 to 4 weeks. For panic disorder, 1 to 2 mg daily. For restless legs, 0.5 to 2 mg daily. Lower doses are used for people over 65 or with kidney, liver or breathing problems. Your own dose is set by your prescriber.

If you miss a dose, take it unless the next dose is near. Never double up. If you take too much, call NHS 111; signs include poor coordination, sleepiness, irregular heartbeat, uncontrolled eye movements and muscle weakness.

Addiction risk is low if clonazepam is taken for 2 to 4 weeks or less, and higher if you have had alcohol or drug problems. After more than 4 weeks, the dose is reduced gradually. Stopping suddenly may cause confusion, seizures, depression, anxiety, sweating and diarrhoea. Do not stop without talking to a doctor.

Common effects affect more than 1 in 100 people.

• Disturbed sleep or vivid dreams: speak to a doctor, who may lower the dose.

• Daytime drowsiness: improves after about a week; avoid driving and machinery.

• Dizziness or light-headedness: rise slowly and avoid driving until it passes.

• Muscle weakness: sit down if weak and seek advice if it lasts beyond a week.

• Call NHS 111 for yellowing eyes or skin, hallucinations, coordination problems, easy bruising or nosebleeds, mood changes or memory problems. Call 999 for breathing difficulty or anaphylaxis.

Tell the prescriber about allergic reactions, myasthenia gravis, sleep apnoea, lung, liver or kidney problems, spinal or cerebellar ataxia, past alcohol or drug problems, recent bereavement or depression, suicidal thoughts, a personality disorder, pregnancy or breastfeeding, and planned anaesthesia.

Alcohol increases the risk of dangerous deep sleep and breathing problems. Cannabis, heroin, methadone, cocaine and stimulants can increase drowsiness. The NHS lists anticonvulsants, antipsychotics, antidepressants, hypnotics, muscle relaxants such as baclofen and tizanidine, several blood pressure medicines, sedating antihistamines, strong painkillers, cimetidine, rifampicin and fluconazole. Valerian and passionflower can add to drowsiness.

It can be taken in pregnancy, particularly for epilepsy control, but take advice before conception. Late use may make the baby drowsy and newborns are monitored. It passes into breast milk in very small amounts; avoid bed-sharing.

For panic disorder, the NHS mentions SSRIs and talking therapies such as CBT. For epilepsy there are other anti-epileptic medicines. Suspected side effects can be reported to the MHRA Yellow Card scheme.